[v5,6/9] gfxstream + rutabaga: add initial support for gfxstream

Commit Message

Gurchetan Singh Aug. 15, 2023, 12:35 a.m. UTC

This adds initial support for gfxstream and cross-domain.  Both
features rely on virtio-gpu blob resources and context types, which
are also implemented in this patch.

gfxstream has a long and illustrious history in Android graphics
paravirtualization.  It has been powering graphics in the Android
Studio Emulator for more than a decade, which is the main developer
platform.

Originally conceived by Jesse Hall, it was first known as "EmuGL" [a].
The key design characteristic was a 1:1 threading model and
auto-generation, which fit nicely with the OpenGLES spec.  It also
allowed easy layering with ANGLE on the host, which provides the GLES
implementations on Windows or MacOS enviroments.

gfxstream has traditionally been maintained by a single engineer, and
between 2015 to 2021, the goldfish throne passed to Frank Yang.
Historians often remark this glorious reign ("pax gfxstreama" is the
academic term) was comparable to that of Augustus and both Queen
Elizabeths.  Just to name a few accomplishments in a resplendent
panoply: higher versions of GLES, address space graphics, snapshot
support and CTS compliant Vulkan [b].

One major drawback was the use of out-of-tree goldfish drivers.
Android engineers didn't know much about DRM/KMS and especially TTM so
a simple guest to host pipe was conceived.

Luckily, virtio-gpu 3D started to emerge in 2016 due to the work of
the Mesa/virglrenderer communities.  In 2018, the initial virtio-gpu
port of gfxstream was done by Cuttlefish enthusiast Alistair Delva.
It was a symbol compatible replacement of virglrenderer [c] and named
"AVDVirglrenderer".  This implementation forms the basis of the
current gfxstream host implementation still in use today.

cross-domain support follows a similar arc.  Originally conceived by
Wayland aficionado David Reveman and crosvm enjoyer Zach Reizner in
2018, it initially relied on the downstream "virtio-wl" device.

In 2020 and 2021, virtio-gpu was extended to include blob resources
and multiple timelines by yours truly, features gfxstream/cross-domain
both require to function correctly.

Right now, we stand at the precipice of a truly fantastic possibility:
the Android Emulator powered by upstream QEMU and upstream Linux
kernel.  gfxstream will then be packaged properfully, and app
developers can even fix gfxstream bugs on their own if they encounter
them.

It's been quite the ride, my friends.  Where will gfxstream head next,
nobody really knows.  I wouldn't be surprised if it's around for
another decade, maintained by a new generation of Android graphics
enthusiasts.

Technical details:
  - Very simple initial display integration: just used Pixman
  - Largely, 1:1 mapping of virtio-gpu hypercalls to rutabaga function
    calls

Next steps for Android VMs:
  - The next step would be improving display integration and UI interfaces
    with the goal of the QEMU upstream graphics being in an emulator
    release [d].

Next steps for Linux VMs for display virtualization:
  - For widespread distribution, someone needs to package Sommelier or the
    wayland-proxy-virtwl [e] ideally into Debian main. In addition, newer
    versions of the Linux kernel come with DRM_VIRTIO_GPU_KMS option,
    which allows disabling KMS hypercalls.  If anyone cares enough, it'll
    probably be possible to build a custom VM variant that uses this display
    virtualization strategy.

[a] https://android-review.googlesource.com/c/platform/development/+/34470
[b] https://android-review.googlesource.com/q/topic:%22vulkan-hostconnection-start%22
[c] https://android-review.googlesource.com/c/device/generic/goldfish-opengl/+/761927
[d] https://developer.android.com/studio/releases/emulator
[e] https://github.com/talex5/wayland-proxy-virtwl

Signed-off-by: Gurchetan Singh <[e-mail]>
Tested-by: Alyssa Ross <[e-mail]>
---
v1: Incorported various suggestions by Akihiko Odaki and Bernard Berschow
    - Removed GET_VIRTIO_GPU_GL / GET_RUTABAGA macros
    - Used error_report(..)
    - Used g_autofree to fix leaks on error paths
    - Removed unnecessary casts
    - added virtio-gpu-pci-rutabaga.c + virtio-vga-rutabaga.c files

v2: Incorported various suggestions by Akihiko Odaki, Marc-André Lureau and
    Bernard Berschow:
    - Parenthesis in CHECK macro
    - CHECK_RESULT(result, ..) --> CHECK(!result, ..)
    - delay until g->parent_obj.enable = 1
    - Additional cast fixes
    - initialize directly in virtio_gpu_rutabaga_realize(..)
    - add debug callback to hook into QEMU error's APIs

v3: Incorporated feedback from Akihiko Odaki and Alyssa Ross:
    - Autodetect Wayland socket when not explicitly specified
    - Fix map_blob error paths
    - Add comment why we need both `res` and `resource` in create blob
    - Cast and whitespace fixes
    - Big endian check comes before virtio_gpu_rutabaga_init().
    - VirtIOVGARUTABAGA --> VirtIOVGARutabaga

v4: Incorporated feedback from Akihiko Odaki and Alyssa Ross:
    - Double checked all casts
    - Remove unnecessary parenthesis
    - Removed `resource` in create_blob
    - Added comment about failure case
    - Pass user-provided socket as-is
    - Use stack variable rather than heap allocation
    - Future-proofed map info API to give access flags as well

v5: Incorporated feedback from Akihiko Odaki:
    - Check (ss.scanout_id < VIRTIO_GPU_MAX_SCANOUTS)
    - Simplify num_capsets check
    - Call cleanup mapping on error paths
    - uint64_t --> void* for rutabaga_map(..)
    - Removed unnecessary parenthesis
    - Removed unnecessary cast
    - #define UNIX_PATH_MAX sizeof((struct sockaddr_un) {}.sun_path)
    - Reuse result variable
    - Report error when default socket doesn't fit in Wayland socket path

 hw/display/virtio-gpu-pci-rutabaga.c |   48 ++
 hw/display/virtio-gpu-rutabaga.c     | 1114 ++++++++++++++++++++++++++
 hw/display/virtio-vga-rutabaga.c     |   51 ++
 3 files changed, 1213 insertions(+)
 create mode 100644 hw/display/virtio-gpu-pci-rutabaga.c
 create mode 100644 hw/display/virtio-gpu-rutabaga.c
 create mode 100644 hw/display/virtio-vga-rutabaga.c

Comments

Manos Pitsidianakis Aug. 15, 2023, 2:40 p.m. UTC | #1

Reviewed-by: Emmanouil Pitsidianakis <[e-mail]>
Tested-by: Emmanouil Pitsidianakis <[e-mail]>

On Tue, 15 Aug 2023 03:35, Gurchetan Singh <[e-mail]> wrote:
>This adds initial support for gfxstream and cross-domain.  Both
>features rely on virtio-gpu blob resources and context types, which
>are also implemented in this patch.
>
>gfxstream has a long and illustrious history in Android graphics
>paravirtualization.  It has been powering graphics in the Android
>Studio Emulator for more than a decade, which is the main developer
>platform.
>
>Originally conceived by Jesse Hall, it was first known as "EmuGL" [a].
>The key design characteristic was a 1:1 threading model and
>auto-generation, which fit nicely with the OpenGLES spec.  It also
>allowed easy layering with ANGLE on the host, which provides the GLES
>implementations on Windows or MacOS enviroments.
>
>gfxstream has traditionally been maintained by a single engineer, and
>between 2015 to 2021, the goldfish throne passed to Frank Yang.
>Historians often remark this glorious reign ("pax gfxstreama" is the
>academic term) was comparable to that of Augustus and both Queen
>Elizabeths.  Just to name a few accomplishments in a resplendent
>panoply: higher versions of GLES, address space graphics, snapshot
>support and CTS compliant Vulkan [b].
>
>One major drawback was the use of out-of-tree goldfish drivers.
>Android engineers didn't know much about DRM/KMS and especially TTM so
>a simple guest to host pipe was conceived.
>
>Luckily, virtio-gpu 3D started to emerge in 2016 due to the work of
>the Mesa/virglrenderer communities.  In 2018, the initial virtio-gpu
>port of gfxstream was done by Cuttlefish enthusiast Alistair Delva.
>It was a symbol compatible replacement of virglrenderer [c] and named
>"AVDVirglrenderer".  This implementation forms the basis of the
>current gfxstream host implementation still in use today.
>
>cross-domain support follows a similar arc.  Originally conceived by
>Wayland aficionado David Reveman and crosvm enjoyer Zach Reizner in
>2018, it initially relied on the downstream "virtio-wl" device.
>
>In 2020 and 2021, virtio-gpu was extended to include blob resources
>and multiple timelines by yours truly, features gfxstream/cross-domain
>both require to function correctly.
>
>Right now, we stand at the precipice of a truly fantastic possibility:
>the Android Emulator powered by upstream QEMU and upstream Linux
>kernel.  gfxstream will then be packaged properfully, and app
>developers can even fix gfxstream bugs on their own if they encounter
>them.
>
>It's been quite the ride, my friends.  Where will gfxstream head next,
>nobody really knows.  I wouldn't be surprised if it's around for
>another decade, maintained by a new generation of Android graphics
>enthusiasts.
>
>Technical details:
>  - Very simple initial display integration: just used Pixman
>  - Largely, 1:1 mapping of virtio-gpu hypercalls to rutabaga function
>    calls
>
>Next steps for Android VMs:
>  - The next step would be improving display integration and UI interfaces
>    with the goal of the QEMU upstream graphics being in an emulator
>    release [d].
>
>Next steps for Linux VMs for display virtualization:
>  - For widespread distribution, someone needs to package Sommelier or the
>    wayland-proxy-virtwl [e] ideally into Debian main. In addition, newer
>    versions of the Linux kernel come with DRM_VIRTIO_GPU_KMS option,
>    which allows disabling KMS hypercalls.  If anyone cares enough, it'll
>    probably be possible to build a custom VM variant that uses this display
>    virtualization strategy.
>
>[a] https://android-review.googlesource.com/c/platform/development/+/34470
>[b] https://android-review.googlesource.com/q/topic:%22vulkan-hostconnection-start%22
>[c] https://android-review.googlesource.com/c/device/generic/goldfish-opengl/+/761927
>[d] https://developer.android.com/studio/releases/emulator
>[e] https://github.com/talex5/wayland-proxy-virtwl
>
>Signed-off-by: Gurchetan Singh <[e-mail]>
>Tested-by: Alyssa Ross <[e-mail]>
>---
>v1: Incorported various suggestions by Akihiko Odaki and Bernard Berschow
>    - Removed GET_VIRTIO_GPU_GL / GET_RUTABAGA macros
>    - Used error_report(..)
>    - Used g_autofree to fix leaks on error paths
>    - Removed unnecessary casts
>    - added virtio-gpu-pci-rutabaga.c + virtio-vga-rutabaga.c files
>
>v2: Incorported various suggestions by Akihiko Odaki, Marc-André Lureau and
>    Bernard Berschow:
>    - Parenthesis in CHECK macro
>    - CHECK_RESULT(result, ..) --> CHECK(!result, ..)
>    - delay until g->parent_obj.enable = 1
>    - Additional cast fixes
>    - initialize directly in virtio_gpu_rutabaga_realize(..)
>    - add debug callback to hook into QEMU error's APIs
>
>v3: Incorporated feedback from Akihiko Odaki and Alyssa Ross:
>    - Autodetect Wayland socket when not explicitly specified
>    - Fix map_blob error paths
>    - Add comment why we need both `res` and `resource` in create blob
>    - Cast and whitespace fixes
>    - Big endian check comes before virtio_gpu_rutabaga_init().
>    - VirtIOVGARUTABAGA --> VirtIOVGARutabaga
>
>v4: Incorporated feedback from Akihiko Odaki and Alyssa Ross:
>    - Double checked all casts
>    - Remove unnecessary parenthesis
>    - Removed `resource` in create_blob
>    - Added comment about failure case
>    - Pass user-provided socket as-is
>    - Use stack variable rather than heap allocation
>    - Future-proofed map info API to give access flags as well
>
>v5: Incorporated feedback from Akihiko Odaki:
>    - Check (ss.scanout_id < VIRTIO_GPU_MAX_SCANOUTS)
>    - Simplify num_capsets check
>    - Call cleanup mapping on error paths
>    - uint64_t --> void* for rutabaga_map(..)
>    - Removed unnecessary parenthesis
>    - Removed unnecessary cast
>    - #define UNIX_PATH_MAX sizeof((struct sockaddr_un) {}.sun_path)
>    - Reuse result variable
>    - Report error when default socket doesn't fit in Wayland socket path
>
> hw/display/virtio-gpu-pci-rutabaga.c |   48 ++
> hw/display/virtio-gpu-rutabaga.c     | 1114 ++++++++++++++++++++++++++
> hw/display/virtio-vga-rutabaga.c     |   51 ++
> 3 files changed, 1213 insertions(+)
> create mode 100644 hw/display/virtio-gpu-pci-rutabaga.c
> create mode 100644 hw/display/virtio-gpu-rutabaga.c
> create mode 100644 hw/display/virtio-vga-rutabaga.c
>
>diff --git a/hw/display/virtio-gpu-pci-rutabaga.c b/hw/display/virtio-gpu-pci-rutabaga.c
>new file mode 100644
>index 0000000000..c71173d8ca
>--- /dev/null
>+++ b/hw/display/virtio-gpu-pci-rutabaga.c
>@@ -0,0 +1,48 @@
>+// SPDX-License-Identifier: GPL-2.0
>+
>+#include "qemu/osdep.h"
>+#include "qapi/error.h"
>+#include "qemu/module.h"
>+#include "hw/pci/pci.h"
>+#include "hw/qdev-properties.h"
>+#include "hw/virtio/virtio.h"
>+#include "hw/virtio/virtio-bus.h"
>+#include "hw/virtio/virtio-gpu-pci.h"
>+#include "qom/object.h"
>+
>+#define TYPE_VIRTIO_GPU_RUTABAGA_PCI "virtio-gpu-rutabaga-pci"
>+typedef struct VirtIOGPURutabagaPCI VirtIOGPURutabagaPCI;
>+DECLARE_INSTANCE_CHECKER(VirtIOGPURutabagaPCI, VIRTIO_GPU_RUTABAGA_PCI,
>+                         TYPE_VIRTIO_GPU_RUTABAGA_PCI)
>+
>+struct VirtIOGPURutabagaPCI {
>+    VirtIOGPUPCIBase parent_obj;
>+    VirtIOGPURutabaga vdev;
>+};
>+
>+static void virtio_gpu_rutabaga_initfn(Object *obj)
>+{
>+    VirtIOGPURutabagaPCI *dev = VIRTIO_GPU_RUTABAGA_PCI(obj);
>+
>+    virtio_instance_init_common(obj, &dev->vdev, sizeof(dev->vdev),
>+                                TYPE_VIRTIO_GPU_RUTABAGA);
>+    VIRTIO_GPU_PCI_BASE(obj)->vgpu = VIRTIO_GPU_BASE(&dev->vdev);
>+}
>+
>+static const VirtioPCIDeviceTypeInfo virtio_gpu_rutabaga_pci_info = {
>+    .generic_name = TYPE_VIRTIO_GPU_RUTABAGA_PCI,
>+    .parent = TYPE_VIRTIO_GPU_PCI_BASE,
>+    .instance_size = sizeof(VirtIOGPURutabagaPCI),
>+    .instance_init = virtio_gpu_rutabaga_initfn,
>+};
>+module_obj(TYPE_VIRTIO_GPU_RUTABAGA_PCI);
>+module_kconfig(VIRTIO_PCI);
>+
>+static void virtio_gpu_rutabaga_pci_register_types(void)
>+{
>+    virtio_pci_types_register(&virtio_gpu_rutabaga_pci_info);
>+}
>+
>+type_init(virtio_gpu_rutabaga_pci_register_types)
>+
>+module_dep("hw-display-virtio-gpu-pci");
>diff --git a/hw/display/virtio-gpu-rutabaga.c b/hw/display/virtio-gpu-rutabaga.c
>new file mode 100644
>index 0000000000..3f9f106abc
>--- /dev/null
>+++ b/hw/display/virtio-gpu-rutabaga.c
>@@ -0,0 +1,1114 @@
>+// SPDX-License-Identifier: GPL-2.0
>+
>+#include "qemu/osdep.h"
>+#include "qapi/error.h"
>+#include "qemu/error-report.h"
>+#include "qemu/iov.h"
>+#include "trace.h"
>+#include "hw/virtio/virtio.h"
>+#include "hw/virtio/virtio-gpu.h"
>+#include "hw/virtio/virtio-gpu-pixman.h"
>+#include "hw/virtio/virtio-iommu.h"
>+
>+#include <glib/gmem.h>
>+#include <rutabaga_gfx/rutabaga_gfx_ffi.h>
>+
>+#define CHECK(condition, cmd)                                                 \
>+    do {                                                                      \
>+        if (!(condition)) {                                                   \
>+            error_report("CHECK failed in %s() %s:" "%d", __func__,           \
>+                         __FILE__, __LINE__);                                 \
>+            (cmd)->error = VIRTIO_GPU_RESP_ERR_UNSPEC;                        \
>+            return;                                                           \
>+       }                                                                      \
>+    } while (0)
>+
>+/*
>+ * This is the size of the char array in struct sock_addr_un. No Wayland socket
>+ * can be created with a path longer than this, including the null terminator.
>+ */
>+#ifndef UNIX_PATH_MAX
>+#define UNIX_PATH_MAX sizeof((struct sockaddr_un) {} .sun_path)
>+#endif
>+
>+struct rutabaga_aio_data {
>+    struct VirtIOGPURutabaga *vr;
>+    struct rutabaga_fence fence;
>+};
>+
>+static void
>+virtio_gpu_rutabaga_update_cursor(VirtIOGPU *g, struct virtio_gpu_scanout *s,
>+                                  uint32_t resource_id)
>+{
>+    struct virtio_gpu_simple_resource *res;
>+    struct rutabaga_transfer transfer = { 0 };
>+    struct iovec transfer_iovec;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    res = virtio_gpu_find_resource(g, resource_id);
>+    if (!res) {
>+        return;
>+    }
>+
>+    if (res->width != s->current_cursor->width ||
>+        res->height != s->current_cursor->height) {
>+        return;
>+    }
>+
>+    transfer.x = 0;
>+    transfer.y = 0;
>+    transfer.z = 0;
>+    transfer.w = res->width;
>+    transfer.h = res->height;
>+    transfer.d = 1;
>+
>+    transfer_iovec.iov_base = s->current_cursor->data;
>+    transfer_iovec.iov_len = res->width * res->height * 4;
>+
>+    rutabaga_resource_transfer_read(vr->rutabaga, 0,
>+                                    resource_id, &transfer,
>+                                    &transfer_iovec);
>+}
>+
>+static void
>+virtio_gpu_rutabaga_gl_flushed(VirtIOGPUBase *b)
>+{
>+    VirtIOGPU *g = VIRTIO_GPU(b);
>+    virtio_gpu_process_cmdq(g);
>+}
>+
>+static void
>+rutabaga_cmd_create_resource_2d(VirtIOGPU *g,
>+                                struct virtio_gpu_ctrl_command *cmd)
>+{
>+    int32_t result;
>+    struct rutabaga_create_3d rc_3d = { 0 };
>+    struct virtio_gpu_simple_resource *res;
>+    struct virtio_gpu_resource_create_2d c2d;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    VIRTIO_GPU_FILL_CMD(c2d);
>+    trace_virtio_gpu_cmd_res_create_2d(c2d.resource_id, c2d.format,
>+                                       c2d.width, c2d.height);
>+
>+    rc_3d.target = 2;
>+    rc_3d.format = c2d.format;
>+    rc_3d.bind = (1 << 1);
>+    rc_3d.width = c2d.width;
>+    rc_3d.height = c2d.height;
>+    rc_3d.depth = 1;
>+    rc_3d.array_size = 1;
>+    rc_3d.last_level = 0;
>+    rc_3d.nr_samples = 0;
>+    rc_3d.flags = VIRTIO_GPU_RESOURCE_FLAG_Y_0_TOP;
>+
>+    result = rutabaga_resource_create_3d(vr->rutabaga, c2d.resource_id, &rc_3d);
>+    CHECK(!result, cmd);
>+
>+    res = g_new0(struct virtio_gpu_simple_resource, 1);
>+    res->width = c2d.width;
>+    res->height = c2d.height;
>+    res->format = c2d.format;
>+    res->resource_id = c2d.resource_id;
>+
>+    QTAILQ_INSERT_HEAD(&g->reslist, res, next);
>+}
>+
>+static void
>+rutabaga_cmd_create_resource_3d(VirtIOGPU *g,
>+                                struct virtio_gpu_ctrl_command *cmd)
>+{
>+    int32_t result;
>+    struct rutabaga_create_3d rc_3d = { 0 };
>+    struct virtio_gpu_simple_resource *res;
>+    struct virtio_gpu_resource_create_3d c3d;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    VIRTIO_GPU_FILL_CMD(c3d);
>+
>+    trace_virtio_gpu_cmd_res_create_3d(c3d.resource_id, c3d.format,
>+                                       c3d.width, c3d.height, c3d.depth);
>+
>+    rc_3d.target = c3d.target;
>+    rc_3d.format = c3d.format;
>+    rc_3d.bind = c3d.bind;
>+    rc_3d.width = c3d.width;
>+    rc_3d.height = c3d.height;
>+    rc_3d.depth = c3d.depth;
>+    rc_3d.array_size = c3d.array_size;
>+    rc_3d.last_level = c3d.last_level;
>+    rc_3d.nr_samples = c3d.nr_samples;
>+    rc_3d.flags = c3d.flags;
>+
>+    result = rutabaga_resource_create_3d(vr->rutabaga, c3d.resource_id, &rc_3d);
>+    CHECK(!result, cmd);
>+
>+    res = g_new0(struct virtio_gpu_simple_resource, 1);
>+    res->width = c3d.width;
>+    res->height = c3d.height;
>+    res->format = c3d.format;
>+    res->resource_id = c3d.resource_id;
>+
>+    QTAILQ_INSERT_HEAD(&g->reslist, res, next);
>+}
>+
>+static void
>+rutabaga_cmd_resource_unref(VirtIOGPU *g,
>+                            struct virtio_gpu_ctrl_command *cmd)
>+{
>+    int32_t result;
>+    struct virtio_gpu_simple_resource *res;
>+    struct virtio_gpu_resource_unref unref;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    VIRTIO_GPU_FILL_CMD(unref);
>+
>+    trace_virtio_gpu_cmd_res_unref(unref.resource_id);
>+
>+    res = virtio_gpu_find_resource(g, unref.resource_id);
>+    CHECK(res, cmd);
>+
>+    result = rutabaga_resource_unref(vr->rutabaga, unref.resource_id);
>+    CHECK(!result, cmd);
>+
>+    if (res->image) {
>+        pixman_image_unref(res->image);
>+    }
>+
>+    QTAILQ_REMOVE(&g->reslist, res, next);
>+    g_free(res);
>+}
>+
>+static void
>+rutabaga_cmd_context_create(VirtIOGPU *g,
>+                            struct virtio_gpu_ctrl_command *cmd)
>+{
>+    int32_t result;
>+    struct virtio_gpu_ctx_create cc;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    VIRTIO_GPU_FILL_CMD(cc);
>+    trace_virtio_gpu_cmd_ctx_create(cc.hdr.ctx_id,
>+                                    cc.debug_name);
>+
>+    result = rutabaga_context_create(vr->rutabaga, cc.hdr.ctx_id,
>+                                     cc.context_init, cc.debug_name, cc.nlen);
>+    CHECK(!result, cmd);
>+}
>+
>+static void
>+rutabaga_cmd_context_destroy(VirtIOGPU *g,
>+                             struct virtio_gpu_ctrl_command *cmd)
>+{
>+    int32_t result;
>+    struct virtio_gpu_ctx_destroy cd;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    VIRTIO_GPU_FILL_CMD(cd);
>+    trace_virtio_gpu_cmd_ctx_destroy(cd.hdr.ctx_id);
>+
>+    result = rutabaga_context_destroy(vr->rutabaga, cd.hdr.ctx_id);
>+    CHECK(!result, cmd);
>+}
>+
>+static void
>+rutabaga_cmd_resource_flush(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd)
>+{
>+    int32_t result, i;
>+    struct virtio_gpu_scanout *scanout = NULL;
>+    struct virtio_gpu_simple_resource *res;
>+    struct rutabaga_transfer transfer = { 0 };
>+    struct iovec transfer_iovec;
>+    struct virtio_gpu_resource_flush rf;
>+    bool found = false;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+    if (vr->headless) {
>+        return;
>+    }
>+
>+    VIRTIO_GPU_FILL_CMD(rf);
>+    trace_virtio_gpu_cmd_res_flush(rf.resource_id,
>+                                   rf.r.width, rf.r.height, rf.r.x, rf.r.y);
>+
>+    res = virtio_gpu_find_resource(g, rf.resource_id);
>+    CHECK(res, cmd);
>+
>+    for (i = 0; i < g->parent_obj.conf.max_outputs; i++) {
>+        scanout = &g->parent_obj.scanout[i];
>+        if (i == res->scanout_bitmask) {
>+            found = true;
>+            break;
>+        }
>+    }
>+
>+    if (!found) {
>+        return;
>+    }
>+
>+    transfer.x = 0;
>+    transfer.y = 0;
>+    transfer.z = 0;
>+    transfer.w = res->width;
>+    transfer.h = res->height;
>+    transfer.d = 1;
>+
>+    transfer_iovec.iov_base = pixman_image_get_data(res->image);
>+    transfer_iovec.iov_len = res->width * res->height * 4;
>+
>+    result = rutabaga_resource_transfer_read(vr->rutabaga, 0,
>+                                             rf.resource_id, &transfer,
>+                                             &transfer_iovec);
>+    CHECK(!result, cmd);
>+    dpy_gfx_update_full(scanout->con);
>+}
>+
>+static void
>+rutabaga_cmd_set_scanout(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd)
>+{
>+    struct virtio_gpu_simple_resource *res;
>+    struct virtio_gpu_scanout *scanout = NULL;
>+    struct virtio_gpu_set_scanout ss;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+    if (vr->headless) {
>+        return;
>+    }
>+
>+    VIRTIO_GPU_FILL_CMD(ss);
>+    trace_virtio_gpu_cmd_set_scanout(ss.scanout_id, ss.resource_id,
>+                                     ss.r.width, ss.r.height, ss.r.x, ss.r.y);
>+
>+    CHECK(ss.scanout_id < VIRTIO_GPU_MAX_SCANOUTS, cmd);
>+    scanout = &g->parent_obj.scanout[ss.scanout_id];
>+
>+    if (ss.resource_id == 0) {
>+        return;
>+    }
>+
>+    res = virtio_gpu_find_resource(g, ss.resource_id);
>+    CHECK(res, cmd);
>+
>+    if (!res->image) {
>+        pixman_format_code_t pformat;
>+        pformat = virtio_gpu_get_pixman_format(res->format);
>+        CHECK(pformat, cmd);
>+
>+        res->image = pixman_image_create_bits(pformat,
>+                                              res->width,
>+                                              res->height,
>+                                              NULL, 0);
>+        CHECK(res->image, cmd);
>+        pixman_image_ref(res->image);
>+    }
>+
>+    g->parent_obj.enable = 1;
>+
>+    /* realloc the surface ptr */
>+    scanout->ds = qemu_create_displaysurface_pixman(res->image);
>+    dpy_gfx_replace_surface(scanout->con, NULL);
>+    dpy_gfx_replace_surface(scanout->con, scanout->ds);
>+    res->scanout_bitmask = ss.scanout_id;
>+}
>+
>+static void
>+rutabaga_cmd_submit_3d(VirtIOGPU *g,
>+                       struct virtio_gpu_ctrl_command *cmd)
>+{
>+    int32_t result;
>+    struct virtio_gpu_cmd_submit cs;
>+    struct rutabaga_command rutabaga_cmd = { 0 };
>+    g_autofree uint8_t *buf = NULL;
>+    size_t s;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    VIRTIO_GPU_FILL_CMD(cs);
>+    trace_virtio_gpu_cmd_ctx_submit(cs.hdr.ctx_id, cs.size);
>+
>+    buf = g_new0(uint8_t, cs.size);
>+    s = iov_to_buf(cmd->elem.out_sg, cmd->elem.out_num,
>+                   sizeof(cs), buf, cs.size);
>+    CHECK(s == cs.size, cmd);
>+
>+    rutabaga_cmd.ctx_id = cs.hdr.ctx_id;
>+    rutabaga_cmd.cmd = buf;
>+    rutabaga_cmd.cmd_size = cs.size;
>+
>+    result = rutabaga_submit_command(vr->rutabaga, &rutabaga_cmd);
>+    CHECK(!result, cmd);
>+}
>+
>+static void
>+rutabaga_cmd_transfer_to_host_2d(VirtIOGPU *g,
>+                                 struct virtio_gpu_ctrl_command *cmd)
>+{
>+    int32_t result;
>+    struct rutabaga_transfer transfer = { 0 };
>+    struct virtio_gpu_transfer_to_host_2d t2d;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    VIRTIO_GPU_FILL_CMD(t2d);
>+    trace_virtio_gpu_cmd_res_xfer_toh_2d(t2d.resource_id);
>+
>+    transfer.x = t2d.r.x;
>+    transfer.y = t2d.r.y;
>+    transfer.z = 0;
>+    transfer.w = t2d.r.width;
>+    transfer.h = t2d.r.height;
>+    transfer.d = 1;
>+
>+    result = rutabaga_resource_transfer_write(vr->rutabaga, 0, t2d.resource_id,
>+                                              &transfer);
>+    CHECK(!result, cmd);
>+}
>+
>+static void
>+rutabaga_cmd_transfer_to_host_3d(VirtIOGPU *g,
>+                                 struct virtio_gpu_ctrl_command *cmd)
>+{
>+    int32_t result;
>+    struct rutabaga_transfer transfer = { 0 };
>+    struct virtio_gpu_transfer_host_3d t3d;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    VIRTIO_GPU_FILL_CMD(t3d);
>+    trace_virtio_gpu_cmd_res_xfer_toh_3d(t3d.resource_id);
>+
>+    transfer.x = t3d.box.x;
>+    transfer.y = t3d.box.y;
>+    transfer.z = t3d.box.z;
>+    transfer.w = t3d.box.w;
>+    transfer.h = t3d.box.h;
>+    transfer.d = t3d.box.d;
>+    transfer.level = t3d.level;
>+    transfer.stride = t3d.stride;
>+    transfer.layer_stride = t3d.layer_stride;
>+    transfer.offset = t3d.offset;
>+
>+    result = rutabaga_resource_transfer_write(vr->rutabaga, t3d.hdr.ctx_id,
>+                                              t3d.resource_id, &transfer);
>+    CHECK(!result, cmd);
>+}
>+
>+static void
>+rutabaga_cmd_transfer_from_host_3d(VirtIOGPU *g,
>+                                   struct virtio_gpu_ctrl_command *cmd)
>+{
>+    int32_t result;
>+    struct rutabaga_transfer transfer = { 0 };
>+    struct virtio_gpu_transfer_host_3d t3d;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    VIRTIO_GPU_FILL_CMD(t3d);
>+    trace_virtio_gpu_cmd_res_xfer_fromh_3d(t3d.resource_id);
>+
>+    transfer.x = t3d.box.x;
>+    transfer.y = t3d.box.y;
>+    transfer.z = t3d.box.z;
>+    transfer.w = t3d.box.w;
>+    transfer.h = t3d.box.h;
>+    transfer.d = t3d.box.d;
>+    transfer.level = t3d.level;
>+    transfer.stride = t3d.stride;
>+    transfer.layer_stride = t3d.layer_stride;
>+    transfer.offset = t3d.offset;
>+
>+    result = rutabaga_resource_transfer_read(vr->rutabaga, t3d.hdr.ctx_id,
>+                                             t3d.resource_id, &transfer, NULL);
>+    CHECK(!result, cmd);
>+}
>+
>+static void
>+rutabaga_cmd_attach_backing(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd)
>+{
>+    struct rutabaga_iovecs vecs = { 0 };
>+    struct virtio_gpu_simple_resource *res;
>+    struct virtio_gpu_resource_attach_backing att_rb;
>+    int ret;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    VIRTIO_GPU_FILL_CMD(att_rb);
>+    trace_virtio_gpu_cmd_res_back_attach(att_rb.resource_id);
>+
>+    res = virtio_gpu_find_resource(g, att_rb.resource_id);
>+    CHECK(res, cmd);
>+    CHECK(!res->iov, cmd);
>+
>+    ret = virtio_gpu_create_mapping_iov(g, att_rb.nr_entries, sizeof(att_rb),
>+                                        cmd, NULL, &res->iov, &res->iov_cnt);
>+    CHECK(!ret, cmd);
>+
>+    vecs.iovecs = res->iov;
>+    vecs.num_iovecs = res->iov_cnt;
>+
>+    ret = rutabaga_resource_attach_backing(vr->rutabaga, att_rb.resource_id,
>+                                           &vecs);
>+    if (ret != 0) {
>+        virtio_gpu_cleanup_mapping(g, res);
>+    }
>+
>+    CHECK(!ret, cmd);
>+}
>+
>+static void
>+rutabaga_cmd_detach_backing(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd)
>+{
>+    struct virtio_gpu_simple_resource *res;
>+    struct virtio_gpu_resource_detach_backing detach_rb;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    VIRTIO_GPU_FILL_CMD(detach_rb);
>+    trace_virtio_gpu_cmd_res_back_detach(detach_rb.resource_id);
>+
>+    res = virtio_gpu_find_resource(g, detach_rb.resource_id);
>+    CHECK(res, cmd);
>+
>+    rutabaga_resource_detach_backing(vr->rutabaga,
>+                                     detach_rb.resource_id);
>+
>+    virtio_gpu_cleanup_mapping(g, res);
>+}
>+
>+static void
>+rutabaga_cmd_ctx_attach_resource(VirtIOGPU *g,
>+                                 struct virtio_gpu_ctrl_command *cmd)
>+{
>+    int32_t result;
>+    struct virtio_gpu_ctx_resource att_res;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    VIRTIO_GPU_FILL_CMD(att_res);
>+    trace_virtio_gpu_cmd_ctx_res_attach(att_res.hdr.ctx_id,
>+                                        att_res.resource_id);
>+
>+    result = rutabaga_context_attach_resource(vr->rutabaga, att_res.hdr.ctx_id,
>+                                              att_res.resource_id);
>+    CHECK(!result, cmd);
>+}
>+
>+static void
>+rutabaga_cmd_ctx_detach_resource(VirtIOGPU *g,
>+                                 struct virtio_gpu_ctrl_command *cmd)
>+{
>+    int32_t result;
>+    struct virtio_gpu_ctx_resource det_res;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    VIRTIO_GPU_FILL_CMD(det_res);
>+    trace_virtio_gpu_cmd_ctx_res_detach(det_res.hdr.ctx_id,
>+                                        det_res.resource_id);
>+
>+    result = rutabaga_context_detach_resource(vr->rutabaga, det_res.hdr.ctx_id,
>+                                              det_res.resource_id);
>+    CHECK(!result, cmd);
>+}
>+
>+static void
>+rutabaga_cmd_get_capset_info(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd)
>+{
>+    int32_t result;
>+    struct virtio_gpu_get_capset_info info;
>+    struct virtio_gpu_resp_capset_info resp;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    VIRTIO_GPU_FILL_CMD(info);
>+
>+    result = rutabaga_get_capset_info(vr->rutabaga, info.capset_index,
>+                                      &resp.capset_id, &resp.capset_max_version,
>+                                      &resp.capset_max_size);
>+    CHECK(!result, cmd);
>+
>+    resp.hdr.type = VIRTIO_GPU_RESP_OK_CAPSET_INFO;
>+    virtio_gpu_ctrl_response(g, cmd, &resp.hdr, sizeof(resp));
>+}
>+
>+static void
>+rutabaga_cmd_get_capset(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd)
>+{
>+    int32_t result;
>+    struct virtio_gpu_get_capset gc;
>+    struct virtio_gpu_resp_capset *resp;
>+    uint32_t capset_size;
>+    uint32_t current_id;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    VIRTIO_GPU_FILL_CMD(gc);
>+    for (uint32_t i = 0; i < vr->num_capsets; i++) {
>+        CHECK(i < vr->num_capsets, cmd);
>+        result = rutabaga_get_capset_info(vr->rutabaga, i,
>+                                          &current_id, &capset_size,
>+                                          &capset_size);
>+        CHECK(!result, cmd);
>+
>+        if (current_id == gc.capset_id) {
>+            break;
>+        }
>+    }
>+
>+    resp = g_malloc0(sizeof(*resp) + capset_size);
>+    resp->hdr.type = VIRTIO_GPU_RESP_OK_CAPSET;
>+    rutabaga_get_capset(vr->rutabaga, gc.capset_id, gc.capset_version,
>+                        resp->capset_data, capset_size);
>+
>+    virtio_gpu_ctrl_response(g, cmd, &resp->hdr, sizeof(*resp) + capset_size);
>+    g_free(resp);
>+}
>+
>+static void
>+rutabaga_cmd_resource_create_blob(VirtIOGPU *g,
>+                                  struct virtio_gpu_ctrl_command *cmd)
>+{
>+    int result;
>+    struct rutabaga_iovecs vecs = { 0 };
>+    g_autofree struct virtio_gpu_simple_resource *res = NULL;
>+    struct virtio_gpu_resource_create_blob cblob;
>+    struct rutabaga_create_blob rc_blob = { 0 };
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    VIRTIO_GPU_FILL_CMD(cblob);
>+    trace_virtio_gpu_cmd_res_create_blob(cblob.resource_id, cblob.size);
>+
>+    CHECK(cblob.resource_id != 0, cmd);
>+
>+    res = g_new0(struct virtio_gpu_simple_resource, 1);
>+
>+    res->resource_id = cblob.resource_id;
>+    res->blob_size = cblob.size;
>+
>+    if (cblob.blob_mem != VIRTIO_GPU_BLOB_MEM_HOST3D) {
>+        result = virtio_gpu_create_mapping_iov(g, cblob.nr_entries,
>+                                               sizeof(cblob), cmd, &res->addrs,
>+                                               &res->iov, &res->iov_cnt);
>+        CHECK(!result, cmd);
>+    }
>+
>+    rc_blob.blob_id = cblob.blob_id;
>+    rc_blob.blob_mem = cblob.blob_mem;
>+    rc_blob.blob_flags = cblob.blob_flags;
>+    rc_blob.size = cblob.size;
>+
>+    vecs.iovecs = res->iov;
>+    vecs.num_iovecs = res->iov_cnt;
>+
>+    result = rutabaga_resource_create_blob(vr->rutabaga, cblob.hdr.ctx_id,
>+                                           cblob.resource_id, &rc_blob, &vecs,
>+                                           NULL);
>+
>+    if (result && cblob.blob_mem != VIRTIO_GPU_BLOB_MEM_HOST3D) {
>+        virtio_gpu_cleanup_mapping(g, res);
>+    }
>+
>+    CHECK(!result, cmd);
>+
>+    QTAILQ_INSERT_HEAD(&g->reslist, res, next);
>+    res = NULL;
>+}
>+
>+static void
>+rutabaga_cmd_resource_map_blob(VirtIOGPU *g,
>+                               struct virtio_gpu_ctrl_command *cmd)
>+{
>+    int32_t result;
>+    uint32_t map_info = 0;
>+    uint32_t slot = 0;
>+    struct virtio_gpu_simple_resource *res;
>+    struct rutabaga_mapping mapping = { 0 };
>+    struct virtio_gpu_resource_map_blob mblob;
>+    struct virtio_gpu_resp_map_info resp = { 0 };
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    VIRTIO_GPU_FILL_CMD(mblob);
>+
>+    CHECK(mblob.resource_id != 0, cmd);
>+
>+    res = virtio_gpu_find_resource(g, mblob.resource_id);
>+    CHECK(res, cmd);
>+
>+    result = rutabaga_resource_map_info(vr->rutabaga, mblob.resource_id,
>+                                        &map_info);
>+    CHECK(!result, cmd);
>+
>+    /*
>+     * RUTABAGA_MAP_ACCESS_* flags are not part of the virtio-gpu spec, but do
>+     * exist to potentially allow the hypervisor to restrict write access to
>+     * memory. QEMU does not need to use this functionality at the moment.
>+     */
>+    resp.map_info = map_info & RUTABAGA_MAP_CACHE_MASK;
>+
>+    result = rutabaga_resource_map(vr->rutabaga, mblob.resource_id, &mapping);
>+    CHECK(!result, cmd);
>+
>+    for (slot = 0; slot < MAX_SLOTS; slot++) {
>+        if (vr->memory_regions[slot].used) {
>+            continue;
>+        }
>+
>+        MemoryRegion *mr = &(vr->memory_regions[slot].mr);
>+        memory_region_init_ram_ptr(mr, NULL, "blob", mapping.size,
>+                                   mapping.ptr);
>+        memory_region_add_subregion(&g->parent_obj.hostmem,
>+                                    mblob.offset, mr);
>+        vr->memory_regions[slot].resource_id = mblob.resource_id;
>+        vr->memory_regions[slot].used = 1;
>+        break;
>+    }
>+
>+    if (slot >= MAX_SLOTS) {
>+        result = rutabaga_resource_unmap(vr->rutabaga, mblob.resource_id);
>+        CHECK(!result, cmd);
>+    }
>+
>+    CHECK(slot < MAX_SLOTS, cmd);
>+
>+    resp.hdr.type = VIRTIO_GPU_RESP_OK_MAP_INFO;
>+    virtio_gpu_ctrl_response(g, cmd, &resp.hdr, sizeof(resp));
>+}
>+
>+static void
>+rutabaga_cmd_resource_unmap_blob(VirtIOGPU *g,
>+                                 struct virtio_gpu_ctrl_command *cmd)
>+{
>+    int32_t result;
>+    uint32_t slot = 0;
>+    struct virtio_gpu_simple_resource *res;
>+    struct virtio_gpu_resource_unmap_blob ublob;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    VIRTIO_GPU_FILL_CMD(ublob);
>+
>+    CHECK(ublob.resource_id != 0, cmd);
>+
>+    res = virtio_gpu_find_resource(g, ublob.resource_id);
>+    CHECK(res, cmd);
>+
>+    for (slot = 0; slot < MAX_SLOTS; slot++) {
>+        if (vr->memory_regions[slot].resource_id != ublob.resource_id) {
>+            continue;
>+        }
>+
>+        MemoryRegion *mr = &(vr->memory_regions[slot].mr);
>+        memory_region_del_subregion(&g->parent_obj.hostmem, mr);
>+
>+        vr->memory_regions[slot].resource_id = 0;
>+        vr->memory_regions[slot].used = 0;
>+        break;
>+    }
>+
>+    CHECK(slot < MAX_SLOTS, cmd);
>+    result = rutabaga_resource_unmap(vr->rutabaga, res->resource_id);
>+    CHECK(!result, cmd);
>+}
>+
>+static void
>+virtio_gpu_rutabaga_process_cmd(VirtIOGPU *g,
>+                                struct virtio_gpu_ctrl_command *cmd)
>+{
>+    struct rutabaga_fence fence = { 0 };
>+    int32_t result;
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    VIRTIO_GPU_FILL_CMD(cmd->cmd_hdr);
>+
>+    switch (cmd->cmd_hdr.type) {
>+    case VIRTIO_GPU_CMD_CTX_CREATE:
>+        rutabaga_cmd_context_create(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_CTX_DESTROY:
>+        rutabaga_cmd_context_destroy(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_RESOURCE_CREATE_2D:
>+        rutabaga_cmd_create_resource_2d(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_RESOURCE_CREATE_3D:
>+        rutabaga_cmd_create_resource_3d(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_SUBMIT_3D:
>+        rutabaga_cmd_submit_3d(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_TRANSFER_TO_HOST_2D:
>+        rutabaga_cmd_transfer_to_host_2d(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_TRANSFER_TO_HOST_3D:
>+        rutabaga_cmd_transfer_to_host_3d(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_TRANSFER_FROM_HOST_3D:
>+        rutabaga_cmd_transfer_from_host_3d(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_RESOURCE_ATTACH_BACKING:
>+        rutabaga_cmd_attach_backing(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_RESOURCE_DETACH_BACKING:
>+        rutabaga_cmd_detach_backing(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_SET_SCANOUT:
>+        rutabaga_cmd_set_scanout(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_RESOURCE_FLUSH:
>+        rutabaga_cmd_resource_flush(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_RESOURCE_UNREF:
>+        rutabaga_cmd_resource_unref(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_CTX_ATTACH_RESOURCE:
>+        rutabaga_cmd_ctx_attach_resource(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_CTX_DETACH_RESOURCE:
>+        rutabaga_cmd_ctx_detach_resource(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_GET_CAPSET_INFO:
>+        rutabaga_cmd_get_capset_info(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_GET_CAPSET:
>+        rutabaga_cmd_get_capset(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_GET_DISPLAY_INFO:
>+        virtio_gpu_get_display_info(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_GET_EDID:
>+        virtio_gpu_get_edid(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_RESOURCE_CREATE_BLOB:
>+        rutabaga_cmd_resource_create_blob(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_RESOURCE_MAP_BLOB:
>+        rutabaga_cmd_resource_map_blob(g, cmd);
>+        break;
>+    case VIRTIO_GPU_CMD_RESOURCE_UNMAP_BLOB:
>+        rutabaga_cmd_resource_unmap_blob(g, cmd);
>+        break;
>+    default:
>+        cmd->error = VIRTIO_GPU_RESP_ERR_UNSPEC;
>+        break;
>+    }
>+
>+    if (cmd->finished) {
>+        return;
>+    }
>+    if (cmd->error) {
>+        error_report("%s: ctrl 0x%x, error 0x%x", __func__,
>+                     cmd->cmd_hdr.type, cmd->error);
>+        virtio_gpu_ctrl_response_nodata(g, cmd, cmd->error);
>+        return;
>+    }
>+    if (!(cmd->cmd_hdr.flags & VIRTIO_GPU_FLAG_FENCE)) {
>+        virtio_gpu_ctrl_response_nodata(g, cmd, VIRTIO_GPU_RESP_OK_NODATA);
>+        return;
>+    }
>+
>+    fence.flags = cmd->cmd_hdr.flags;
>+    fence.ctx_id = cmd->cmd_hdr.ctx_id;
>+    fence.fence_id = cmd->cmd_hdr.fence_id;
>+    fence.ring_idx = cmd->cmd_hdr.ring_idx;
>+
>+    trace_virtio_gpu_fence_ctrl(cmd->cmd_hdr.fence_id, cmd->cmd_hdr.type);
>+
>+    result = rutabaga_create_fence(vr->rutabaga, &fence);
>+    CHECK(!result, cmd);
>+}
>+
>+static void
>+virtio_gpu_rutabaga_aio_cb(void *opaque)
>+{
>+    struct rutabaga_aio_data *data = opaque;
>+    VirtIOGPU *g = VIRTIO_GPU(data->vr);
>+    struct rutabaga_fence fence_data = data->fence;
>+    struct virtio_gpu_ctrl_command *cmd, *tmp;
>+
>+    uint32_t signaled_ctx_specific = fence_data.flags &
>+                                     RUTABAGA_FLAG_INFO_RING_IDX;
>+
>+    QTAILQ_FOREACH_SAFE(cmd, &g->fenceq, next, tmp) {
>+        /*
>+         * Due to context specific timelines.
>+         */
>+        uint32_t target_ctx_specific = cmd->cmd_hdr.flags &
>+                                       RUTABAGA_FLAG_INFO_RING_IDX;
>+
>+        if (signaled_ctx_specific != target_ctx_specific) {
>+            continue;
>+        }
>+
>+        if (signaled_ctx_specific &&
>+           (cmd->cmd_hdr.ring_idx != fence_data.ring_idx)) {
>+            continue;
>+        }
>+
>+        if (cmd->cmd_hdr.fence_id > fence_data.fence_id) {
>+            continue;
>+        }
>+
>+        trace_virtio_gpu_fence_resp(cmd->cmd_hdr.fence_id);
>+        virtio_gpu_ctrl_response_nodata(g, cmd, VIRTIO_GPU_RESP_OK_NODATA);
>+        QTAILQ_REMOVE(&g->fenceq, cmd, next);
>+        g_free(cmd);
>+    }
>+
>+    g_free(data);
>+}
>+
>+static void
>+virtio_gpu_rutabaga_fence_cb(uint64_t user_data,
>+                             const struct rutabaga_fence *fence) {
>+    struct rutabaga_aio_data *data;
>+    VirtIOGPU *g = (VirtIOGPU *)user_data;
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    /*
>+     * gfxstream and both cross-domain (and even newer versions virglrenderer:
>+     * see VIRGL_RENDERER_ASYNC_FENCE_CB) like to signal fence completion on
>+     * threads ("callback threads") that are different from the thread that
>+     * processes the command queue ("main thread").
>+     *
>+     * crosvm and other virtio-gpu 1.1 implementations enable callback threads
>+     * via locking.  However, on QEMU a deadlock is observed if
>+     * virtio_gpu_ctrl_response_nodata(..) [used in the fence callback] is used
>+     * from a thread that is not the main thread.
>+     *
>+     * The reason is QEMU's internal locking is designed to work with QEMU
>+     * threads (see rcu_register_thread()) and not generic C/C++/Rust threads.
>+     * For now, we can workaround this by scheduling the return of the
>+     * fence descriptors on the main thread.
>+     */
>+
>+    data = g_new0(struct rutabaga_aio_data, 1);
>+    data->vr = vr;
>+    data->fence = *fence;
>+    aio_bh_schedule_oneshot_full(qemu_get_aio_context(),
>+                                 virtio_gpu_rutabaga_aio_cb,
>+                                 data, "aio");
>+}
>+
>+static void
>+virtio_gpu_rutabaga_debug_cb(uint64_t user_data,
>+                             const struct rutabaga_debug *debug) {
>+
>+    if (debug->debug_type == RUTABAGA_DEBUG_ERROR) {
>+        error_report("%s", debug->message);
>+    } else if (debug->debug_type == RUTABAGA_DEBUG_WARN) {
>+        warn_report("%s", debug->message);
>+    } else if (debug->debug_type == RUTABAGA_DEBUG_INFO) {
>+        info_report("%s", debug->message);
>+    }
>+}
>+
>+static int virtio_gpu_rutabaga_init(VirtIOGPU *g, Error **errp)
>+{
>+    int result;
>+    uint64_t capset_mask;
>+    struct rutabaga_builder builder = { 0 };
>+    char wayland_socket_path[UNIX_PATH_MAX];
>+    struct rutabaga_channel channel = { 0 };
>+    struct rutabaga_channels channels = { 0 };
>+
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+    vr->rutabaga = NULL;
>+
>+    if (!vr->capset_names) {
>+        error_setg(errp, "a capset name from the virtio-gpu spec is required");
>+        return -EINVAL;
>+    }
>+
>+    builder.wsi = RUTABAGA_WSI_SURFACELESS;
>+    /*
>+     * Currently, if WSI is specified, the only valid strings are "surfaceless"
>+     * or "headless".  Surfaceless doesn't create a native window surface, but
>+     * does copy from the render target to the Pixman buffer if a virtio-gpu
>+     * 2D hypercall is issued.  Surfacless is the default.
>+     *
>+     * Headless is like surfaceless, but doesn't copy to the Pixman buffer. The
>+     * use case is automated testing environments where there is no need to view
>+     * results.
>+     *
>+     * In the future, more performant virtio-gpu 2D UI integration may be added.
>+     */
>+    if (vr->wsi) {
>+        if (g_str_equal(vr->wsi, "surfaceless")) {
>+            vr->headless = false;
>+        } else if (g_str_equal(vr->wsi, "headless")) {
>+            vr->headless = true;
>+        } else {
>+            error_setg(errp, "invalid wsi option selected");
>+            return -EINVAL;
>+        }
>+    }
>+
>+    result = rutabaga_calculate_capset_mask(vr->capset_names, &capset_mask);
>+    if (result) {
>+        error_setg(errp, "invalid capset names: %s", vr->capset_names);
>+        return result;
>+    }
>+
>+    builder.fence_cb = virtio_gpu_rutabaga_fence_cb;
>+    builder.debug_cb = virtio_gpu_rutabaga_debug_cb;
>+    builder.capset_mask = capset_mask;
>+    builder.user_data = (uint64_t)g;
>+
>+    /*
>+     * If the user doesn't specify the wayland socket path, we try to infer
>+     * the socket via a process similar to the one used by libwayland.
>+     * libwayland does the following:
>+     *
>+     * 1) If $WAYLAND_DISPLAY is set, attempt to connect to
>+     *    $XDG_RUNTIME_DIR/$WAYLAND_DISPLAY
>+     * 2) Otherwise, attempt to connect to $XDG_RUNTIME_DIR/wayland-0
>+     * 3) Otherwise, don't pass a wayland socket to rutabaga. If a guest
>+     *    wayland proxy is launched, it will fail to work.
>+     */
>+    channel.channel_type = RUTABAGA_CHANNEL_TYPE_WAYLAND;
>+    if (!vr->wayland_socket_path) {
>+        const char *runtime_dir = getenv("XDG_RUNTIME_DIR");
>+        const char *display = getenv("WAYLAND_DISPLAY");
>+        if (!display) {
>+            display = "wayland-0";
>+        }
>+
>+        if (runtime_dir) {
>+            result = snprintf(wayland_socket_path, UNIX_PATH_MAX,
>+                              "%s/%s", runtime_dir, display);
>+            if (result > 0 && result < UNIX_PATH_MAX) {
>+                channel.channel_name = wayland_socket_path;
>+            }
>+        }
>+    } else {
>+        channel.channel_name = vr->wayland_socket_path;
>+    }
>+
>+    if ((builder.capset_mask & (1 << RUTABAGA_CAPSET_CROSS_DOMAIN))) {
>+        if (channel.channel_name) {
>+            channels.channels = &channel;
>+            channels.num_channels = 1;
>+            builder.channels = &channels;
>+        }
>+    }
>+
>+    result = rutabaga_init(&builder, &vr->rutabaga);
>+    return result;
>+}
>+
>+static int virtio_gpu_rutabaga_get_num_capsets(VirtIOGPU *g)
>+{
>+    int result;
>+    uint32_t num_capsets;
>+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>+
>+    result = rutabaga_get_num_capsets(vr->rutabaga, &num_capsets);
>+    if (result) {
>+        error_report("Failed to get capsets");
>+        return 0;
>+    }
>+    vr->num_capsets = num_capsets;
>+    return num_capsets;
>+}
>+
>+static void virtio_gpu_rutabaga_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
>+{
>+    VirtIOGPU *g = VIRTIO_GPU(vdev);
>+    struct virtio_gpu_ctrl_command *cmd;
>+
>+    if (!virtio_queue_ready(vq)) {
>+        return;
>+    }
>+
>+    cmd = virtqueue_pop(vq, sizeof(struct virtio_gpu_ctrl_command));
>+    while (cmd) {
>+        cmd->vq = vq;
>+        cmd->error = 0;
>+        cmd->finished = false;
>+        QTAILQ_INSERT_TAIL(&g->cmdq, cmd, next);
>+        cmd = virtqueue_pop(vq, sizeof(struct virtio_gpu_ctrl_command));
>+    }
>+
>+    virtio_gpu_process_cmdq(g);
>+}
>+
>+static void virtio_gpu_rutabaga_realize(DeviceState *qdev, Error **errp)
>+{
>+    int num_capsets;
>+    VirtIOGPUBase *bdev = VIRTIO_GPU_BASE(qdev);
>+    VirtIOGPU *gpudev = VIRTIO_GPU(qdev);
>+
>+#if HOST_BIG_ENDIAN
>+    error_setg(errp, "rutabaga is not supported on bigendian platforms");
>+    return;
>+#endif
>+
>+    int result = virtio_gpu_rutabaga_init(gpudev, errp);
>+    if (result) {
>+        error_setg(errp, "virtio_gpu_rutabaga_init failed");
>+        return;
>+    }
>+
>+    num_capsets = virtio_gpu_rutabaga_get_num_capsets(gpudev);
>+    if (!num_capsets) {
>+        return;
>+    }
>+
>+    bdev->conf.flags |= (1 << VIRTIO_GPU_FLAG_RUTABAGA_ENABLED);
>+    bdev->conf.flags |= (1 << VIRTIO_GPU_FLAG_BLOB_ENABLED);
>+    bdev->conf.flags |= (1 << VIRTIO_GPU_FLAG_CONTEXT_INIT_ENABLED);
>+
>+    bdev->virtio_config.num_capsets = num_capsets;
>+    virtio_gpu_device_realize(qdev, errp);
>+}
>+
>+static Property virtio_gpu_rutabaga_properties[] = {
>+    DEFINE_PROP_STRING("capset_names", VirtIOGPURutabaga, capset_names),
>+    DEFINE_PROP_STRING("wayland_socket_path", VirtIOGPURutabaga,
>+                       wayland_socket_path),
>+    DEFINE_PROP_STRING("wsi", VirtIOGPURutabaga, wsi),
>+    DEFINE_PROP_END_OF_LIST(),
>+};
>+
>+static void virtio_gpu_rutabaga_class_init(ObjectClass *klass, void *data)
>+{
>+    DeviceClass *dc = DEVICE_CLASS(klass);
>+    VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
>+    VirtIOGPUBaseClass *vbc = VIRTIO_GPU_BASE_CLASS(klass);
>+    VirtIOGPUClass *vgc = VIRTIO_GPU_CLASS(klass);
>+
>+    vbc->gl_flushed = virtio_gpu_rutabaga_gl_flushed;
>+    vgc->handle_ctrl = virtio_gpu_rutabaga_handle_ctrl;
>+    vgc->process_cmd = virtio_gpu_rutabaga_process_cmd;
>+    vgc->update_cursor_data = virtio_gpu_rutabaga_update_cursor;
>+
>+    vdc->realize = virtio_gpu_rutabaga_realize;
>+    device_class_set_props(dc, virtio_gpu_rutabaga_properties);
>+}
>+
>+static const TypeInfo virtio_gpu_rutabaga_info = {
>+    .name = TYPE_VIRTIO_GPU_RUTABAGA,
>+    .parent = TYPE_VIRTIO_GPU,
>+    .instance_size = sizeof(VirtIOGPURutabaga),
>+    .class_init = virtio_gpu_rutabaga_class_init,
>+};
>+module_obj(TYPE_VIRTIO_GPU_RUTABAGA);
>+module_kconfig(VIRTIO_GPU);
>+
>+static void virtio_register_types(void)
>+{
>+    type_register_static(&virtio_gpu_rutabaga_info);
>+}
>+
>+type_init(virtio_register_types)
>+
>+module_dep("hw-display-virtio-gpu");
>diff --git a/hw/display/virtio-vga-rutabaga.c b/hw/display/virtio-vga-rutabaga.c
>new file mode 100644
>index 0000000000..2b2ffed8a6
>--- /dev/null
>+++ b/hw/display/virtio-vga-rutabaga.c
>@@ -0,0 +1,51 @@
>+// SPDX-License-Identifier: GPL-2.0
>+
>+#include "qemu/osdep.h"
>+#include "hw/pci/pci.h"
>+#include "hw/qdev-properties.h"
>+#include "hw/virtio/virtio-gpu.h"
>+#include "hw/display/vga.h"
>+#include "qapi/error.h"
>+#include "qemu/module.h"
>+#include "virtio-vga.h"
>+#include "qom/object.h"
>+
>+#define TYPE_VIRTIO_VGA_RUTABAGA "virtio-vga-rutabaga"
>+
>+typedef struct VirtIOVGARutabaga VirtIOVGARutabaga;
>+DECLARE_INSTANCE_CHECKER(VirtIOVGARutabaga, VIRTIO_VGA_RUTABAGA,
>+                         TYPE_VIRTIO_VGA_RUTABAGA)
>+
>+struct VirtIOVGARutabaga {
>+    VirtIOVGABase parent_obj;
>+    VirtIOGPURutabaga vdev;
>+};
>+
>+static void virtio_vga_rutabaga_inst_initfn(Object *obj)
>+{
>+    VirtIOVGARutabaga *dev = VIRTIO_VGA_RUTABAGA(obj);
>+
>+    virtio_instance_init_common(obj, &dev->vdev, sizeof(dev->vdev),
>+                                TYPE_VIRTIO_GPU_RUTABAGA);
>+    VIRTIO_VGA_BASE(dev)->vgpu = VIRTIO_GPU_BASE(&dev->vdev);
>+}
>+
>+static VirtioPCIDeviceTypeInfo virtio_vga_rutabaga_info = {
>+    .generic_name  = TYPE_VIRTIO_VGA_RUTABAGA,
>+    .parent        = TYPE_VIRTIO_VGA_BASE,
>+    .instance_size = sizeof(VirtIOVGARutabaga),
>+    .instance_init = virtio_vga_rutabaga_inst_initfn,
>+};
>+module_obj(TYPE_VIRTIO_VGA_RUTABAGA);
>+module_kconfig(VIRTIO_VGA);
>+
>+static void virtio_vga_register_types(void)
>+{
>+    if (have_vga) {
>+        virtio_pci_types_register(&virtio_vga_rutabaga_info);
>+    }
>+}
>+
>+type_init(virtio_vga_register_types)
>+
>+module_dep("hw-display-virtio-vga");
>-- 
>2.41.0.694.ge786442a9b-goog
>
>

Akihiko Odaki Aug. 15, 2023, 3:07 p.m. UTC | #2

On 2023/08/15 9:35, Gurchetan Singh wrote:
> This adds initial support for gfxstream and cross-domain.  Both
> features rely on virtio-gpu blob resources and context types, which
> are also implemented in this patch.
> 
> gfxstream has a long and illustrious history in Android graphics
> paravirtualization.  It has been powering graphics in the Android
> Studio Emulator for more than a decade, which is the main developer
> platform.
> 
> Originally conceived by Jesse Hall, it was first known as "EmuGL" [a].
> The key design characteristic was a 1:1 threading model and
> auto-generation, which fit nicely with the OpenGLES spec.  It also
> allowed easy layering with ANGLE on the host, which provides the GLES
> implementations on Windows or MacOS enviroments.
> 
> gfxstream has traditionally been maintained by a single engineer, and
> between 2015 to 2021, the goldfish throne passed to Frank Yang.
> Historians often remark this glorious reign ("pax gfxstreama" is the
> academic term) was comparable to that of Augustus and both Queen
> Elizabeths.  Just to name a few accomplishments in a resplendent
> panoply: higher versions of GLES, address space graphics, snapshot
> support and CTS compliant Vulkan [b].
> 
> One major drawback was the use of out-of-tree goldfish drivers.
> Android engineers didn't know much about DRM/KMS and especially TTM so
> a simple guest to host pipe was conceived.
> 
> Luckily, virtio-gpu 3D started to emerge in 2016 due to the work of
> the Mesa/virglrenderer communities.  In 2018, the initial virtio-gpu
> port of gfxstream was done by Cuttlefish enthusiast Alistair Delva.
> It was a symbol compatible replacement of virglrenderer [c] and named
> "AVDVirglrenderer".  This implementation forms the basis of the
> current gfxstream host implementation still in use today.
> 
> cross-domain support follows a similar arc.  Originally conceived by
> Wayland aficionado David Reveman and crosvm enjoyer Zach Reizner in
> 2018, it initially relied on the downstream "virtio-wl" device.
> 
> In 2020 and 2021, virtio-gpu was extended to include blob resources
> and multiple timelines by yours truly, features gfxstream/cross-domain
> both require to function correctly.
> 
> Right now, we stand at the precipice of a truly fantastic possibility:
> the Android Emulator powered by upstream QEMU and upstream Linux
> kernel.  gfxstream will then be packaged properfully, and app
> developers can even fix gfxstream bugs on their own if they encounter
> them.
> 
> It's been quite the ride, my friends.  Where will gfxstream head next,
> nobody really knows.  I wouldn't be surprised if it's around for
> another decade, maintained by a new generation of Android graphics
> enthusiasts.
> 
> Technical details:
>    - Very simple initial display integration: just used Pixman
>    - Largely, 1:1 mapping of virtio-gpu hypercalls to rutabaga function
>      calls
> 
> Next steps for Android VMs:
>    - The next step would be improving display integration and UI interfaces
>      with the goal of the QEMU upstream graphics being in an emulator
>      release [d].
> 
> Next steps for Linux VMs for display virtualization:
>    - For widespread distribution, someone needs to package Sommelier or the
>      wayland-proxy-virtwl [e] ideally into Debian main. In addition, newer
>      versions of the Linux kernel come with DRM_VIRTIO_GPU_KMS option,
>      which allows disabling KMS hypercalls.  If anyone cares enough, it'll
>      probably be possible to build a custom VM variant that uses this display
>      virtualization strategy.
> 
> [a] https://android-review.googlesource.com/c/platform/development/+/34470
> [b] https://android-review.googlesource.com/q/topic:%22vulkan-hostconnection-start%22
> [c] https://android-review.googlesource.com/c/device/generic/goldfish-opengl/+/761927
> [d] https://developer.android.com/studio/releases/emulator
> [e] https://github.com/talex5/wayland-proxy-virtwl
> 
> Signed-off-by: Gurchetan Singh <[e-mail]>
> Tested-by: Alyssa Ross <[e-mail]>
> ---
> v1: Incorported various suggestions by Akihiko Odaki and Bernard Berschow
>      - Removed GET_VIRTIO_GPU_GL / GET_RUTABAGA macros
>      - Used error_report(..)
>      - Used g_autofree to fix leaks on error paths
>      - Removed unnecessary casts
>      - added virtio-gpu-pci-rutabaga.c + virtio-vga-rutabaga.c files
> 
> v2: Incorported various suggestions by Akihiko Odaki, Marc-André Lureau and
>      Bernard Berschow:
>      - Parenthesis in CHECK macro
>      - CHECK_RESULT(result, ..) --> CHECK(!result, ..)
>      - delay until g->parent_obj.enable = 1
>      - Additional cast fixes
>      - initialize directly in virtio_gpu_rutabaga_realize(..)
>      - add debug callback to hook into QEMU error's APIs
> 
> v3: Incorporated feedback from Akihiko Odaki and Alyssa Ross:
>      - Autodetect Wayland socket when not explicitly specified
>      - Fix map_blob error paths
>      - Add comment why we need both `res` and `resource` in create blob
>      - Cast and whitespace fixes
>      - Big endian check comes before virtio_gpu_rutabaga_init().
>      - VirtIOVGARUTABAGA --> VirtIOVGARutabaga
> 
> v4: Incorporated feedback from Akihiko Odaki and Alyssa Ross:
>      - Double checked all casts
>      - Remove unnecessary parenthesis
>      - Removed `resource` in create_blob
>      - Added comment about failure case
>      - Pass user-provided socket as-is
>      - Use stack variable rather than heap allocation
>      - Future-proofed map info API to give access flags as well
> 
> v5: Incorporated feedback from Akihiko Odaki:
>      - Check (ss.scanout_id < VIRTIO_GPU_MAX_SCANOUTS)
>      - Simplify num_capsets check
>      - Call cleanup mapping on error paths
>      - uint64_t --> void* for rutabaga_map(..)
>      - Removed unnecessary parenthesis
>      - Removed unnecessary cast
>      - #define UNIX_PATH_MAX sizeof((struct sockaddr_un) {}.sun_path)
>      - Reuse result variable
>      - Report error when default socket doesn't fit in Wayland socket path
> 
>   hw/display/virtio-gpu-pci-rutabaga.c |   48 ++
>   hw/display/virtio-gpu-rutabaga.c     | 1114 ++++++++++++++++++++++++++
>   hw/display/virtio-vga-rutabaga.c     |   51 ++
>   3 files changed, 1213 insertions(+)
>   create mode 100644 hw/display/virtio-gpu-pci-rutabaga.c
>   create mode 100644 hw/display/virtio-gpu-rutabaga.c
>   create mode 100644 hw/display/virtio-vga-rutabaga.c
> 
> diff --git a/hw/display/virtio-gpu-pci-rutabaga.c b/hw/display/virtio-gpu-pci-rutabaga.c
> new file mode 100644
> index 0000000000..c71173d8ca
> --- /dev/null
> +++ b/hw/display/virtio-gpu-pci-rutabaga.c
> @@ -0,0 +1,48 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include "qemu/osdep.h"
> +#include "qapi/error.h"
> +#include "qemu/module.h"
> +#include "hw/pci/pci.h"
> +#include "hw/qdev-properties.h"
> +#include "hw/virtio/virtio.h"
> +#include "hw/virtio/virtio-bus.h"
> +#include "hw/virtio/virtio-gpu-pci.h"
> +#include "qom/object.h"
> +
> +#define TYPE_VIRTIO_GPU_RUTABAGA_PCI "virtio-gpu-rutabaga-pci"
> +typedef struct VirtIOGPURutabagaPCI VirtIOGPURutabagaPCI;
> +DECLARE_INSTANCE_CHECKER(VirtIOGPURutabagaPCI, VIRTIO_GPU_RUTABAGA_PCI,
> +                         TYPE_VIRTIO_GPU_RUTABAGA_PCI)
> +
> +struct VirtIOGPURutabagaPCI {
> +    VirtIOGPUPCIBase parent_obj;
> +    VirtIOGPURutabaga vdev;
> +};
> +
> +static void virtio_gpu_rutabaga_initfn(Object *obj)
> +{
> +    VirtIOGPURutabagaPCI *dev = VIRTIO_GPU_RUTABAGA_PCI(obj);
> +
> +    virtio_instance_init_common(obj, &dev->vdev, sizeof(dev->vdev),
> +                                TYPE_VIRTIO_GPU_RUTABAGA);
> +    VIRTIO_GPU_PCI_BASE(obj)->vgpu = VIRTIO_GPU_BASE(&dev->vdev);
> +}
> +
> +static const VirtioPCIDeviceTypeInfo virtio_gpu_rutabaga_pci_info = {
> +    .generic_name = TYPE_VIRTIO_GPU_RUTABAGA_PCI,
> +    .parent = TYPE_VIRTIO_GPU_PCI_BASE,
> +    .instance_size = sizeof(VirtIOGPURutabagaPCI),
> +    .instance_init = virtio_gpu_rutabaga_initfn,
> +};
> +module_obj(TYPE_VIRTIO_GPU_RUTABAGA_PCI);
> +module_kconfig(VIRTIO_PCI);
> +
> +static void virtio_gpu_rutabaga_pci_register_types(void)
> +{
> +    virtio_pci_types_register(&virtio_gpu_rutabaga_pci_info);
> +}
> +
> +type_init(virtio_gpu_rutabaga_pci_register_types)
> +
> +module_dep("hw-display-virtio-gpu-pci");
> diff --git a/hw/display/virtio-gpu-rutabaga.c b/hw/display/virtio-gpu-rutabaga.c
> new file mode 100644
> index 0000000000..3f9f106abc
> --- /dev/null
> +++ b/hw/display/virtio-gpu-rutabaga.c
> @@ -0,0 +1,1114 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include "qemu/osdep.h"
> +#include "qapi/error.h"
> +#include "qemu/error-report.h"
> +#include "qemu/iov.h"
> +#include "trace.h"
> +#include "hw/virtio/virtio.h"
> +#include "hw/virtio/virtio-gpu.h"
> +#include "hw/virtio/virtio-gpu-pixman.h"
> +#include "hw/virtio/virtio-iommu.h"
> +
> +#include <glib/gmem.h>
> +#include <rutabaga_gfx/rutabaga_gfx_ffi.h>
> +
> +#define CHECK(condition, cmd)                                                 \
> +    do {                                                                      \
> +        if (!(condition)) {                                                   \
> +            error_report("CHECK failed in %s() %s:" "%d", __func__,           \
> +                         __FILE__, __LINE__);                                 \
> +            (cmd)->error = VIRTIO_GPU_RESP_ERR_UNSPEC;                        \
> +            return;                                                           \
> +       }                                                                      \
> +    } while (0)
> +
> +/*
> + * This is the size of the char array in struct sock_addr_un. No Wayland socket
> + * can be created with a path longer than this, including the null terminator.
> + */
> +#ifndef UNIX_PATH_MAX

You shouldn't need this ifndef.

> +#define UNIX_PATH_MAX sizeof((struct sockaddr_un) {} .sun_path)
> +#endif
> +
> +struct rutabaga_aio_data {
> +    struct VirtIOGPURutabaga *vr;
> +    struct rutabaga_fence fence;
> +};
> +
> +static void
> +virtio_gpu_rutabaga_update_cursor(VirtIOGPU *g, struct virtio_gpu_scanout *s,
> +                                  uint32_t resource_id)
> +{
> +    struct virtio_gpu_simple_resource *res;
> +    struct rutabaga_transfer transfer = { 0 };
> +    struct iovec transfer_iovec;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    res = virtio_gpu_find_resource(g, resource_id);
> +    if (!res) {
> +        return;
> +    }
> +
> +    if (res->width != s->current_cursor->width ||
> +        res->height != s->current_cursor->height) {
> +        return;
> +    }
> +
> +    transfer.x = 0;
> +    transfer.y = 0;
> +    transfer.z = 0;
> +    transfer.w = res->width;
> +    transfer.h = res->height;
> +    transfer.d = 1;
> +
> +    transfer_iovec.iov_base = s->current_cursor->data;
> +    transfer_iovec.iov_len = res->width * res->height * 4;
> +
> +    rutabaga_resource_transfer_read(vr->rutabaga, 0,
> +                                    resource_id, &transfer,
> +                                    &transfer_iovec);
> +}
> +
> +static void
> +virtio_gpu_rutabaga_gl_flushed(VirtIOGPUBase *b)
> +{
> +    VirtIOGPU *g = VIRTIO_GPU(b);
> +    virtio_gpu_process_cmdq(g);
> +}
> +
> +static void
> +rutabaga_cmd_create_resource_2d(VirtIOGPU *g,
> +                                struct virtio_gpu_ctrl_command *cmd)
> +{
> +    int32_t result;
> +    struct rutabaga_create_3d rc_3d = { 0 };
> +    struct virtio_gpu_simple_resource *res;
> +    struct virtio_gpu_resource_create_2d c2d;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    VIRTIO_GPU_FILL_CMD(c2d);
> +    trace_virtio_gpu_cmd_res_create_2d(c2d.resource_id, c2d.format,
> +                                       c2d.width, c2d.height);
> +
> +    rc_3d.target = 2;
> +    rc_3d.format = c2d.format;
> +    rc_3d.bind = (1 << 1);
> +    rc_3d.width = c2d.width;
> +    rc_3d.height = c2d.height;
> +    rc_3d.depth = 1;
> +    rc_3d.array_size = 1;
> +    rc_3d.last_level = 0;
> +    rc_3d.nr_samples = 0;
> +    rc_3d.flags = VIRTIO_GPU_RESOURCE_FLAG_Y_0_TOP;
> +
> +    result = rutabaga_resource_create_3d(vr->rutabaga, c2d.resource_id, &rc_3d);
> +    CHECK(!result, cmd);
> +
> +    res = g_new0(struct virtio_gpu_simple_resource, 1);
> +    res->width = c2d.width;
> +    res->height = c2d.height;
> +    res->format = c2d.format;
> +    res->resource_id = c2d.resource_id;
> +
> +    QTAILQ_INSERT_HEAD(&g->reslist, res, next);
> +}
> +
> +static void
> +rutabaga_cmd_create_resource_3d(VirtIOGPU *g,
> +                                struct virtio_gpu_ctrl_command *cmd)
> +{
> +    int32_t result;
> +    struct rutabaga_create_3d rc_3d = { 0 };
> +    struct virtio_gpu_simple_resource *res;
> +    struct virtio_gpu_resource_create_3d c3d;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    VIRTIO_GPU_FILL_CMD(c3d);
> +
> +    trace_virtio_gpu_cmd_res_create_3d(c3d.resource_id, c3d.format,
> +                                       c3d.width, c3d.height, c3d.depth);
> +
> +    rc_3d.target = c3d.target;
> +    rc_3d.format = c3d.format;
> +    rc_3d.bind = c3d.bind;
> +    rc_3d.width = c3d.width;
> +    rc_3d.height = c3d.height;
> +    rc_3d.depth = c3d.depth;
> +    rc_3d.array_size = c3d.array_size;
> +    rc_3d.last_level = c3d.last_level;
> +    rc_3d.nr_samples = c3d.nr_samples;
> +    rc_3d.flags = c3d.flags;
> +
> +    result = rutabaga_resource_create_3d(vr->rutabaga, c3d.resource_id, &rc_3d);
> +    CHECK(!result, cmd);
> +
> +    res = g_new0(struct virtio_gpu_simple_resource, 1);
> +    res->width = c3d.width;
> +    res->height = c3d.height;
> +    res->format = c3d.format;
> +    res->resource_id = c3d.resource_id;
> +
> +    QTAILQ_INSERT_HEAD(&g->reslist, res, next);
> +}
> +
> +static void
> +rutabaga_cmd_resource_unref(VirtIOGPU *g,
> +                            struct virtio_gpu_ctrl_command *cmd)
> +{
> +    int32_t result;
> +    struct virtio_gpu_simple_resource *res;
> +    struct virtio_gpu_resource_unref unref;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    VIRTIO_GPU_FILL_CMD(unref);
> +
> +    trace_virtio_gpu_cmd_res_unref(unref.resource_id);
> +
> +    res = virtio_gpu_find_resource(g, unref.resource_id);
> +    CHECK(res, cmd);
> +
> +    result = rutabaga_resource_unref(vr->rutabaga, unref.resource_id);
> +    CHECK(!result, cmd);
> +
> +    if (res->image) {
> +        pixman_image_unref(res->image);
> +    }
> +
> +    QTAILQ_REMOVE(&g->reslist, res, next);
> +    g_free(res);
> +}
> +
> +static void
> +rutabaga_cmd_context_create(VirtIOGPU *g,
> +                            struct virtio_gpu_ctrl_command *cmd)
> +{
> +    int32_t result;
> +    struct virtio_gpu_ctx_create cc;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    VIRTIO_GPU_FILL_CMD(cc);
> +    trace_virtio_gpu_cmd_ctx_create(cc.hdr.ctx_id,
> +                                    cc.debug_name);
> +
> +    result = rutabaga_context_create(vr->rutabaga, cc.hdr.ctx_id,
> +                                     cc.context_init, cc.debug_name, cc.nlen);
> +    CHECK(!result, cmd);
> +}
> +
> +static void
> +rutabaga_cmd_context_destroy(VirtIOGPU *g,
> +                             struct virtio_gpu_ctrl_command *cmd)
> +{
> +    int32_t result;
> +    struct virtio_gpu_ctx_destroy cd;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    VIRTIO_GPU_FILL_CMD(cd);
> +    trace_virtio_gpu_cmd_ctx_destroy(cd.hdr.ctx_id);
> +
> +    result = rutabaga_context_destroy(vr->rutabaga, cd.hdr.ctx_id);
> +    CHECK(!result, cmd);
> +}
> +
> +static void
> +rutabaga_cmd_resource_flush(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd)
> +{
> +    int32_t result, i;
> +    struct virtio_gpu_scanout *scanout = NULL;
> +    struct virtio_gpu_simple_resource *res;
> +    struct rutabaga_transfer transfer = { 0 };
> +    struct iovec transfer_iovec;
> +    struct virtio_gpu_resource_flush rf;
> +    bool found = false;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +    if (vr->headless) {
> +        return;
> +    }
> +
> +    VIRTIO_GPU_FILL_CMD(rf);
> +    trace_virtio_gpu_cmd_res_flush(rf.resource_id,
> +                                   rf.r.width, rf.r.height, rf.r.x, rf.r.y);
> +
> +    res = virtio_gpu_find_resource(g, rf.resource_id);
> +    CHECK(res, cmd);
> +
> +    for (i = 0; i < g->parent_obj.conf.max_outputs; i++) {
> +        scanout = &g->parent_obj.scanout[i];
> +        if (i == res->scanout_bitmask) {
> +            found = true;
> +            break;
> +        }
> +    }
> +
> +    if (!found) {
> +        return;
> +    }
> +
> +    transfer.x = 0;
> +    transfer.y = 0;
> +    transfer.z = 0;
> +    transfer.w = res->width;
> +    transfer.h = res->height;
> +    transfer.d = 1;
> +
> +    transfer_iovec.iov_base = pixman_image_get_data(res->image);
> +    transfer_iovec.iov_len = res->width * res->height * 4;
> +
> +    result = rutabaga_resource_transfer_read(vr->rutabaga, 0,
> +                                             rf.resource_id, &transfer,
> +                                             &transfer_iovec);
> +    CHECK(!result, cmd);
> +    dpy_gfx_update_full(scanout->con);
> +}
> +
> +static void
> +rutabaga_cmd_set_scanout(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd)
> +{
> +    struct virtio_gpu_simple_resource *res;
> +    struct virtio_gpu_scanout *scanout = NULL;
> +    struct virtio_gpu_set_scanout ss;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +    if (vr->headless) {
> +        return;
> +    }
> +
> +    VIRTIO_GPU_FILL_CMD(ss);
> +    trace_virtio_gpu_cmd_set_scanout(ss.scanout_id, ss.resource_id,
> +                                     ss.r.width, ss.r.height, ss.r.x, ss.r.y);
> +
> +    CHECK(ss.scanout_id < VIRTIO_GPU_MAX_SCANOUTS, cmd);
> +    scanout = &g->parent_obj.scanout[ss.scanout_id];
> +
> +    if (ss.resource_id == 0) {

You should disable scanout as virtio-gpu-virgl does.

> +        return;
> +    }
> +
> +    res = virtio_gpu_find_resource(g, ss.resource_id);
> +    CHECK(res, cmd);
> +
> +    if (!res->image) {
> +        pixman_format_code_t pformat;
> +        pformat = virtio_gpu_get_pixman_format(res->format);
> +        CHECK(pformat, cmd);
> +
> +        res->image = pixman_image_create_bits(pformat,
> +                                              res->width,
> +                                              res->height,
> +                                              NULL, 0);
> +        CHECK(res->image, cmd);
> +        pixman_image_ref(res->image);
> +    }
> +
> +    g->parent_obj.enable = 1;
> +
> +    /* realloc the surface ptr */
> +    scanout->ds = qemu_create_displaysurface_pixman(res->image);
> +    dpy_gfx_replace_surface(scanout->con, NULL);
> +    dpy_gfx_replace_surface(scanout->con, scanout->ds);
> +    res->scanout_bitmask = ss.scanout_id;
> +}
> +
> +static void
> +rutabaga_cmd_submit_3d(VirtIOGPU *g,
> +                       struct virtio_gpu_ctrl_command *cmd)
> +{
> +    int32_t result;
> +    struct virtio_gpu_cmd_submit cs;
> +    struct rutabaga_command rutabaga_cmd = { 0 };
> +    g_autofree uint8_t *buf = NULL;
> +    size_t s;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    VIRTIO_GPU_FILL_CMD(cs);
> +    trace_virtio_gpu_cmd_ctx_submit(cs.hdr.ctx_id, cs.size);
> +
> +    buf = g_new0(uint8_t, cs.size);
> +    s = iov_to_buf(cmd->elem.out_sg, cmd->elem.out_num,
> +                   sizeof(cs), buf, cs.size);
> +    CHECK(s == cs.size, cmd);
> +
> +    rutabaga_cmd.ctx_id = cs.hdr.ctx_id;
> +    rutabaga_cmd.cmd = buf;
> +    rutabaga_cmd.cmd_size = cs.size;
> +
> +    result = rutabaga_submit_command(vr->rutabaga, &rutabaga_cmd);
> +    CHECK(!result, cmd);
> +}
> +
> +static void
> +rutabaga_cmd_transfer_to_host_2d(VirtIOGPU *g,
> +                                 struct virtio_gpu_ctrl_command *cmd)
> +{
> +    int32_t result;
> +    struct rutabaga_transfer transfer = { 0 };
> +    struct virtio_gpu_transfer_to_host_2d t2d;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    VIRTIO_GPU_FILL_CMD(t2d);
> +    trace_virtio_gpu_cmd_res_xfer_toh_2d(t2d.resource_id);
> +
> +    transfer.x = t2d.r.x;
> +    transfer.y = t2d.r.y;
> +    transfer.z = 0;
> +    transfer.w = t2d.r.width;
> +    transfer.h = t2d.r.height;
> +    transfer.d = 1;
> +
> +    result = rutabaga_resource_transfer_write(vr->rutabaga, 0, t2d.resource_id,
> +                                              &transfer);
> +    CHECK(!result, cmd);
> +}
> +
> +static void
> +rutabaga_cmd_transfer_to_host_3d(VirtIOGPU *g,
> +                                 struct virtio_gpu_ctrl_command *cmd)
> +{
> +    int32_t result;
> +    struct rutabaga_transfer transfer = { 0 };
> +    struct virtio_gpu_transfer_host_3d t3d;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    VIRTIO_GPU_FILL_CMD(t3d);
> +    trace_virtio_gpu_cmd_res_xfer_toh_3d(t3d.resource_id);
> +
> +    transfer.x = t3d.box.x;
> +    transfer.y = t3d.box.y;
> +    transfer.z = t3d.box.z;
> +    transfer.w = t3d.box.w;
> +    transfer.h = t3d.box.h;
> +    transfer.d = t3d.box.d;
> +    transfer.level = t3d.level;
> +    transfer.stride = t3d.stride;
> +    transfer.layer_stride = t3d.layer_stride;
> +    transfer.offset = t3d.offset;
> +
> +    result = rutabaga_resource_transfer_write(vr->rutabaga, t3d.hdr.ctx_id,
> +                                              t3d.resource_id, &transfer);
> +    CHECK(!result, cmd);
> +}
> +
> +static void
> +rutabaga_cmd_transfer_from_host_3d(VirtIOGPU *g,
> +                                   struct virtio_gpu_ctrl_command *cmd)
> +{
> +    int32_t result;
> +    struct rutabaga_transfer transfer = { 0 };
> +    struct virtio_gpu_transfer_host_3d t3d;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    VIRTIO_GPU_FILL_CMD(t3d);
> +    trace_virtio_gpu_cmd_res_xfer_fromh_3d(t3d.resource_id);
> +
> +    transfer.x = t3d.box.x;
> +    transfer.y = t3d.box.y;
> +    transfer.z = t3d.box.z;
> +    transfer.w = t3d.box.w;
> +    transfer.h = t3d.box.h;
> +    transfer.d = t3d.box.d;
> +    transfer.level = t3d.level;
> +    transfer.stride = t3d.stride;
> +    transfer.layer_stride = t3d.layer_stride;
> +    transfer.offset = t3d.offset;
> +
> +    result = rutabaga_resource_transfer_read(vr->rutabaga, t3d.hdr.ctx_id,
> +                                             t3d.resource_id, &transfer, NULL);
> +    CHECK(!result, cmd);
> +}
> +
> +static void
> +rutabaga_cmd_attach_backing(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd)
> +{
> +    struct rutabaga_iovecs vecs = { 0 };
> +    struct virtio_gpu_simple_resource *res;
> +    struct virtio_gpu_resource_attach_backing att_rb;
> +    int ret;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    VIRTIO_GPU_FILL_CMD(att_rb);
> +    trace_virtio_gpu_cmd_res_back_attach(att_rb.resource_id);
> +
> +    res = virtio_gpu_find_resource(g, att_rb.resource_id);
> +    CHECK(res, cmd);
> +    CHECK(!res->iov, cmd);
> +
> +    ret = virtio_gpu_create_mapping_iov(g, att_rb.nr_entries, sizeof(att_rb),
> +                                        cmd, NULL, &res->iov, &res->iov_cnt);
> +    CHECK(!ret, cmd);
> +
> +    vecs.iovecs = res->iov;
> +    vecs.num_iovecs = res->iov_cnt;
> +
> +    ret = rutabaga_resource_attach_backing(vr->rutabaga, att_rb.resource_id,
> +                                           &vecs);
> +    if (ret != 0) {
> +        virtio_gpu_cleanup_mapping(g, res);
> +    }
> +
> +    CHECK(!ret, cmd);
> +}
> +
> +static void
> +rutabaga_cmd_detach_backing(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd)
> +{
> +    struct virtio_gpu_simple_resource *res;
> +    struct virtio_gpu_resource_detach_backing detach_rb;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    VIRTIO_GPU_FILL_CMD(detach_rb);
> +    trace_virtio_gpu_cmd_res_back_detach(detach_rb.resource_id);
> +
> +    res = virtio_gpu_find_resource(g, detach_rb.resource_id);
> +    CHECK(res, cmd);
> +
> +    rutabaga_resource_detach_backing(vr->rutabaga,
> +                                     detach_rb.resource_id);
> +
> +    virtio_gpu_cleanup_mapping(g, res);
> +}
> +
> +static void
> +rutabaga_cmd_ctx_attach_resource(VirtIOGPU *g,
> +                                 struct virtio_gpu_ctrl_command *cmd)
> +{
> +    int32_t result;
> +    struct virtio_gpu_ctx_resource att_res;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    VIRTIO_GPU_FILL_CMD(att_res);
> +    trace_virtio_gpu_cmd_ctx_res_attach(att_res.hdr.ctx_id,
> +                                        att_res.resource_id);
> +
> +    result = rutabaga_context_attach_resource(vr->rutabaga, att_res.hdr.ctx_id,
> +                                              att_res.resource_id);
> +    CHECK(!result, cmd);
> +}
> +
> +static void
> +rutabaga_cmd_ctx_detach_resource(VirtIOGPU *g,
> +                                 struct virtio_gpu_ctrl_command *cmd)
> +{
> +    int32_t result;
> +    struct virtio_gpu_ctx_resource det_res;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    VIRTIO_GPU_FILL_CMD(det_res);
> +    trace_virtio_gpu_cmd_ctx_res_detach(det_res.hdr.ctx_id,
> +                                        det_res.resource_id);
> +
> +    result = rutabaga_context_detach_resource(vr->rutabaga, det_res.hdr.ctx_id,
> +                                              det_res.resource_id);
> +    CHECK(!result, cmd);
> +}
> +
> +static void
> +rutabaga_cmd_get_capset_info(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd)
> +{
> +    int32_t result;
> +    struct virtio_gpu_get_capset_info info;
> +    struct virtio_gpu_resp_capset_info resp;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    VIRTIO_GPU_FILL_CMD(info);
> +
> +    result = rutabaga_get_capset_info(vr->rutabaga, info.capset_index,
> +                                      &resp.capset_id, &resp.capset_max_version,
> +                                      &resp.capset_max_size);
> +    CHECK(!result, cmd);
> +
> +    resp.hdr.type = VIRTIO_GPU_RESP_OK_CAPSET_INFO;
> +    virtio_gpu_ctrl_response(g, cmd, &resp.hdr, sizeof(resp));
> +}
> +
> +static void
> +rutabaga_cmd_get_capset(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd)
> +{
> +    int32_t result;
> +    struct virtio_gpu_get_capset gc;
> +    struct virtio_gpu_resp_capset *resp;
> +    uint32_t capset_size;
> +    uint32_t current_id;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    VIRTIO_GPU_FILL_CMD(gc);
> +    for (uint32_t i = 0; i < vr->num_capsets; i++) {
> +        CHECK(i < vr->num_capsets, cmd);

This CHECK will not work since you have i < vr->num_capsets as the loop 
condition.

> +        result = rutabaga_get_capset_info(vr->rutabaga, i,
> +                                          &current_id, &capset_size,
> +                                          &capset_size);
> +        CHECK(!result, cmd);
> +
> +        if (current_id == gc.capset_id) {
> +            break;
> +        }
> +    }
> +
> +    resp = g_malloc0(sizeof(*resp) + capset_size);
> +    resp->hdr.type = VIRTIO_GPU_RESP_OK_CAPSET;
> +    rutabaga_get_capset(vr->rutabaga, gc.capset_id, gc.capset_version,
> +                        resp->capset_data, capset_size);
> +
> +    virtio_gpu_ctrl_response(g, cmd, &resp->hdr, sizeof(*resp) + capset_size);
> +    g_free(resp);
> +}
> +
> +static void
> +rutabaga_cmd_resource_create_blob(VirtIOGPU *g,
> +                                  struct virtio_gpu_ctrl_command *cmd)
> +{
> +    int result;
> +    struct rutabaga_iovecs vecs = { 0 };
> +    g_autofree struct virtio_gpu_simple_resource *res = NULL;
> +    struct virtio_gpu_resource_create_blob cblob;
> +    struct rutabaga_create_blob rc_blob = { 0 };
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    VIRTIO_GPU_FILL_CMD(cblob);
> +    trace_virtio_gpu_cmd_res_create_blob(cblob.resource_id, cblob.size);
> +
> +    CHECK(cblob.resource_id != 0, cmd);
> +
> +    res = g_new0(struct virtio_gpu_simple_resource, 1);
> +
> +    res->resource_id = cblob.resource_id;
> +    res->blob_size = cblob.size;
> +
> +    if (cblob.blob_mem != VIRTIO_GPU_BLOB_MEM_HOST3D) {
> +        result = virtio_gpu_create_mapping_iov(g, cblob.nr_entries,
> +                                               sizeof(cblob), cmd, &res->addrs,
> +                                               &res->iov, &res->iov_cnt);
> +        CHECK(!result, cmd);
> +    }
> +
> +    rc_blob.blob_id = cblob.blob_id;
> +    rc_blob.blob_mem = cblob.blob_mem;
> +    rc_blob.blob_flags = cblob.blob_flags;
> +    rc_blob.size = cblob.size;
> +
> +    vecs.iovecs = res->iov;
> +    vecs.num_iovecs = res->iov_cnt;
> +
> +    result = rutabaga_resource_create_blob(vr->rutabaga, cblob.hdr.ctx_id,
> +                                           cblob.resource_id, &rc_blob, &vecs,
> +                                           NULL);
> +
> +    if (result && cblob.blob_mem != VIRTIO_GPU_BLOB_MEM_HOST3D) {
> +        virtio_gpu_cleanup_mapping(g, res);
> +    }
> +
> +    CHECK(!result, cmd);
> +
> +    QTAILQ_INSERT_HEAD(&g->reslist, res, next);
> +    res = NULL;
> +}
> +
> +static void
> +rutabaga_cmd_resource_map_blob(VirtIOGPU *g,
> +                               struct virtio_gpu_ctrl_command *cmd)
> +{
> +    int32_t result;
> +    uint32_t map_info = 0;
> +    uint32_t slot = 0;
> +    struct virtio_gpu_simple_resource *res;
> +    struct rutabaga_mapping mapping = { 0 };
> +    struct virtio_gpu_resource_map_blob mblob;
> +    struct virtio_gpu_resp_map_info resp = { 0 };
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    VIRTIO_GPU_FILL_CMD(mblob);
> +
> +    CHECK(mblob.resource_id != 0, cmd);
> +
> +    res = virtio_gpu_find_resource(g, mblob.resource_id);
> +    CHECK(res, cmd);
> +
> +    result = rutabaga_resource_map_info(vr->rutabaga, mblob.resource_id,
> +                                        &map_info);
> +    CHECK(!result, cmd);
> +
> +    /*
> +     * RUTABAGA_MAP_ACCESS_* flags are not part of the virtio-gpu spec, but do
> +     * exist to potentially allow the hypervisor to restrict write access to
> +     * memory. QEMU does not need to use this functionality at the moment.
> +     */
> +    resp.map_info = map_info & RUTABAGA_MAP_CACHE_MASK;
> +
> +    result = rutabaga_resource_map(vr->rutabaga, mblob.resource_id, &mapping);
> +    CHECK(!result, cmd);
> +
> +    for (slot = 0; slot < MAX_SLOTS; slot++) {
> +        if (vr->memory_regions[slot].used) {
> +            continue;
> +        }
> +
> +        MemoryRegion *mr = &(vr->memory_regions[slot].mr);
> +        memory_region_init_ram_ptr(mr, NULL, "blob", mapping.size,
> +                                   mapping.ptr);
> +        memory_region_add_subregion(&g->parent_obj.hostmem,
> +                                    mblob.offset, mr);
> +        vr->memory_regions[slot].resource_id = mblob.resource_id;
> +        vr->memory_regions[slot].used = 1;
> +        break;
> +    }
> +
> +    if (slot >= MAX_SLOTS) {
> +        result = rutabaga_resource_unmap(vr->rutabaga, mblob.resource_id);
> +        CHECK(!result, cmd);
> +    }
> +
> +    CHECK(slot < MAX_SLOTS, cmd);
> +
> +    resp.hdr.type = VIRTIO_GPU_RESP_OK_MAP_INFO;
> +    virtio_gpu_ctrl_response(g, cmd, &resp.hdr, sizeof(resp));
> +}
> +
> +static void
> +rutabaga_cmd_resource_unmap_blob(VirtIOGPU *g,
> +                                 struct virtio_gpu_ctrl_command *cmd)
> +{
> +    int32_t result;
> +    uint32_t slot = 0;
> +    struct virtio_gpu_simple_resource *res;
> +    struct virtio_gpu_resource_unmap_blob ublob;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    VIRTIO_GPU_FILL_CMD(ublob);
> +
> +    CHECK(ublob.resource_id != 0, cmd);
> +
> +    res = virtio_gpu_find_resource(g, ublob.resource_id);
> +    CHECK(res, cmd);
> +
> +    for (slot = 0; slot < MAX_SLOTS; slot++) {
> +        if (vr->memory_regions[slot].resource_id != ublob.resource_id) {
> +            continue;
> +        }
> +
> +        MemoryRegion *mr = &(vr->memory_regions[slot].mr);
> +        memory_region_del_subregion(&g->parent_obj.hostmem, mr);
> +
> +        vr->memory_regions[slot].resource_id = 0;
> +        vr->memory_regions[slot].used = 0;
> +        break;
> +    }
> +
> +    CHECK(slot < MAX_SLOTS, cmd);
> +    result = rutabaga_resource_unmap(vr->rutabaga, res->resource_id);
> +    CHECK(!result, cmd);
> +}
> +
> +static void
> +virtio_gpu_rutabaga_process_cmd(VirtIOGPU *g,
> +                                struct virtio_gpu_ctrl_command *cmd)
> +{
> +    struct rutabaga_fence fence = { 0 };
> +    int32_t result;
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    VIRTIO_GPU_FILL_CMD(cmd->cmd_hdr);
> +
> +    switch (cmd->cmd_hdr.type) {
> +    case VIRTIO_GPU_CMD_CTX_CREATE:
> +        rutabaga_cmd_context_create(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_CTX_DESTROY:
> +        rutabaga_cmd_context_destroy(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_RESOURCE_CREATE_2D:
> +        rutabaga_cmd_create_resource_2d(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_RESOURCE_CREATE_3D:
> +        rutabaga_cmd_create_resource_3d(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_SUBMIT_3D:
> +        rutabaga_cmd_submit_3d(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_TRANSFER_TO_HOST_2D:
> +        rutabaga_cmd_transfer_to_host_2d(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_TRANSFER_TO_HOST_3D:
> +        rutabaga_cmd_transfer_to_host_3d(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_TRANSFER_FROM_HOST_3D:
> +        rutabaga_cmd_transfer_from_host_3d(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_RESOURCE_ATTACH_BACKING:
> +        rutabaga_cmd_attach_backing(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_RESOURCE_DETACH_BACKING:
> +        rutabaga_cmd_detach_backing(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_SET_SCANOUT:
> +        rutabaga_cmd_set_scanout(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_RESOURCE_FLUSH:
> +        rutabaga_cmd_resource_flush(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_RESOURCE_UNREF:
> +        rutabaga_cmd_resource_unref(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_CTX_ATTACH_RESOURCE:
> +        rutabaga_cmd_ctx_attach_resource(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_CTX_DETACH_RESOURCE:
> +        rutabaga_cmd_ctx_detach_resource(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_GET_CAPSET_INFO:
> +        rutabaga_cmd_get_capset_info(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_GET_CAPSET:
> +        rutabaga_cmd_get_capset(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_GET_DISPLAY_INFO:
> +        virtio_gpu_get_display_info(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_GET_EDID:
> +        virtio_gpu_get_edid(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_RESOURCE_CREATE_BLOB:
> +        rutabaga_cmd_resource_create_blob(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_RESOURCE_MAP_BLOB:
> +        rutabaga_cmd_resource_map_blob(g, cmd);
> +        break;
> +    case VIRTIO_GPU_CMD_RESOURCE_UNMAP_BLOB:
> +        rutabaga_cmd_resource_unmap_blob(g, cmd);
> +        break;
> +    default:
> +        cmd->error = VIRTIO_GPU_RESP_ERR_UNSPEC;
> +        break;
> +    }
> +
> +    if (cmd->finished) {
> +        return;
> +    }
> +    if (cmd->error) {
> +        error_report("%s: ctrl 0x%x, error 0x%x", __func__,
> +                     cmd->cmd_hdr.type, cmd->error);
> +        virtio_gpu_ctrl_response_nodata(g, cmd, cmd->error);
> +        return;
> +    }
> +    if (!(cmd->cmd_hdr.flags & VIRTIO_GPU_FLAG_FENCE)) {
> +        virtio_gpu_ctrl_response_nodata(g, cmd, VIRTIO_GPU_RESP_OK_NODATA);
> +        return;
> +    }
> +
> +    fence.flags = cmd->cmd_hdr.flags;
> +    fence.ctx_id = cmd->cmd_hdr.ctx_id;
> +    fence.fence_id = cmd->cmd_hdr.fence_id;
> +    fence.ring_idx = cmd->cmd_hdr.ring_idx;
> +
> +    trace_virtio_gpu_fence_ctrl(cmd->cmd_hdr.fence_id, cmd->cmd_hdr.type);
> +
> +    result = rutabaga_create_fence(vr->rutabaga, &fence);
> +    CHECK(!result, cmd);
> +}
> +
> +static void
> +virtio_gpu_rutabaga_aio_cb(void *opaque)
> +{
> +    struct rutabaga_aio_data *data = opaque;
> +    VirtIOGPU *g = VIRTIO_GPU(data->vr);
> +    struct rutabaga_fence fence_data = data->fence;
> +    struct virtio_gpu_ctrl_command *cmd, *tmp;
> +
> +    uint32_t signaled_ctx_specific = fence_data.flags &
> +                                     RUTABAGA_FLAG_INFO_RING_IDX;
> +
> +    QTAILQ_FOREACH_SAFE(cmd, &g->fenceq, next, tmp) {
> +        /*
> +         * Due to context specific timelines.
> +         */
> +        uint32_t target_ctx_specific = cmd->cmd_hdr.flags &
> +                                       RUTABAGA_FLAG_INFO_RING_IDX;
> +
> +        if (signaled_ctx_specific != target_ctx_specific) {
> +            continue;
> +        }
> +
> +        if (signaled_ctx_specific &&
> +           (cmd->cmd_hdr.ring_idx != fence_data.ring_idx)) {
> +            continue;
> +        }
> +
> +        if (cmd->cmd_hdr.fence_id > fence_data.fence_id) {
> +            continue;
> +        }
> +
> +        trace_virtio_gpu_fence_resp(cmd->cmd_hdr.fence_id);
> +        virtio_gpu_ctrl_response_nodata(g, cmd, VIRTIO_GPU_RESP_OK_NODATA);
> +        QTAILQ_REMOVE(&g->fenceq, cmd, next);
> +        g_free(cmd);
> +    }
> +
> +    g_free(data);
> +}
> +
> +static void
> +virtio_gpu_rutabaga_fence_cb(uint64_t user_data,
> +                             const struct rutabaga_fence *fence) {
> +    struct rutabaga_aio_data *data;
> +    VirtIOGPU *g = (VirtIOGPU *)user_data;
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    /*
> +     * gfxstream and both cross-domain (and even newer versions virglrenderer:
> +     * see VIRGL_RENDERER_ASYNC_FENCE_CB) like to signal fence completion on
> +     * threads ("callback threads") that are different from the thread that
> +     * processes the command queue ("main thread").
> +     *
> +     * crosvm and other virtio-gpu 1.1 implementations enable callback threads
> +     * via locking.  However, on QEMU a deadlock is observed if
> +     * virtio_gpu_ctrl_response_nodata(..) [used in the fence callback] is used
> +     * from a thread that is not the main thread.
> +     *
> +     * The reason is QEMU's internal locking is designed to work with QEMU
> +     * threads (see rcu_register_thread()) and not generic C/C++/Rust threads.
> +     * For now, we can workaround this by scheduling the return of the
> +     * fence descriptors on the main thread.
> +     */
> +
> +    data = g_new0(struct rutabaga_aio_data, 1);
> +    data->vr = vr;
> +    data->fence = *fence;
> +    aio_bh_schedule_oneshot_full(qemu_get_aio_context(),
> +                                 virtio_gpu_rutabaga_aio_cb,
> +                                 data, "aio");
> +}
> +
> +static void
> +virtio_gpu_rutabaga_debug_cb(uint64_t user_data,
> +                             const struct rutabaga_debug *debug) {
> +
> +    if (debug->debug_type == RUTABAGA_DEBUG_ERROR) {
> +        error_report("%s", debug->message);
> +    } else if (debug->debug_type == RUTABAGA_DEBUG_WARN) {
> +        warn_report("%s", debug->message);
> +    } else if (debug->debug_type == RUTABAGA_DEBUG_INFO) {
> +        info_report("%s", debug->message);
> +    }
> +}
> +
> +static int virtio_gpu_rutabaga_init(VirtIOGPU *g, Error **errp)
> +{
> +    int result;
> +    uint64_t capset_mask;
> +    struct rutabaga_builder builder = { 0 };
> +    char wayland_socket_path[UNIX_PATH_MAX];
> +    struct rutabaga_channel channel = { 0 };
> +    struct rutabaga_channels channels = { 0 };
> +
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +    vr->rutabaga = NULL;
> +
> +    if (!vr->capset_names) {
> +        error_setg(errp, "a capset name from the virtio-gpu spec is required");
> +        return -EINVAL;
> +    }
> +
> +    builder.wsi = RUTABAGA_WSI_SURFACELESS;
> +    /*
> +     * Currently, if WSI is specified, the only valid strings are "surfaceless"
> +     * or "headless".  Surfaceless doesn't create a native window surface, but
> +     * does copy from the render target to the Pixman buffer if a virtio-gpu
> +     * 2D hypercall is issued.  Surfacless is the default.
> +     *
> +     * Headless is like surfaceless, but doesn't copy to the Pixman buffer. The
> +     * use case is automated testing environments where there is no need to view
> +     * results.
> +     *
> +     * In the future, more performant virtio-gpu 2D UI integration may be added.
> +     */
> +    if (vr->wsi) {
> +        if (g_str_equal(vr->wsi, "surfaceless")) {
> +            vr->headless = false;
> +        } else if (g_str_equal(vr->wsi, "headless")) {
> +            vr->headless = true;
> +        } else {
> +            error_setg(errp, "invalid wsi option selected");
> +            return -EINVAL;
> +        }
> +    }
> +
> +    result = rutabaga_calculate_capset_mask(vr->capset_names, &capset_mask);
> +    if (result) {
> +        error_setg(errp, "invalid capset names: %s", vr->capset_names);
> +        return result;
> +    }
> +
> +    builder.fence_cb = virtio_gpu_rutabaga_fence_cb;
> +    builder.debug_cb = virtio_gpu_rutabaga_debug_cb;
> +    builder.capset_mask = capset_mask;
> +    builder.user_data = (uint64_t)g;
> +
> +    /*
> +     * If the user doesn't specify the wayland socket path, we try to infer
> +     * the socket via a process similar to the one used by libwayland.
> +     * libwayland does the following:
> +     *
> +     * 1) If $WAYLAND_DISPLAY is set, attempt to connect to
> +     *    $XDG_RUNTIME_DIR/$WAYLAND_DISPLAY
> +     * 2) Otherwise, attempt to connect to $XDG_RUNTIME_DIR/wayland-0
> +     * 3) Otherwise, don't pass a wayland socket to rutabaga. If a guest
> +     *    wayland proxy is launched, it will fail to work.
> +     */
> +    channel.channel_type = RUTABAGA_CHANNEL_TYPE_WAYLAND;
> +    if (!vr->wayland_socket_path) {
> +        const char *runtime_dir = getenv("XDG_RUNTIME_DIR");
> +        const char *display = getenv("WAYLAND_DISPLAY");
> +        if (!display) {
> +            display = "wayland-0";
> +        }
> +
> +        if (runtime_dir) {
> +            result = snprintf(wayland_socket_path, UNIX_PATH_MAX,
> +                              "%s/%s", runtime_dir, display);
> +            if (result > 0 && result < UNIX_PATH_MAX) {
> +                channel.channel_name = wayland_socket_path;
> +            }

As I said in the last email, I think it's better to make a hard error if 
the user requested RUTABAGA_CAPSET_CROSS_DOMAIN but the default socket 
path does not fit in wayland_socket_path.

> +        }
> +    } else {
> +        channel.channel_name = vr->wayland_socket_path;
> +    }
> +
> +    if ((builder.capset_mask & (1 << RUTABAGA_CAPSET_CROSS_DOMAIN))) {
> +        if (channel.channel_name) {
> +            channels.channels = &channel;
> +            channels.num_channels = 1;
> +            builder.channels = &channels;
> +        }
> +    }
> +
> +    result = rutabaga_init(&builder, &vr->rutabaga);
> +    return result;
> +}
> +
> +static int virtio_gpu_rutabaga_get_num_capsets(VirtIOGPU *g)
> +{
> +    int result;
> +    uint32_t num_capsets;
> +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> +
> +    result = rutabaga_get_num_capsets(vr->rutabaga, &num_capsets);
> +    if (result) {
> +        error_report("Failed to get capsets");
> +        return 0;
> +    }
> +    vr->num_capsets = num_capsets;
> +    return num_capsets;
> +}
> +
> +static void virtio_gpu_rutabaga_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
> +{
> +    VirtIOGPU *g = VIRTIO_GPU(vdev);
> +    struct virtio_gpu_ctrl_command *cmd;
> +
> +    if (!virtio_queue_ready(vq)) {
> +        return;
> +    }
> +
> +    cmd = virtqueue_pop(vq, sizeof(struct virtio_gpu_ctrl_command));
> +    while (cmd) {
> +        cmd->vq = vq;
> +        cmd->error = 0;
> +        cmd->finished = false;
> +        QTAILQ_INSERT_TAIL(&g->cmdq, cmd, next);
> +        cmd = virtqueue_pop(vq, sizeof(struct virtio_gpu_ctrl_command));
> +    }
> +
> +    virtio_gpu_process_cmdq(g);
> +}
> +
> +static void virtio_gpu_rutabaga_realize(DeviceState *qdev, Error **errp)
> +{
> +    int num_capsets;
> +    VirtIOGPUBase *bdev = VIRTIO_GPU_BASE(qdev);
> +    VirtIOGPU *gpudev = VIRTIO_GPU(qdev);
> +
> +#if HOST_BIG_ENDIAN
> +    error_setg(errp, "rutabaga is not supported on bigendian platforms");
> +    return;
> +#endif
> +
> +    int result = virtio_gpu_rutabaga_init(gpudev, errp);
> +    if (result) {
> +        error_setg(errp, "virtio_gpu_rutabaga_init failed");
> +        return;
> +    }
> +
> +    num_capsets = virtio_gpu_rutabaga_get_num_capsets(gpudev);
> +    if (!num_capsets) {
> +        return;
> +    }
> +
> +    bdev->conf.flags |= (1 << VIRTIO_GPU_FLAG_RUTABAGA_ENABLED);
> +    bdev->conf.flags |= (1 << VIRTIO_GPU_FLAG_BLOB_ENABLED);
> +    bdev->conf.flags |= (1 << VIRTIO_GPU_FLAG_CONTEXT_INIT_ENABLED);
> +
> +    bdev->virtio_config.num_capsets = num_capsets;
> +    virtio_gpu_device_realize(qdev, errp);
> +}
> +
> +static Property virtio_gpu_rutabaga_properties[] = {
> +    DEFINE_PROP_STRING("capset_names", VirtIOGPURutabaga, capset_names),
> +    DEFINE_PROP_STRING("wayland_socket_path", VirtIOGPURutabaga,
> +                       wayland_socket_path),
> +    DEFINE_PROP_STRING("wsi", VirtIOGPURutabaga, wsi),
> +    DEFINE_PROP_END_OF_LIST(),
> +};
> +
> +static void virtio_gpu_rutabaga_class_init(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +    VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
> +    VirtIOGPUBaseClass *vbc = VIRTIO_GPU_BASE_CLASS(klass);
> +    VirtIOGPUClass *vgc = VIRTIO_GPU_CLASS(klass);
> +
> +    vbc->gl_flushed = virtio_gpu_rutabaga_gl_flushed;
> +    vgc->handle_ctrl = virtio_gpu_rutabaga_handle_ctrl;
> +    vgc->process_cmd = virtio_gpu_rutabaga_process_cmd;
> +    vgc->update_cursor_data = virtio_gpu_rutabaga_update_cursor;
> +
> +    vdc->realize = virtio_gpu_rutabaga_realize;
> +    device_class_set_props(dc, virtio_gpu_rutabaga_properties);
> +}
> +
> +static const TypeInfo virtio_gpu_rutabaga_info = {
> +    .name = TYPE_VIRTIO_GPU_RUTABAGA,
> +    .parent = TYPE_VIRTIO_GPU,
> +    .instance_size = sizeof(VirtIOGPURutabaga),
> +    .class_init = virtio_gpu_rutabaga_class_init,
> +};
> +module_obj(TYPE_VIRTIO_GPU_RUTABAGA);
> +module_kconfig(VIRTIO_GPU);
> +
> +static void virtio_register_types(void)
> +{
> +    type_register_static(&virtio_gpu_rutabaga_info);
> +}
> +
> +type_init(virtio_register_types)
> +
> +module_dep("hw-display-virtio-gpu");
> diff --git a/hw/display/virtio-vga-rutabaga.c b/hw/display/virtio-vga-rutabaga.c
> new file mode 100644
> index 0000000000..2b2ffed8a6
> --- /dev/null
> +++ b/hw/display/virtio-vga-rutabaga.c
> @@ -0,0 +1,51 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include "qemu/osdep.h"
> +#include "hw/pci/pci.h"
> +#include "hw/qdev-properties.h"
> +#include "hw/virtio/virtio-gpu.h"
> +#include "hw/display/vga.h"
> +#include "qapi/error.h"
> +#include "qemu/module.h"
> +#include "virtio-vga.h"
> +#include "qom/object.h"
> +
> +#define TYPE_VIRTIO_VGA_RUTABAGA "virtio-vga-rutabaga"
> +
> +typedef struct VirtIOVGARutabaga VirtIOVGARutabaga;
> +DECLARE_INSTANCE_CHECKER(VirtIOVGARutabaga, VIRTIO_VGA_RUTABAGA,
> +                         TYPE_VIRTIO_VGA_RUTABAGA)
> +
> +struct VirtIOVGARutabaga {
> +    VirtIOVGABase parent_obj;
> +    VirtIOGPURutabaga vdev;
> +};
> +
> +static void virtio_vga_rutabaga_inst_initfn(Object *obj)
> +{
> +    VirtIOVGARutabaga *dev = VIRTIO_VGA_RUTABAGA(obj);
> +
> +    virtio_instance_init_common(obj, &dev->vdev, sizeof(dev->vdev),
> +                                TYPE_VIRTIO_GPU_RUTABAGA);
> +    VIRTIO_VGA_BASE(dev)->vgpu = VIRTIO_GPU_BASE(&dev->vdev);
> +}
> +
> +static VirtioPCIDeviceTypeInfo virtio_vga_rutabaga_info = {
> +    .generic_name  = TYPE_VIRTIO_VGA_RUTABAGA,
> +    .parent        = TYPE_VIRTIO_VGA_BASE,
> +    .instance_size = sizeof(VirtIOVGARutabaga),
> +    .instance_init = virtio_vga_rutabaga_inst_initfn,
> +};
> +module_obj(TYPE_VIRTIO_VGA_RUTABAGA);
> +module_kconfig(VIRTIO_VGA);
> +
> +static void virtio_vga_register_types(void)
> +{
> +    if (have_vga) {
> +        virtio_pci_types_register(&virtio_vga_rutabaga_info);
> +    }
> +}
> +
> +type_init(virtio_vga_register_types)
> +
> +module_dep("hw-display-virtio-vga");

Gurchetan Singh Aug. 15, 2023, 3:50 p.m. UTC | #3

On Tue, Aug 15, 2023 at 8:07 AM Akihiko Odaki <[e-mail]>
wrote:

> On 2023/08/15 9:35, Gurchetan Singh wrote:
> > This adds initial support for gfxstream and cross-domain.  Both
> > features rely on virtio-gpu blob resources and context types, which
> > are also implemented in this patch.
> >
> > gfxstream has a long and illustrious history in Android graphics
> > paravirtualization.  It has been powering graphics in the Android
> > Studio Emulator for more than a decade, which is the main developer
> > platform.
> >
> > Originally conceived by Jesse Hall, it was first known as "EmuGL" [a].
> > The key design characteristic was a 1:1 threading model and
> > auto-generation, which fit nicely with the OpenGLES spec.  It also
> > allowed easy layering with ANGLE on the host, which provides the GLES
> > implementations on Windows or MacOS enviroments.
> >
> > gfxstream has traditionally been maintained by a single engineer, and
> > between 2015 to 2021, the goldfish throne passed to Frank Yang.
> > Historians often remark this glorious reign ("pax gfxstreama" is the
> > academic term) was comparable to that of Augustus and both Queen
> > Elizabeths.  Just to name a few accomplishments in a resplendent
> > panoply: higher versions of GLES, address space graphics, snapshot
> > support and CTS compliant Vulkan [b].
> >
> > One major drawback was the use of out-of-tree goldfish drivers.
> > Android engineers didn't know much about DRM/KMS and especially TTM so
> > a simple guest to host pipe was conceived.
> >
> > Luckily, virtio-gpu 3D started to emerge in 2016 due to the work of
> > the Mesa/virglrenderer communities.  In 2018, the initial virtio-gpu
> > port of gfxstream was done by Cuttlefish enthusiast Alistair Delva.
> > It was a symbol compatible replacement of virglrenderer [c] and named
> > "AVDVirglrenderer".  This implementation forms the basis of the
> > current gfxstream host implementation still in use today.
> >
> > cross-domain support follows a similar arc.  Originally conceived by
> > Wayland aficionado David Reveman and crosvm enjoyer Zach Reizner in
> > 2018, it initially relied on the downstream "virtio-wl" device.
> >
> > In 2020 and 2021, virtio-gpu was extended to include blob resources
> > and multiple timelines by yours truly, features gfxstream/cross-domain
> > both require to function correctly.
> >
> > Right now, we stand at the precipice of a truly fantastic possibility:
> > the Android Emulator powered by upstream QEMU and upstream Linux
> > kernel.  gfxstream will then be packaged properfully, and app
> > developers can even fix gfxstream bugs on their own if they encounter
> > them.
> >
> > It's been quite the ride, my friends.  Where will gfxstream head next,
> > nobody really knows.  I wouldn't be surprised if it's around for
> > another decade, maintained by a new generation of Android graphics
> > enthusiasts.
> >
> > Technical details:
> >    - Very simple initial display integration: just used Pixman
> >    - Largely, 1:1 mapping of virtio-gpu hypercalls to rutabaga function
> >      calls
> >
> > Next steps for Android VMs:
> >    - The next step would be improving display integration and UI
> interfaces
> >      with the goal of the QEMU upstream graphics being in an emulator
> >      release [d].
> >
> > Next steps for Linux VMs for display virtualization:
> >    - For widespread distribution, someone needs to package Sommelier or
> the
> >      wayland-proxy-virtwl [e] ideally into Debian main. In addition,
> newer
> >      versions of the Linux kernel come with DRM_VIRTIO_GPU_KMS option,
> >      which allows disabling KMS hypercalls.  If anyone cares enough,
> it'll
> >      probably be possible to build a custom VM variant that uses this
> display
> >      virtualization strategy.
> >
> > [a]
> https://android-review.googlesource.com/c/platform/development/+/34470
> > [b]
> https://android-review.googlesource.com/q/topic:%22vulkan-hostconnection-start%22
> > [c]
> https://android-review.googlesource.com/c/device/generic/goldfish-opengl/+/761927
> > [d] https://developer.android.com/studio/releases/emulator
> > [e] https://github.com/talex5/wayland-proxy-virtwl
> >
> > Signed-off-by: Gurchetan Singh <[e-mail]>
> > Tested-by: Alyssa Ross <[e-mail]>
> > ---
> > v1: Incorported various suggestions by Akihiko Odaki and Bernard Berschow
> >      - Removed GET_VIRTIO_GPU_GL / GET_RUTABAGA macros
> >      - Used error_report(..)
> >      - Used g_autofree to fix leaks on error paths
> >      - Removed unnecessary casts
> >      - added virtio-gpu-pci-rutabaga.c + virtio-vga-rutabaga.c files
> >
> > v2: Incorported various suggestions by Akihiko Odaki, Marc-André Lureau
> and
> >      Bernard Berschow:
> >      - Parenthesis in CHECK macro
> >      - CHECK_RESULT(result, ..) --> CHECK(!result, ..)
> >      - delay until g->parent_obj.enable = 1
> >      - Additional cast fixes
> >      - initialize directly in virtio_gpu_rutabaga_realize(..)
> >      - add debug callback to hook into QEMU error's APIs
> >
> > v3: Incorporated feedback from Akihiko Odaki and Alyssa Ross:
> >      - Autodetect Wayland socket when not explicitly specified
> >      - Fix map_blob error paths
> >      - Add comment why we need both `res` and `resource` in create blob
> >      - Cast and whitespace fixes
> >      - Big endian check comes before virtio_gpu_rutabaga_init().
> >      - VirtIOVGARUTABAGA --> VirtIOVGARutabaga
> >
> > v4: Incorporated feedback from Akihiko Odaki and Alyssa Ross:
> >      - Double checked all casts
> >      - Remove unnecessary parenthesis
> >      - Removed `resource` in create_blob
> >      - Added comment about failure case
> >      - Pass user-provided socket as-is
> >      - Use stack variable rather than heap allocation
> >      - Future-proofed map info API to give access flags as well
> >
> > v5: Incorporated feedback from Akihiko Odaki:
> >      - Check (ss.scanout_id < VIRTIO_GPU_MAX_SCANOUTS)
> >      - Simplify num_capsets check
> >      - Call cleanup mapping on error paths
> >      - uint64_t --> void* for rutabaga_map(..)
> >      - Removed unnecessary parenthesis
> >      - Removed unnecessary cast
> >      - #define UNIX_PATH_MAX sizeof((struct sockaddr_un) {}.sun_path)
> >      - Reuse result variable
> >      - Report error when default socket doesn't fit in Wayland socket
> path
> >
> >   hw/display/virtio-gpu-pci-rutabaga.c |   48 ++
> >   hw/display/virtio-gpu-rutabaga.c     | 1114 ++++++++++++++++++++++++++
> >   hw/display/virtio-vga-rutabaga.c     |   51 ++
> >   3 files changed, 1213 insertions(+)
> >   create mode 100644 hw/display/virtio-gpu-pci-rutabaga.c
> >   create mode 100644 hw/display/virtio-gpu-rutabaga.c
> >   create mode 100644 hw/display/virtio-vga-rutabaga.c
> >
> > diff --git a/hw/display/virtio-gpu-pci-rutabaga.c
> b/hw/display/virtio-gpu-pci-rutabaga.c
> > new file mode 100644
> > index 0000000000..c71173d8ca
> > --- /dev/null
> > +++ b/hw/display/virtio-gpu-pci-rutabaga.c
> > @@ -0,0 +1,48 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +
> > +#include "qemu/osdep.h"
> > +#include "qapi/error.h"
> > +#include "qemu/module.h"
> > +#include "hw/pci/pci.h"
> > +#include "hw/qdev-properties.h"
> > +#include "hw/virtio/virtio.h"
> > +#include "hw/virtio/virtio-bus.h"
> > +#include "hw/virtio/virtio-gpu-pci.h"
> > +#include "qom/object.h"
> > +
> > +#define TYPE_VIRTIO_GPU_RUTABAGA_PCI "virtio-gpu-rutabaga-pci"
> > +typedef struct VirtIOGPURutabagaPCI VirtIOGPURutabagaPCI;
> > +DECLARE_INSTANCE_CHECKER(VirtIOGPURutabagaPCI, VIRTIO_GPU_RUTABAGA_PCI,
> > +                         TYPE_VIRTIO_GPU_RUTABAGA_PCI)
> > +
> > +struct VirtIOGPURutabagaPCI {
> > +    VirtIOGPUPCIBase parent_obj;
> > +    VirtIOGPURutabaga vdev;
> > +};
> > +
> > +static void virtio_gpu_rutabaga_initfn(Object *obj)
> > +{
> > +    VirtIOGPURutabagaPCI *dev = VIRTIO_GPU_RUTABAGA_PCI(obj);
> > +
> > +    virtio_instance_init_common(obj, &dev->vdev, sizeof(dev->vdev),
> > +                                TYPE_VIRTIO_GPU_RUTABAGA);
> > +    VIRTIO_GPU_PCI_BASE(obj)->vgpu = VIRTIO_GPU_BASE(&dev->vdev);
> > +}
> > +
> > +static const VirtioPCIDeviceTypeInfo virtio_gpu_rutabaga_pci_info = {
> > +    .generic_name = TYPE_VIRTIO_GPU_RUTABAGA_PCI,
> > +    .parent = TYPE_VIRTIO_GPU_PCI_BASE,
> > +    .instance_size = sizeof(VirtIOGPURutabagaPCI),
> > +    .instance_init = virtio_gpu_rutabaga_initfn,
> > +};
> > +module_obj(TYPE_VIRTIO_GPU_RUTABAGA_PCI);
> > +module_kconfig(VIRTIO_PCI);
> > +
> > +static void virtio_gpu_rutabaga_pci_register_types(void)
> > +{
> > +    virtio_pci_types_register(&virtio_gpu_rutabaga_pci_info);
> > +}
> > +
> > +type_init(virtio_gpu_rutabaga_pci_register_types)
> > +
> > +module_dep("hw-display-virtio-gpu-pci");
> > diff --git a/hw/display/virtio-gpu-rutabaga.c
> b/hw/display/virtio-gpu-rutabaga.c
> > new file mode 100644
> > index 0000000000..3f9f106abc
> > --- /dev/null
> > +++ b/hw/display/virtio-gpu-rutabaga.c
> > @@ -0,0 +1,1114 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +
> > +#include "qemu/osdep.h"
> > +#include "qapi/error.h"
> > +#include "qemu/error-report.h"
> > +#include "qemu/iov.h"
> > +#include "trace.h"
> > +#include "hw/virtio/virtio.h"
> > +#include "hw/virtio/virtio-gpu.h"
> > +#include "hw/virtio/virtio-gpu-pixman.h"
> > +#include "hw/virtio/virtio-iommu.h"
> > +
> > +#include <glib/gmem.h>
> > +#include <rutabaga_gfx/rutabaga_gfx_ffi.h>
> > +
> > +#define CHECK(condition, cmd)
>        \
> > +    do {
>       \
> > +        if (!(condition)) {
>        \
> > +            error_report("CHECK failed in %s() %s:" "%d", __func__,
>        \
> > +                         __FILE__, __LINE__);
>        \
> > +            (cmd)->error = VIRTIO_GPU_RESP_ERR_UNSPEC;
>       \
> > +            return;
>        \
> > +       }
>       \
> > +    } while (0)
> > +
> > +/*
> > + * This is the size of the char array in struct sock_addr_un. No
> Wayland socket
> > + * can be created with a path longer than this, including the null
> terminator.
> > + */
> > +#ifndef UNIX_PATH_MAX
>
> You shouldn't need this ifndef.
>
> > +#define UNIX_PATH_MAX sizeof((struct sockaddr_un) {} .sun_path)
> > +#endif
> > +
> > +struct rutabaga_aio_data {
> > +    struct VirtIOGPURutabaga *vr;
> > +    struct rutabaga_fence fence;
> > +};
> > +
> > +static void
> > +virtio_gpu_rutabaga_update_cursor(VirtIOGPU *g, struct
> virtio_gpu_scanout *s,
> > +                                  uint32_t resource_id)
> > +{
> > +    struct virtio_gpu_simple_resource *res;
> > +    struct rutabaga_transfer transfer = { 0 };
> > +    struct iovec transfer_iovec;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    res = virtio_gpu_find_resource(g, resource_id);
> > +    if (!res) {
> > +        return;
> > +    }
> > +
> > +    if (res->width != s->current_cursor->width ||
> > +        res->height != s->current_cursor->height) {
> > +        return;
> > +    }
> > +
> > +    transfer.x = 0;
> > +    transfer.y = 0;
> > +    transfer.z = 0;
> > +    transfer.w = res->width;
> > +    transfer.h = res->height;
> > +    transfer.d = 1;
> > +
> > +    transfer_iovec.iov_base = s->current_cursor->data;
> > +    transfer_iovec.iov_len = res->width * res->height * 4;
> > +
> > +    rutabaga_resource_transfer_read(vr->rutabaga, 0,
> > +                                    resource_id, &transfer,
> > +                                    &transfer_iovec);
> > +}
> > +
> > +static void
> > +virtio_gpu_rutabaga_gl_flushed(VirtIOGPUBase *b)
> > +{
> > +    VirtIOGPU *g = VIRTIO_GPU(b);
> > +    virtio_gpu_process_cmdq(g);
> > +}
> > +
> > +static void
> > +rutabaga_cmd_create_resource_2d(VirtIOGPU *g,
> > +                                struct virtio_gpu_ctrl_command *cmd)
> > +{
> > +    int32_t result;
> > +    struct rutabaga_create_3d rc_3d = { 0 };
> > +    struct virtio_gpu_simple_resource *res;
> > +    struct virtio_gpu_resource_create_2d c2d;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    VIRTIO_GPU_FILL_CMD(c2d);
> > +    trace_virtio_gpu_cmd_res_create_2d(c2d.resource_id, c2d.format,
> > +                                       c2d.width, c2d.height);
> > +
> > +    rc_3d.target = 2;
> > +    rc_3d.format = c2d.format;
> > +    rc_3d.bind = (1 << 1);
> > +    rc_3d.width = c2d.width;
> > +    rc_3d.height = c2d.height;
> > +    rc_3d.depth = 1;
> > +    rc_3d.array_size = 1;
> > +    rc_3d.last_level = 0;
> > +    rc_3d.nr_samples = 0;
> > +    rc_3d.flags = VIRTIO_GPU_RESOURCE_FLAG_Y_0_TOP;
> > +
> > +    result = rutabaga_resource_create_3d(vr->rutabaga, c2d.resource_id,
> &rc_3d);
> > +    CHECK(!result, cmd);
> > +
> > +    res = g_new0(struct virtio_gpu_simple_resource, 1);
> > +    res->width = c2d.width;
> > +    res->height = c2d.height;
> > +    res->format = c2d.format;
> > +    res->resource_id = c2d.resource_id;
> > +
> > +    QTAILQ_INSERT_HEAD(&g->reslist, res, next);
> > +}
> > +
> > +static void
> > +rutabaga_cmd_create_resource_3d(VirtIOGPU *g,
> > +                                struct virtio_gpu_ctrl_command *cmd)
> > +{
> > +    int32_t result;
> > +    struct rutabaga_create_3d rc_3d = { 0 };
> > +    struct virtio_gpu_simple_resource *res;
> > +    struct virtio_gpu_resource_create_3d c3d;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    VIRTIO_GPU_FILL_CMD(c3d);
> > +
> > +    trace_virtio_gpu_cmd_res_create_3d(c3d.resource_id, c3d.format,
> > +                                       c3d.width, c3d.height,
> c3d.depth);
> > +
> > +    rc_3d.target = c3d.target;
> > +    rc_3d.format = c3d.format;
> > +    rc_3d.bind = c3d.bind;
> > +    rc_3d.width = c3d.width;
> > +    rc_3d.height = c3d.height;
> > +    rc_3d.depth = c3d.depth;
> > +    rc_3d.array_size = c3d.array_size;
> > +    rc_3d.last_level = c3d.last_level;
> > +    rc_3d.nr_samples = c3d.nr_samples;
> > +    rc_3d.flags = c3d.flags;
> > +
> > +    result = rutabaga_resource_create_3d(vr->rutabaga, c3d.resource_id,
> &rc_3d);
> > +    CHECK(!result, cmd);
> > +
> > +    res = g_new0(struct virtio_gpu_simple_resource, 1);
> > +    res->width = c3d.width;
> > +    res->height = c3d.height;
> > +    res->format = c3d.format;
> > +    res->resource_id = c3d.resource_id;
> > +
> > +    QTAILQ_INSERT_HEAD(&g->reslist, res, next);
> > +}
> > +
> > +static void
> > +rutabaga_cmd_resource_unref(VirtIOGPU *g,
> > +                            struct virtio_gpu_ctrl_command *cmd)
> > +{
> > +    int32_t result;
> > +    struct virtio_gpu_simple_resource *res;
> > +    struct virtio_gpu_resource_unref unref;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    VIRTIO_GPU_FILL_CMD(unref);
> > +
> > +    trace_virtio_gpu_cmd_res_unref(unref.resource_id);
> > +
> > +    res = virtio_gpu_find_resource(g, unref.resource_id);
> > +    CHECK(res, cmd);
> > +
> > +    result = rutabaga_resource_unref(vr->rutabaga, unref.resource_id);
> > +    CHECK(!result, cmd);
> > +
> > +    if (res->image) {
> > +        pixman_image_unref(res->image);
> > +    }
> > +
> > +    QTAILQ_REMOVE(&g->reslist, res, next);
> > +    g_free(res);
> > +}
> > +
> > +static void
> > +rutabaga_cmd_context_create(VirtIOGPU *g,
> > +                            struct virtio_gpu_ctrl_command *cmd)
> > +{
> > +    int32_t result;
> > +    struct virtio_gpu_ctx_create cc;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    VIRTIO_GPU_FILL_CMD(cc);
> > +    trace_virtio_gpu_cmd_ctx_create(cc.hdr.ctx_id,
> > +                                    cc.debug_name);
> > +
> > +    result = rutabaga_context_create(vr->rutabaga, cc.hdr.ctx_id,
> > +                                     cc.context_init, cc.debug_name,
> cc.nlen);
> > +    CHECK(!result, cmd);
> > +}
> > +
> > +static void
> > +rutabaga_cmd_context_destroy(VirtIOGPU *g,
> > +                             struct virtio_gpu_ctrl_command *cmd)
> > +{
> > +    int32_t result;
> > +    struct virtio_gpu_ctx_destroy cd;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    VIRTIO_GPU_FILL_CMD(cd);
> > +    trace_virtio_gpu_cmd_ctx_destroy(cd.hdr.ctx_id);
> > +
> > +    result = rutabaga_context_destroy(vr->rutabaga, cd.hdr.ctx_id);
> > +    CHECK(!result, cmd);
> > +}
> > +
> > +static void
> > +rutabaga_cmd_resource_flush(VirtIOGPU *g, struct
> virtio_gpu_ctrl_command *cmd)
> > +{
> > +    int32_t result, i;
> > +    struct virtio_gpu_scanout *scanout = NULL;
> > +    struct virtio_gpu_simple_resource *res;
> > +    struct rutabaga_transfer transfer = { 0 };
> > +    struct iovec transfer_iovec;
> > +    struct virtio_gpu_resource_flush rf;
> > +    bool found = false;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +    if (vr->headless) {
> > +        return;
> > +    }
> > +
> > +    VIRTIO_GPU_FILL_CMD(rf);
> > +    trace_virtio_gpu_cmd_res_flush(rf.resource_id,
> > +                                   rf.r.width, rf.r.height, rf.r.x,
> rf.r.y);
> > +
> > +    res = virtio_gpu_find_resource(g, rf.resource_id);
> > +    CHECK(res, cmd);
> > +
> > +    for (i = 0; i < g->parent_obj.conf.max_outputs; i++) {
> > +        scanout = &g->parent_obj.scanout[i];
> > +        if (i == res->scanout_bitmask) {
> > +            found = true;
> > +            break;
> > +        }
> > +    }
> > +
> > +    if (!found) {
> > +        return;
> > +    }
> > +
> > +    transfer.x = 0;
> > +    transfer.y = 0;
> > +    transfer.z = 0;
> > +    transfer.w = res->width;
> > +    transfer.h = res->height;
> > +    transfer.d = 1;
> > +
> > +    transfer_iovec.iov_base = pixman_image_get_data(res->image);
> > +    transfer_iovec.iov_len = res->width * res->height * 4;
> > +
> > +    result = rutabaga_resource_transfer_read(vr->rutabaga, 0,
> > +                                             rf.resource_id, &transfer,
> > +                                             &transfer_iovec);
> > +    CHECK(!result, cmd);
> > +    dpy_gfx_update_full(scanout->con);
> > +}
> > +
> > +static void
> > +rutabaga_cmd_set_scanout(VirtIOGPU *g, struct virtio_gpu_ctrl_command
> *cmd)
> > +{
> > +    struct virtio_gpu_simple_resource *res;
> > +    struct virtio_gpu_scanout *scanout = NULL;
> > +    struct virtio_gpu_set_scanout ss;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +    if (vr->headless) {
> > +        return;
> > +    }
> > +
> > +    VIRTIO_GPU_FILL_CMD(ss);
> > +    trace_virtio_gpu_cmd_set_scanout(ss.scanout_id, ss.resource_id,
> > +                                     ss.r.width, ss.r.height, ss.r.x,
> ss.r.y);
> > +
> > +    CHECK(ss.scanout_id < VIRTIO_GPU_MAX_SCANOUTS, cmd);
> > +    scanout = &g->parent_obj.scanout[ss.scanout_id];
> > +
> > +    if (ss.resource_id == 0) {
>
> You should disable scanout as virtio-gpu-virgl does.
>
> > +        return;
> > +    }
> > +
> > +    res = virtio_gpu_find_resource(g, ss.resource_id);
> > +    CHECK(res, cmd);
> > +
> > +    if (!res->image) {
> > +        pixman_format_code_t pformat;
> > +        pformat = virtio_gpu_get_pixman_format(res->format);
> > +        CHECK(pformat, cmd);
> > +
> > +        res->image = pixman_image_create_bits(pformat,
> > +                                              res->width,
> > +                                              res->height,
> > +                                              NULL, 0);
> > +        CHECK(res->image, cmd);
> > +        pixman_image_ref(res->image);
> > +    }
> > +
> > +    g->parent_obj.enable = 1;
> > +
> > +    /* realloc the surface ptr */
> > +    scanout->ds = qemu_create_displaysurface_pixman(res->image);
> > +    dpy_gfx_replace_surface(scanout->con, NULL);
> > +    dpy_gfx_replace_surface(scanout->con, scanout->ds);
> > +    res->scanout_bitmask = ss.scanout_id;
> > +}
> > +
> > +static void
> > +rutabaga_cmd_submit_3d(VirtIOGPU *g,
> > +                       struct virtio_gpu_ctrl_command *cmd)
> > +{
> > +    int32_t result;
> > +    struct virtio_gpu_cmd_submit cs;
> > +    struct rutabaga_command rutabaga_cmd = { 0 };
> > +    g_autofree uint8_t *buf = NULL;
> > +    size_t s;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    VIRTIO_GPU_FILL_CMD(cs);
> > +    trace_virtio_gpu_cmd_ctx_submit(cs.hdr.ctx_id, cs.size);
> > +
> > +    buf = g_new0(uint8_t, cs.size);
> > +    s = iov_to_buf(cmd->elem.out_sg, cmd->elem.out_num,
> > +                   sizeof(cs), buf, cs.size);
> > +    CHECK(s == cs.size, cmd);
> > +
> > +    rutabaga_cmd.ctx_id = cs.hdr.ctx_id;
> > +    rutabaga_cmd.cmd = buf;
> > +    rutabaga_cmd.cmd_size = cs.size;
> > +
> > +    result = rutabaga_submit_command(vr->rutabaga, &rutabaga_cmd);
> > +    CHECK(!result, cmd);
> > +}
> > +
> > +static void
> > +rutabaga_cmd_transfer_to_host_2d(VirtIOGPU *g,
> > +                                 struct virtio_gpu_ctrl_command *cmd)
> > +{
> > +    int32_t result;
> > +    struct rutabaga_transfer transfer = { 0 };
> > +    struct virtio_gpu_transfer_to_host_2d t2d;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    VIRTIO_GPU_FILL_CMD(t2d);
> > +    trace_virtio_gpu_cmd_res_xfer_toh_2d(t2d.resource_id);
> > +
> > +    transfer.x = t2d.r.x;
> > +    transfer.y = t2d.r.y;
> > +    transfer.z = 0;
> > +    transfer.w = t2d.r.width;
> > +    transfer.h = t2d.r.height;
> > +    transfer.d = 1;
> > +
> > +    result = rutabaga_resource_transfer_write(vr->rutabaga, 0,
> t2d.resource_id,
> > +                                              &transfer);
> > +    CHECK(!result, cmd);
> > +}
> > +
> > +static void
> > +rutabaga_cmd_transfer_to_host_3d(VirtIOGPU *g,
> > +                                 struct virtio_gpu_ctrl_command *cmd)
> > +{
> > +    int32_t result;
> > +    struct rutabaga_transfer transfer = { 0 };
> > +    struct virtio_gpu_transfer_host_3d t3d;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    VIRTIO_GPU_FILL_CMD(t3d);
> > +    trace_virtio_gpu_cmd_res_xfer_toh_3d(t3d.resource_id);
> > +
> > +    transfer.x = t3d.box.x;
> > +    transfer.y = t3d.box.y;
> > +    transfer.z = t3d.box.z;
> > +    transfer.w = t3d.box.w;
> > +    transfer.h = t3d.box.h;
> > +    transfer.d = t3d.box.d;
> > +    transfer.level = t3d.level;
> > +    transfer.stride = t3d.stride;
> > +    transfer.layer_stride = t3d.layer_stride;
> > +    transfer.offset = t3d.offset;
> > +
> > +    result = rutabaga_resource_transfer_write(vr->rutabaga,
> t3d.hdr.ctx_id,
> > +                                              t3d.resource_id,
> &transfer);
> > +    CHECK(!result, cmd);
> > +}
> > +
> > +static void
> > +rutabaga_cmd_transfer_from_host_3d(VirtIOGPU *g,
> > +                                   struct virtio_gpu_ctrl_command *cmd)
> > +{
> > +    int32_t result;
> > +    struct rutabaga_transfer transfer = { 0 };
> > +    struct virtio_gpu_transfer_host_3d t3d;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    VIRTIO_GPU_FILL_CMD(t3d);
> > +    trace_virtio_gpu_cmd_res_xfer_fromh_3d(t3d.resource_id);
> > +
> > +    transfer.x = t3d.box.x;
> > +    transfer.y = t3d.box.y;
> > +    transfer.z = t3d.box.z;
> > +    transfer.w = t3d.box.w;
> > +    transfer.h = t3d.box.h;
> > +    transfer.d = t3d.box.d;
> > +    transfer.level = t3d.level;
> > +    transfer.stride = t3d.stride;
> > +    transfer.layer_stride = t3d.layer_stride;
> > +    transfer.offset = t3d.offset;
> > +
> > +    result = rutabaga_resource_transfer_read(vr->rutabaga,
> t3d.hdr.ctx_id,
> > +                                             t3d.resource_id,
> &transfer, NULL);
> > +    CHECK(!result, cmd);
> > +}
> > +
> > +static void
> > +rutabaga_cmd_attach_backing(VirtIOGPU *g, struct
> virtio_gpu_ctrl_command *cmd)
> > +{
> > +    struct rutabaga_iovecs vecs = { 0 };
> > +    struct virtio_gpu_simple_resource *res;
> > +    struct virtio_gpu_resource_attach_backing att_rb;
> > +    int ret;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    VIRTIO_GPU_FILL_CMD(att_rb);
> > +    trace_virtio_gpu_cmd_res_back_attach(att_rb.resource_id);
> > +
> > +    res = virtio_gpu_find_resource(g, att_rb.resource_id);
> > +    CHECK(res, cmd);
> > +    CHECK(!res->iov, cmd);
> > +
> > +    ret = virtio_gpu_create_mapping_iov(g, att_rb.nr_entries,
> sizeof(att_rb),
> > +                                        cmd, NULL, &res->iov,
> &res->iov_cnt);
> > +    CHECK(!ret, cmd);
> > +
> > +    vecs.iovecs = res->iov;
> > +    vecs.num_iovecs = res->iov_cnt;
> > +
> > +    ret = rutabaga_resource_attach_backing(vr->rutabaga,
> att_rb.resource_id,
> > +                                           &vecs);
> > +    if (ret != 0) {
> > +        virtio_gpu_cleanup_mapping(g, res);
> > +    }
> > +
> > +    CHECK(!ret, cmd);
> > +}
> > +
> > +static void
> > +rutabaga_cmd_detach_backing(VirtIOGPU *g, struct
> virtio_gpu_ctrl_command *cmd)
> > +{
> > +    struct virtio_gpu_simple_resource *res;
> > +    struct virtio_gpu_resource_detach_backing detach_rb;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    VIRTIO_GPU_FILL_CMD(detach_rb);
> > +    trace_virtio_gpu_cmd_res_back_detach(detach_rb.resource_id);
> > +
> > +    res = virtio_gpu_find_resource(g, detach_rb.resource_id);
> > +    CHECK(res, cmd);
> > +
> > +    rutabaga_resource_detach_backing(vr->rutabaga,
> > +                                     detach_rb.resource_id);
> > +
> > +    virtio_gpu_cleanup_mapping(g, res);
> > +}
> > +
> > +static void
> > +rutabaga_cmd_ctx_attach_resource(VirtIOGPU *g,
> > +                                 struct virtio_gpu_ctrl_command *cmd)
> > +{
> > +    int32_t result;
> > +    struct virtio_gpu_ctx_resource att_res;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    VIRTIO_GPU_FILL_CMD(att_res);
> > +    trace_virtio_gpu_cmd_ctx_res_attach(att_res.hdr.ctx_id,
> > +                                        att_res.resource_id);
> > +
> > +    result = rutabaga_context_attach_resource(vr->rutabaga,
> att_res.hdr.ctx_id,
> > +                                              att_res.resource_id);
> > +    CHECK(!result, cmd);
> > +}
> > +
> > +static void
> > +rutabaga_cmd_ctx_detach_resource(VirtIOGPU *g,
> > +                                 struct virtio_gpu_ctrl_command *cmd)
> > +{
> > +    int32_t result;
> > +    struct virtio_gpu_ctx_resource det_res;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    VIRTIO_GPU_FILL_CMD(det_res);
> > +    trace_virtio_gpu_cmd_ctx_res_detach(det_res.hdr.ctx_id,
> > +                                        det_res.resource_id);
> > +
> > +    result = rutabaga_context_detach_resource(vr->rutabaga,
> det_res.hdr.ctx_id,
> > +                                              det_res.resource_id);
> > +    CHECK(!result, cmd);
> > +}
> > +
> > +static void
> > +rutabaga_cmd_get_capset_info(VirtIOGPU *g, struct
> virtio_gpu_ctrl_command *cmd)
> > +{
> > +    int32_t result;
> > +    struct virtio_gpu_get_capset_info info;
> > +    struct virtio_gpu_resp_capset_info resp;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    VIRTIO_GPU_FILL_CMD(info);
> > +
> > +    result = rutabaga_get_capset_info(vr->rutabaga, info.capset_index,
> > +                                      &resp.capset_id,
> &resp.capset_max_version,
> > +                                      &resp.capset_max_size);
> > +    CHECK(!result, cmd);
> > +
> > +    resp.hdr.type = VIRTIO_GPU_RESP_OK_CAPSET_INFO;
> > +    virtio_gpu_ctrl_response(g, cmd, &resp.hdr, sizeof(resp));
> > +}
> > +
> > +static void
> > +rutabaga_cmd_get_capset(VirtIOGPU *g, struct virtio_gpu_ctrl_command
> *cmd)
> > +{
> > +    int32_t result;
> > +    struct virtio_gpu_get_capset gc;
> > +    struct virtio_gpu_resp_capset *resp;
> > +    uint32_t capset_size;
> > +    uint32_t current_id;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    VIRTIO_GPU_FILL_CMD(gc);
> > +    for (uint32_t i = 0; i < vr->num_capsets; i++) {
> > +        CHECK(i < vr->num_capsets, cmd);
>
> This CHECK will not work since you have i < vr->num_capsets as the loop
> condition.
>
> > +        result = rutabaga_get_capset_info(vr->rutabaga, i,
> > +                                          &current_id, &capset_size,
> > +                                          &capset_size);
> > +        CHECK(!result, cmd);
> > +
> > +        if (current_id == gc.capset_id) {
> > +            break;
> > +        }
> > +    }
> > +
> > +    resp = g_malloc0(sizeof(*resp) + capset_size);
> > +    resp->hdr.type = VIRTIO_GPU_RESP_OK_CAPSET;
> > +    rutabaga_get_capset(vr->rutabaga, gc.capset_id, gc.capset_version,
> > +                        resp->capset_data, capset_size);
> > +
> > +    virtio_gpu_ctrl_response(g, cmd, &resp->hdr, sizeof(*resp) +
> capset_size);
> > +    g_free(resp);
> > +}
> > +
> > +static void
> > +rutabaga_cmd_resource_create_blob(VirtIOGPU *g,
> > +                                  struct virtio_gpu_ctrl_command *cmd)
> > +{
> > +    int result;
> > +    struct rutabaga_iovecs vecs = { 0 };
> > +    g_autofree struct virtio_gpu_simple_resource *res = NULL;
> > +    struct virtio_gpu_resource_create_blob cblob;
> > +    struct rutabaga_create_blob rc_blob = { 0 };
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    VIRTIO_GPU_FILL_CMD(cblob);
> > +    trace_virtio_gpu_cmd_res_create_blob(cblob.resource_id, cblob.size);
> > +
> > +    CHECK(cblob.resource_id != 0, cmd);
> > +
> > +    res = g_new0(struct virtio_gpu_simple_resource, 1);
> > +
> > +    res->resource_id = cblob.resource_id;
> > +    res->blob_size = cblob.size;
> > +
> > +    if (cblob.blob_mem != VIRTIO_GPU_BLOB_MEM_HOST3D) {
> > +        result = virtio_gpu_create_mapping_iov(g, cblob.nr_entries,
> > +                                               sizeof(cblob), cmd,
> &res->addrs,
> > +                                               &res->iov,
> &res->iov_cnt);
> > +        CHECK(!result, cmd);
> > +    }
> > +
> > +    rc_blob.blob_id = cblob.blob_id;
> > +    rc_blob.blob_mem = cblob.blob_mem;
> > +    rc_blob.blob_flags = cblob.blob_flags;
> > +    rc_blob.size = cblob.size;
> > +
> > +    vecs.iovecs = res->iov;
> > +    vecs.num_iovecs = res->iov_cnt;
> > +
> > +    result = rutabaga_resource_create_blob(vr->rutabaga,
> cblob.hdr.ctx_id,
> > +                                           cblob.resource_id, &rc_blob,
> &vecs,
> > +                                           NULL);
> > +
> > +    if (result && cblob.blob_mem != VIRTIO_GPU_BLOB_MEM_HOST3D) {
> > +        virtio_gpu_cleanup_mapping(g, res);
> > +    }
> > +
> > +    CHECK(!result, cmd);
> > +
> > +    QTAILQ_INSERT_HEAD(&g->reslist, res, next);
> > +    res = NULL;
> > +}
> > +
> > +static void
> > +rutabaga_cmd_resource_map_blob(VirtIOGPU *g,
> > +                               struct virtio_gpu_ctrl_command *cmd)
> > +{
> > +    int32_t result;
> > +    uint32_t map_info = 0;
> > +    uint32_t slot = 0;
> > +    struct virtio_gpu_simple_resource *res;
> > +    struct rutabaga_mapping mapping = { 0 };
> > +    struct virtio_gpu_resource_map_blob mblob;
> > +    struct virtio_gpu_resp_map_info resp = { 0 };
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    VIRTIO_GPU_FILL_CMD(mblob);
> > +
> > +    CHECK(mblob.resource_id != 0, cmd);
> > +
> > +    res = virtio_gpu_find_resource(g, mblob.resource_id);
> > +    CHECK(res, cmd);
> > +
> > +    result = rutabaga_resource_map_info(vr->rutabaga, mblob.resource_id,
> > +                                        &map_info);
> > +    CHECK(!result, cmd);
> > +
> > +    /*
> > +     * RUTABAGA_MAP_ACCESS_* flags are not part of the virtio-gpu spec,
> but do
> > +     * exist to potentially allow the hypervisor to restrict write
> access to
> > +     * memory. QEMU does not need to use this functionality at the
> moment.
> > +     */
> > +    resp.map_info = map_info & RUTABAGA_MAP_CACHE_MASK;
> > +
> > +    result = rutabaga_resource_map(vr->rutabaga, mblob.resource_id,
> &mapping);
> > +    CHECK(!result, cmd);
> > +
> > +    for (slot = 0; slot < MAX_SLOTS; slot++) {
> > +        if (vr->memory_regions[slot].used) {
> > +            continue;
> > +        }
> > +
> > +        MemoryRegion *mr = &(vr->memory_regions[slot].mr);
> > +        memory_region_init_ram_ptr(mr, NULL, "blob", mapping.size,
> > +                                   mapping.ptr);
> > +        memory_region_add_subregion(&g->parent_obj.hostmem,
> > +                                    mblob.offset, mr);
> > +        vr->memory_regions[slot].resource_id = mblob.resource_id;
> > +        vr->memory_regions[slot].used = 1;
> > +        break;
> > +    }
> > +
> > +    if (slot >= MAX_SLOTS) {
> > +        result = rutabaga_resource_unmap(vr->rutabaga,
> mblob.resource_id);
> > +        CHECK(!result, cmd);
> > +    }
> > +
> > +    CHECK(slot < MAX_SLOTS, cmd);
> > +
> > +    resp.hdr.type = VIRTIO_GPU_RESP_OK_MAP_INFO;
> > +    virtio_gpu_ctrl_response(g, cmd, &resp.hdr, sizeof(resp));
> > +}
> > +
> > +static void
> > +rutabaga_cmd_resource_unmap_blob(VirtIOGPU *g,
> > +                                 struct virtio_gpu_ctrl_command *cmd)
> > +{
> > +    int32_t result;
> > +    uint32_t slot = 0;
> > +    struct virtio_gpu_simple_resource *res;
> > +    struct virtio_gpu_resource_unmap_blob ublob;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    VIRTIO_GPU_FILL_CMD(ublob);
> > +
> > +    CHECK(ublob.resource_id != 0, cmd);
> > +
> > +    res = virtio_gpu_find_resource(g, ublob.resource_id);
> > +    CHECK(res, cmd);
> > +
> > +    for (slot = 0; slot < MAX_SLOTS; slot++) {
> > +        if (vr->memory_regions[slot].resource_id != ublob.resource_id) {
> > +            continue;
> > +        }
> > +
> > +        MemoryRegion *mr = &(vr->memory_regions[slot].mr);
> > +        memory_region_del_subregion(&g->parent_obj.hostmem, mr);
> > +
> > +        vr->memory_regions[slot].resource_id = 0;
> > +        vr->memory_regions[slot].used = 0;
> > +        break;
> > +    }
> > +
> > +    CHECK(slot < MAX_SLOTS, cmd);
> > +    result = rutabaga_resource_unmap(vr->rutabaga, res->resource_id);
> > +    CHECK(!result, cmd);
> > +}
> > +
> > +static void
> > +virtio_gpu_rutabaga_process_cmd(VirtIOGPU *g,
> > +                                struct virtio_gpu_ctrl_command *cmd)
> > +{
> > +    struct rutabaga_fence fence = { 0 };
> > +    int32_t result;
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    VIRTIO_GPU_FILL_CMD(cmd->cmd_hdr);
> > +
> > +    switch (cmd->cmd_hdr.type) {
> > +    case VIRTIO_GPU_CMD_CTX_CREATE:
> > +        rutabaga_cmd_context_create(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_CTX_DESTROY:
> > +        rutabaga_cmd_context_destroy(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_RESOURCE_CREATE_2D:
> > +        rutabaga_cmd_create_resource_2d(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_RESOURCE_CREATE_3D:
> > +        rutabaga_cmd_create_resource_3d(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_SUBMIT_3D:
> > +        rutabaga_cmd_submit_3d(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_TRANSFER_TO_HOST_2D:
> > +        rutabaga_cmd_transfer_to_host_2d(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_TRANSFER_TO_HOST_3D:
> > +        rutabaga_cmd_transfer_to_host_3d(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_TRANSFER_FROM_HOST_3D:
> > +        rutabaga_cmd_transfer_from_host_3d(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_RESOURCE_ATTACH_BACKING:
> > +        rutabaga_cmd_attach_backing(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_RESOURCE_DETACH_BACKING:
> > +        rutabaga_cmd_detach_backing(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_SET_SCANOUT:
> > +        rutabaga_cmd_set_scanout(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_RESOURCE_FLUSH:
> > +        rutabaga_cmd_resource_flush(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_RESOURCE_UNREF:
> > +        rutabaga_cmd_resource_unref(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_CTX_ATTACH_RESOURCE:
> > +        rutabaga_cmd_ctx_attach_resource(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_CTX_DETACH_RESOURCE:
> > +        rutabaga_cmd_ctx_detach_resource(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_GET_CAPSET_INFO:
> > +        rutabaga_cmd_get_capset_info(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_GET_CAPSET:
> > +        rutabaga_cmd_get_capset(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_GET_DISPLAY_INFO:
> > +        virtio_gpu_get_display_info(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_GET_EDID:
> > +        virtio_gpu_get_edid(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_RESOURCE_CREATE_BLOB:
> > +        rutabaga_cmd_resource_create_blob(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_RESOURCE_MAP_BLOB:
> > +        rutabaga_cmd_resource_map_blob(g, cmd);
> > +        break;
> > +    case VIRTIO_GPU_CMD_RESOURCE_UNMAP_BLOB:
> > +        rutabaga_cmd_resource_unmap_blob(g, cmd);
> > +        break;
> > +    default:
> > +        cmd->error = VIRTIO_GPU_RESP_ERR_UNSPEC;
> > +        break;
> > +    }
> > +
> > +    if (cmd->finished) {
> > +        return;
> > +    }
> > +    if (cmd->error) {
> > +        error_report("%s: ctrl 0x%x, error 0x%x", __func__,
> > +                     cmd->cmd_hdr.type, cmd->error);
> > +        virtio_gpu_ctrl_response_nodata(g, cmd, cmd->error);
> > +        return;
> > +    }
> > +    if (!(cmd->cmd_hdr.flags & VIRTIO_GPU_FLAG_FENCE)) {
> > +        virtio_gpu_ctrl_response_nodata(g, cmd,
> VIRTIO_GPU_RESP_OK_NODATA);
> > +        return;
> > +    }
> > +
> > +    fence.flags = cmd->cmd_hdr.flags;
> > +    fence.ctx_id = cmd->cmd_hdr.ctx_id;
> > +    fence.fence_id = cmd->cmd_hdr.fence_id;
> > +    fence.ring_idx = cmd->cmd_hdr.ring_idx;
> > +
> > +    trace_virtio_gpu_fence_ctrl(cmd->cmd_hdr.fence_id,
> cmd->cmd_hdr.type);
> > +
> > +    result = rutabaga_create_fence(vr->rutabaga, &fence);
> > +    CHECK(!result, cmd);
> > +}
> > +
> > +static void
> > +virtio_gpu_rutabaga_aio_cb(void *opaque)
> > +{
> > +    struct rutabaga_aio_data *data = opaque;
> > +    VirtIOGPU *g = VIRTIO_GPU(data->vr);
> > +    struct rutabaga_fence fence_data = data->fence;
> > +    struct virtio_gpu_ctrl_command *cmd, *tmp;
> > +
> > +    uint32_t signaled_ctx_specific = fence_data.flags &
> > +                                     RUTABAGA_FLAG_INFO_RING_IDX;
> > +
> > +    QTAILQ_FOREACH_SAFE(cmd, &g->fenceq, next, tmp) {
> > +        /*
> > +         * Due to context specific timelines.
> > +         */
> > +        uint32_t target_ctx_specific = cmd->cmd_hdr.flags &
> > +                                       RUTABAGA_FLAG_INFO_RING_IDX;
> > +
> > +        if (signaled_ctx_specific != target_ctx_specific) {
> > +            continue;
> > +        }
> > +
> > +        if (signaled_ctx_specific &&
> > +           (cmd->cmd_hdr.ring_idx != fence_data.ring_idx)) {
> > +            continue;
> > +        }
> > +
> > +        if (cmd->cmd_hdr.fence_id > fence_data.fence_id) {
> > +            continue;
> > +        }
> > +
> > +        trace_virtio_gpu_fence_resp(cmd->cmd_hdr.fence_id);
> > +        virtio_gpu_ctrl_response_nodata(g, cmd,
> VIRTIO_GPU_RESP_OK_NODATA);
> > +        QTAILQ_REMOVE(&g->fenceq, cmd, next);
> > +        g_free(cmd);
> > +    }
> > +
> > +    g_free(data);
> > +}
> > +
> > +static void
> > +virtio_gpu_rutabaga_fence_cb(uint64_t user_data,
> > +                             const struct rutabaga_fence *fence) {
> > +    struct rutabaga_aio_data *data;
> > +    VirtIOGPU *g = (VirtIOGPU *)user_data;
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    /*
> > +     * gfxstream and both cross-domain (and even newer versions
> virglrenderer:
> > +     * see VIRGL_RENDERER_ASYNC_FENCE_CB) like to signal fence
> completion on
> > +     * threads ("callback threads") that are different from the thread
> that
> > +     * processes the command queue ("main thread").
> > +     *
> > +     * crosvm and other virtio-gpu 1.1 implementations enable callback
> threads
> > +     * via locking.  However, on QEMU a deadlock is observed if
> > +     * virtio_gpu_ctrl_response_nodata(..) [used in the fence callback]
> is used
> > +     * from a thread that is not the main thread.
> > +     *
> > +     * The reason is QEMU's internal locking is designed to work with
> QEMU
> > +     * threads (see rcu_register_thread()) and not generic C/C++/Rust
> threads.
> > +     * For now, we can workaround this by scheduling the return of the
> > +     * fence descriptors on the main thread.
> > +     */
> > +
> > +    data = g_new0(struct rutabaga_aio_data, 1);
> > +    data->vr = vr;
> > +    data->fence = *fence;
> > +    aio_bh_schedule_oneshot_full(qemu_get_aio_context(),
> > +                                 virtio_gpu_rutabaga_aio_cb,
> > +                                 data, "aio");
> > +}
> > +
> > +static void
> > +virtio_gpu_rutabaga_debug_cb(uint64_t user_data,
> > +                             const struct rutabaga_debug *debug) {
> > +
> > +    if (debug->debug_type == RUTABAGA_DEBUG_ERROR) {
> > +        error_report("%s", debug->message);
> > +    } else if (debug->debug_type == RUTABAGA_DEBUG_WARN) {
> > +        warn_report("%s", debug->message);
> > +    } else if (debug->debug_type == RUTABAGA_DEBUG_INFO) {
> > +        info_report("%s", debug->message);
> > +    }
> > +}
> > +
> > +static int virtio_gpu_rutabaga_init(VirtIOGPU *g, Error **errp)
> > +{
> > +    int result;
> > +    uint64_t capset_mask;
> > +    struct rutabaga_builder builder = { 0 };
> > +    char wayland_socket_path[UNIX_PATH_MAX];
> > +    struct rutabaga_channel channel = { 0 };
> > +    struct rutabaga_channels channels = { 0 };
> > +
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +    vr->rutabaga = NULL;
> > +
> > +    if (!vr->capset_names) {
> > +        error_setg(errp, "a capset name from the virtio-gpu spec is
> required");
> > +        return -EINVAL;
> > +    }
> > +
> > +    builder.wsi = RUTABAGA_WSI_SURFACELESS;
> > +    /*
> > +     * Currently, if WSI is specified, the only valid strings are
> "surfaceless"
> > +     * or "headless".  Surfaceless doesn't create a native window
> surface, but
> > +     * does copy from the render target to the Pixman buffer if a
> virtio-gpu
> > +     * 2D hypercall is issued.  Surfacless is the default.
> > +     *
> > +     * Headless is like surfaceless, but doesn't copy to the Pixman
> buffer. The
> > +     * use case is automated testing environments where there is no
> need to view
> > +     * results.
> > +     *
> > +     * In the future, more performant virtio-gpu 2D UI integration may
> be added.
> > +     */
> > +    if (vr->wsi) {
> > +        if (g_str_equal(vr->wsi, "surfaceless")) {
> > +            vr->headless = false;
> > +        } else if (g_str_equal(vr->wsi, "headless")) {
> > +            vr->headless = true;
> > +        } else {
> > +            error_setg(errp, "invalid wsi option selected");
> > +            return -EINVAL;
> > +        }
> > +    }
> > +
> > +    result = rutabaga_calculate_capset_mask(vr->capset_names,
> &capset_mask);
> > +    if (result) {
> > +        error_setg(errp, "invalid capset names: %s", vr->capset_names);
> > +        return result;
> > +    }
> > +
> > +    builder.fence_cb = virtio_gpu_rutabaga_fence_cb;
> > +    builder.debug_cb = virtio_gpu_rutabaga_debug_cb;
> > +    builder.capset_mask = capset_mask;
> > +    builder.user_data = (uint64_t)g;
> > +
> > +    /*
> > +     * If the user doesn't specify the wayland socket path, we try to
> infer
> > +     * the socket via a process similar to the one used by libwayland.
> > +     * libwayland does the following:
> > +     *
> > +     * 1) If $WAYLAND_DISPLAY is set, attempt to connect to
> > +     *    $XDG_RUNTIME_DIR/$WAYLAND_DISPLAY
> > +     * 2) Otherwise, attempt to connect to $XDG_RUNTIME_DIR/wayland-0
> > +     * 3) Otherwise, don't pass a wayland socket to rutabaga. If a guest
> > +     *    wayland proxy is launched, it will fail to work.
> > +     */
> > +    channel.channel_type = RUTABAGA_CHANNEL_TYPE_WAYLAND;
> > +    if (!vr->wayland_socket_path) {
> > +        const char *runtime_dir = getenv("XDG_RUNTIME_DIR");
> > +        const char *display = getenv("WAYLAND_DISPLAY");
> > +        if (!display) {
> > +            display = "wayland-0";
> > +        }
> > +
> > +        if (runtime_dir) {
> > +            result = snprintf(wayland_socket_path, UNIX_PATH_MAX,
> > +                              "%s/%s", runtime_dir, display);
> > +            if (result > 0 && result < UNIX_PATH_MAX) {
> > +                channel.channel_name = wayland_socket_path;
> > +            }
>
> As I said in the last email, I think it's better to make a hard error if
> the user requested RUTABAGA_CAPSET_CROSS_DOMAIN but the default socket
> path does not fit in wayland_socket_path.
>

I mentioned this in the cover-letter to v5, but messed up the commit
message of patch 6.  But we do want to be possible to use cross_domain
without wayland for following reason:

"It is possible to use cross-domain without enabling Wayland, for guest
swapchain allocation [a] which often needs special handling.  We might
We want to use this capability on MacOS/Windows in the future without
Wayland, hence we shouldn't have hard errors if the default wayland socket
isn't found.

[a]
https://android.googlesource.com/platform/external/minigbm/+/refs/heads/main/virtgpu_cross_domain.c
"

I'll incorporate your other suggestions in v6 though.




>
> > +        }
> > +    } else {
> > +        channel.channel_name = vr->wayland_socket_path;
> > +    }
> > +
> > +    if ((builder.capset_mask & (1 << RUTABAGA_CAPSET_CROSS_DOMAIN))) {
> > +        if (channel.channel_name) {
> > +            channels.channels = &channel;
> > +            channels.num_channels = 1;
> > +            builder.channels = &channels;
> > +        }
> > +    }
> > +
> > +    result = rutabaga_init(&builder, &vr->rutabaga);
> > +    return result;
> > +}
> > +
> > +static int virtio_gpu_rutabaga_get_num_capsets(VirtIOGPU *g)
> > +{
> > +    int result;
> > +    uint32_t num_capsets;
> > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
> > +
> > +    result = rutabaga_get_num_capsets(vr->rutabaga, &num_capsets);
> > +    if (result) {
> > +        error_report("Failed to get capsets");
> > +        return 0;
> > +    }
> > +    vr->num_capsets = num_capsets;
> > +    return num_capsets;
> > +}
> > +
> > +static void virtio_gpu_rutabaga_handle_ctrl(VirtIODevice *vdev,
> VirtQueue *vq)
> > +{
> > +    VirtIOGPU *g = VIRTIO_GPU(vdev);
> > +    struct virtio_gpu_ctrl_command *cmd;
> > +
> > +    if (!virtio_queue_ready(vq)) {
> > +        return;
> > +    }
> > +
> > +    cmd = virtqueue_pop(vq, sizeof(struct virtio_gpu_ctrl_command));
> > +    while (cmd) {
> > +        cmd->vq = vq;
> > +        cmd->error = 0;
> > +        cmd->finished = false;
> > +        QTAILQ_INSERT_TAIL(&g->cmdq, cmd, next);
> > +        cmd = virtqueue_pop(vq, sizeof(struct virtio_gpu_ctrl_command));
> > +    }
> > +
> > +    virtio_gpu_process_cmdq(g);
> > +}
> > +
> > +static void virtio_gpu_rutabaga_realize(DeviceState *qdev, Error **errp)
> > +{
> > +    int num_capsets;
> > +    VirtIOGPUBase *bdev = VIRTIO_GPU_BASE(qdev);
> > +    VirtIOGPU *gpudev = VIRTIO_GPU(qdev);
> > +
> > +#if HOST_BIG_ENDIAN
> > +    error_setg(errp, "rutabaga is not supported on bigendian
> platforms");
> > +    return;
> > +#endif
> > +
> > +    int result = virtio_gpu_rutabaga_init(gpudev, errp);
> > +    if (result) {
> > +        error_setg(errp, "virtio_gpu_rutabaga_init failed");
> > +        return;
> > +    }
> > +
> > +    num_capsets = virtio_gpu_rutabaga_get_num_capsets(gpudev);
> > +    if (!num_capsets) {
> > +        return;
> > +    }
> > +
> > +    bdev->conf.flags |= (1 << VIRTIO_GPU_FLAG_RUTABAGA_ENABLED);
> > +    bdev->conf.flags |= (1 << VIRTIO_GPU_FLAG_BLOB_ENABLED);
> > +    bdev->conf.flags |= (1 << VIRTIO_GPU_FLAG_CONTEXT_INIT_ENABLED);
> > +
> > +    bdev->virtio_config.num_capsets = num_capsets;
> > +    virtio_gpu_device_realize(qdev, errp);
> > +}
> > +
> > +static Property virtio_gpu_rutabaga_properties[] = {
> > +    DEFINE_PROP_STRING("capset_names", VirtIOGPURutabaga, capset_names),
> > +    DEFINE_PROP_STRING("wayland_socket_path", VirtIOGPURutabaga,
> > +                       wayland_socket_path),
> > +    DEFINE_PROP_STRING("wsi", VirtIOGPURutabaga, wsi),
> > +    DEFINE_PROP_END_OF_LIST(),
> > +};
> > +
> > +static void virtio_gpu_rutabaga_class_init(ObjectClass *klass, void
> *data)
> > +{
> > +    DeviceClass *dc = DEVICE_CLASS(klass);
> > +    VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
> > +    VirtIOGPUBaseClass *vbc = VIRTIO_GPU_BASE_CLASS(klass);
> > +    VirtIOGPUClass *vgc = VIRTIO_GPU_CLASS(klass);
> > +
> > +    vbc->gl_flushed = virtio_gpu_rutabaga_gl_flushed;
> > +    vgc->handle_ctrl = virtio_gpu_rutabaga_handle_ctrl;
> > +    vgc->process_cmd = virtio_gpu_rutabaga_process_cmd;
> > +    vgc->update_cursor_data = virtio_gpu_rutabaga_update_cursor;
> > +
> > +    vdc->realize = virtio_gpu_rutabaga_realize;
> > +    device_class_set_props(dc, virtio_gpu_rutabaga_properties);
> > +}
> > +
> > +static const TypeInfo virtio_gpu_rutabaga_info = {
> > +    .name = TYPE_VIRTIO_GPU_RUTABAGA,
> > +    .parent = TYPE_VIRTIO_GPU,
> > +    .instance_size = sizeof(VirtIOGPURutabaga),
> > +    .class_init = virtio_gpu_rutabaga_class_init,
> > +};
> > +module_obj(TYPE_VIRTIO_GPU_RUTABAGA);
> > +module_kconfig(VIRTIO_GPU);
> > +
> > +static void virtio_register_types(void)
> > +{
> > +    type_register_static(&virtio_gpu_rutabaga_info);
> > +}
> > +
> > +type_init(virtio_register_types)
> > +
> > +module_dep("hw-display-virtio-gpu");
> > diff --git a/hw/display/virtio-vga-rutabaga.c
> b/hw/display/virtio-vga-rutabaga.c
> > new file mode 100644
> > index 0000000000..2b2ffed8a6
> > --- /dev/null
> > +++ b/hw/display/virtio-vga-rutabaga.c
> > @@ -0,0 +1,51 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +
> > +#include "qemu/osdep.h"
> > +#include "hw/pci/pci.h"
> > +#include "hw/qdev-properties.h"
> > +#include "hw/virtio/virtio-gpu.h"
> > +#include "hw/display/vga.h"
> > +#include "qapi/error.h"
> > +#include "qemu/module.h"
> > +#include "virtio-vga.h"
> > +#include "qom/object.h"
> > +
> > +#define TYPE_VIRTIO_VGA_RUTABAGA "virtio-vga-rutabaga"
> > +
> > +typedef struct VirtIOVGARutabaga VirtIOVGARutabaga;
> > +DECLARE_INSTANCE_CHECKER(VirtIOVGARutabaga, VIRTIO_VGA_RUTABAGA,
> > +                         TYPE_VIRTIO_VGA_RUTABAGA)
> > +
> > +struct VirtIOVGARutabaga {
> > +    VirtIOVGABase parent_obj;
> > +    VirtIOGPURutabaga vdev;
> > +};
> > +
> > +static void virtio_vga_rutabaga_inst_initfn(Object *obj)
> > +{
> > +    VirtIOVGARutabaga *dev = VIRTIO_VGA_RUTABAGA(obj);
> > +
> > +    virtio_instance_init_common(obj, &dev->vdev, sizeof(dev->vdev),
> > +                                TYPE_VIRTIO_GPU_RUTABAGA);
> > +    VIRTIO_VGA_BASE(dev)->vgpu = VIRTIO_GPU_BASE(&dev->vdev);
> > +}
> > +
> > +static VirtioPCIDeviceTypeInfo virtio_vga_rutabaga_info = {
> > +    .generic_name  = TYPE_VIRTIO_VGA_RUTABAGA,
> > +    .parent        = TYPE_VIRTIO_VGA_BASE,
> > +    .instance_size = sizeof(VirtIOVGARutabaga),
> > +    .instance_init = virtio_vga_rutabaga_inst_initfn,
> > +};
> > +module_obj(TYPE_VIRTIO_VGA_RUTABAGA);
> > +module_kconfig(VIRTIO_VGA);
> > +
> > +static void virtio_vga_register_types(void)
> > +{
> > +    if (have_vga) {
> > +        virtio_pci_types_register(&virtio_vga_rutabaga_info);
> > +    }
> > +}
> > +
> > +type_init(virtio_vga_register_types)
> > +
> > +module_dep("hw-display-virtio-vga");
>

Akihiko Odaki Aug. 16, 2023, 3:15 p.m. UTC | #4

On 2023/08/16 0:50, Gurchetan Singh wrote:
> 
> 
> On Tue, Aug 15, 2023 at 8:07 AM Akihiko Odaki <[e-mail] 
> <mailto:[e-mail]>> wrote:
> 
>     On 2023/08/15 9:35, Gurchetan Singh wrote:
>      > This adds initial support for gfxstream and cross-domain.  Both
>      > features rely on virtio-gpu blob resources and context types, which
>      > are also implemented in this patch.
>      >
>      > gfxstream has a long and illustrious history in Android graphics
>      > paravirtualization.  It has been powering graphics in the Android
>      > Studio Emulator for more than a decade, which is the main developer
>      > platform.
>      >
>      > Originally conceived by Jesse Hall, it was first known as "EmuGL"
>     [a].
>      > The key design characteristic was a 1:1 threading model and
>      > auto-generation, which fit nicely with the OpenGLES spec.  It also
>      > allowed easy layering with ANGLE on the host, which provides the GLES
>      > implementations on Windows or MacOS enviroments.
>      >
>      > gfxstream has traditionally been maintained by a single engineer, and
>      > between 2015 to 2021, the goldfish throne passed to Frank Yang.
>      > Historians often remark this glorious reign ("pax gfxstreama" is the
>      > academic term) was comparable to that of Augustus and both Queen
>      > Elizabeths.  Just to name a few accomplishments in a resplendent
>      > panoply: higher versions of GLES, address space graphics, snapshot
>      > support and CTS compliant Vulkan [b].
>      >
>      > One major drawback was the use of out-of-tree goldfish drivers.
>      > Android engineers didn't know much about DRM/KMS and especially
>     TTM so
>      > a simple guest to host pipe was conceived.
>      >
>      > Luckily, virtio-gpu 3D started to emerge in 2016 due to the work of
>      > the Mesa/virglrenderer communities.  In 2018, the initial virtio-gpu
>      > port of gfxstream was done by Cuttlefish enthusiast Alistair Delva.
>      > It was a symbol compatible replacement of virglrenderer [c] and named
>      > "AVDVirglrenderer".  This implementation forms the basis of the
>      > current gfxstream host implementation still in use today.
>      >
>      > cross-domain support follows a similar arc.  Originally conceived by
>      > Wayland aficionado David Reveman and crosvm enjoyer Zach Reizner in
>      > 2018, it initially relied on the downstream "virtio-wl" device.
>      >
>      > In 2020 and 2021, virtio-gpu was extended to include blob resources
>      > and multiple timelines by yours truly, features
>     gfxstream/cross-domain
>      > both require to function correctly.
>      >
>      > Right now, we stand at the precipice of a truly fantastic
>     possibility:
>      > the Android Emulator powered by upstream QEMU and upstream Linux
>      > kernel.  gfxstream will then be packaged properfully, and app
>      > developers can even fix gfxstream bugs on their own if they encounter
>      > them.
>      >
>      > It's been quite the ride, my friends.  Where will gfxstream head
>     next,
>      > nobody really knows.  I wouldn't be surprised if it's around for
>      > another decade, maintained by a new generation of Android graphics
>      > enthusiasts.
>      >
>      > Technical details:
>      >    - Very simple initial display integration: just used Pixman
>      >    - Largely, 1:1 mapping of virtio-gpu hypercalls to rutabaga
>     function
>      >      calls
>      >
>      > Next steps for Android VMs:
>      >    - The next step would be improving display integration and UI
>     interfaces
>      >      with the goal of the QEMU upstream graphics being in an emulator
>      >      release [d].
>      >
>      > Next steps for Linux VMs for display virtualization:
>      >    - For widespread distribution, someone needs to package
>     Sommelier or the
>      >      wayland-proxy-virtwl [e] ideally into Debian main. In
>     addition, newer
>      >      versions of the Linux kernel come with DRM_VIRTIO_GPU_KMS
>     option,
>      >      which allows disabling KMS hypercalls.  If anyone cares
>     enough, it'll
>      >      probably be possible to build a custom VM variant that uses
>     this display
>      >      virtualization strategy.
>      >
>      > [a]
>     https://android-review.googlesource.com/c/platform/development/+/34470 <https://android-review.googlesource.com/c/platform/development/+/34470>
>      > [b]
>     https://android-review.googlesource.com/q/topic:%22vulkan-hostconnection-start%22 <https://android-review.googlesource.com/q/topic:%22vulkan-hostconnection-start%22>
>      > [c]
>     https://android-review.googlesource.com/c/device/generic/goldfish-opengl/+/761927 <https://android-review.googlesource.com/c/device/generic/goldfish-opengl/+/761927>
>      > [d] https://developer.android.com/studio/releases/emulator
>     <https://developer.android.com/studio/releases/emulator>
>      > [e] https://github.com/talex5/wayland-proxy-virtwl
>     <https://github.com/talex5/wayland-proxy-virtwl>
>      >
>      > Signed-off-by: Gurchetan Singh <[e-mail]
>     <mailto:[e-mail]>>
>      > Tested-by: Alyssa Ross <[e-mail] <mailto:[e-mail]>>
>      > ---
>      > v1: Incorported various suggestions by Akihiko Odaki and Bernard
>     Berschow
>      >      - Removed GET_VIRTIO_GPU_GL / GET_RUTABAGA macros
>      >      - Used error_report(..)
>      >      - Used g_autofree to fix leaks on error paths
>      >      - Removed unnecessary casts
>      >      - added virtio-gpu-pci-rutabaga.c + virtio-vga-rutabaga.c files
>      >
>      > v2: Incorported various suggestions by Akihiko Odaki, Marc-André
>     Lureau and
>      >      Bernard Berschow:
>      >      - Parenthesis in CHECK macro
>      >      - CHECK_RESULT(result, ..) --> CHECK(!result, ..)
>      >      - delay until g->parent_obj.enable = 1
>      >      - Additional cast fixes
>      >      - initialize directly in virtio_gpu_rutabaga_realize(..)
>      >      - add debug callback to hook into QEMU error's APIs
>      >
>      > v3: Incorporated feedback from Akihiko Odaki and Alyssa Ross:
>      >      - Autodetect Wayland socket when not explicitly specified
>      >      - Fix map_blob error paths
>      >      - Add comment why we need both `res` and `resource` in
>     create blob
>      >      - Cast and whitespace fixes
>      >      - Big endian check comes before virtio_gpu_rutabaga_init().
>      >      - VirtIOVGARUTABAGA --> VirtIOVGARutabaga
>      >
>      > v4: Incorporated feedback from Akihiko Odaki and Alyssa Ross:
>      >      - Double checked all casts
>      >      - Remove unnecessary parenthesis
>      >      - Removed `resource` in create_blob
>      >      - Added comment about failure case
>      >      - Pass user-provided socket as-is
>      >      - Use stack variable rather than heap allocation
>      >      - Future-proofed map info API to give access flags as well
>      >
>      > v5: Incorporated feedback from Akihiko Odaki:
>      >      - Check (ss.scanout_id < VIRTIO_GPU_MAX_SCANOUTS)
>      >      - Simplify num_capsets check
>      >      - Call cleanup mapping on error paths
>      >      - uint64_t --> void* for rutabaga_map(..)
>      >      - Removed unnecessary parenthesis
>      >      - Removed unnecessary cast
>      >      - #define UNIX_PATH_MAX sizeof((struct sockaddr_un) {}.sun_path)
>      >      - Reuse result variable
>      >      - Report error when default socket doesn't fit in Wayland
>     socket path
>      >
>      >   hw/display/virtio-gpu-pci-rutabaga.c |   48 ++
>      >   hw/display/virtio-gpu-rutabaga.c     | 1114
>     ++++++++++++++++++++++++++
>      >   hw/display/virtio-vga-rutabaga.c     |   51 ++
>      >   3 files changed, 1213 insertions(+)
>      >   create mode 100644 hw/display/virtio-gpu-pci-rutabaga.c
>      >   create mode 100644 hw/display/virtio-gpu-rutabaga.c
>      >   create mode 100644 hw/display/virtio-vga-rutabaga.c
>      >
>      > diff --git a/hw/display/virtio-gpu-pci-rutabaga.c
>     b/hw/display/virtio-gpu-pci-rutabaga.c
>      > new file mode 100644
>      > index 0000000000..c71173d8ca
>      > --- /dev/null
>      > +++ b/hw/display/virtio-gpu-pci-rutabaga.c
>      > @@ -0,0 +1,48 @@
>      > +// SPDX-License-Identifier: GPL-2.0
>      > +
>      > +#include "qemu/osdep.h"
>      > +#include "qapi/error.h"
>      > +#include "qemu/module.h"
>      > +#include "hw/pci/pci.h"
>      > +#include "hw/qdev-properties.h"
>      > +#include "hw/virtio/virtio.h"
>      > +#include "hw/virtio/virtio-bus.h"
>      > +#include "hw/virtio/virtio-gpu-pci.h"
>      > +#include "qom/object.h"
>      > +
>      > +#define TYPE_VIRTIO_GPU_RUTABAGA_PCI "virtio-gpu-rutabaga-pci"
>      > +typedef struct VirtIOGPURutabagaPCI VirtIOGPURutabagaPCI;
>      > +DECLARE_INSTANCE_CHECKER(VirtIOGPURutabagaPCI,
>     VIRTIO_GPU_RUTABAGA_PCI,
>      > +                         TYPE_VIRTIO_GPU_RUTABAGA_PCI)
>      > +
>      > +struct VirtIOGPURutabagaPCI {
>      > +    VirtIOGPUPCIBase parent_obj;
>      > +    VirtIOGPURutabaga vdev;
>      > +};
>      > +
>      > +static void virtio_gpu_rutabaga_initfn(Object *obj)
>      > +{
>      > +    VirtIOGPURutabagaPCI *dev = VIRTIO_GPU_RUTABAGA_PCI(obj);
>      > +
>      > +    virtio_instance_init_common(obj, &dev->vdev, sizeof(dev->vdev),
>      > +                                TYPE_VIRTIO_GPU_RUTABAGA);
>      > +    VIRTIO_GPU_PCI_BASE(obj)->vgpu = VIRTIO_GPU_BASE(&dev->vdev);
>      > +}
>      > +
>      > +static const VirtioPCIDeviceTypeInfo
>     virtio_gpu_rutabaga_pci_info = {
>      > +    .generic_name = TYPE_VIRTIO_GPU_RUTABAGA_PCI,
>      > +    .parent = TYPE_VIRTIO_GPU_PCI_BASE,
>      > +    .instance_size = sizeof(VirtIOGPURutabagaPCI),
>      > +    .instance_init = virtio_gpu_rutabaga_initfn,
>      > +};
>      > +module_obj(TYPE_VIRTIO_GPU_RUTABAGA_PCI);
>      > +module_kconfig(VIRTIO_PCI);
>      > +
>      > +static void virtio_gpu_rutabaga_pci_register_types(void)
>      > +{
>      > +    virtio_pci_types_register(&virtio_gpu_rutabaga_pci_info);
>      > +}
>      > +
>      > +type_init(virtio_gpu_rutabaga_pci_register_types)
>      > +
>      > +module_dep("hw-display-virtio-gpu-pci");
>      > diff --git a/hw/display/virtio-gpu-rutabaga.c
>     b/hw/display/virtio-gpu-rutabaga.c
>      > new file mode 100644
>      > index 0000000000..3f9f106abc
>      > --- /dev/null
>      > +++ b/hw/display/virtio-gpu-rutabaga.c
>      > @@ -0,0 +1,1114 @@
>      > +// SPDX-License-Identifier: GPL-2.0
>      > +
>      > +#include "qemu/osdep.h"
>      > +#include "qapi/error.h"
>      > +#include "qemu/error-report.h"
>      > +#include "qemu/iov.h"
>      > +#include "trace.h"
>      > +#include "hw/virtio/virtio.h"
>      > +#include "hw/virtio/virtio-gpu.h"
>      > +#include "hw/virtio/virtio-gpu-pixman.h"
>      > +#include "hw/virtio/virtio-iommu.h"
>      > +
>      > +#include <glib/gmem.h>
>      > +#include <rutabaga_gfx/rutabaga_gfx_ffi.h>
>      > +
>      > +#define CHECK(condition, cmd)                                   
>                   \
>      > +    do {                                                       
>                    \
>      > +        if (!(condition)) {                                     
>                   \
>      > +            error_report("CHECK failed in %s() %s:" "%d",
>     __func__,           \
>      > +                         __FILE__, __LINE__);                   
>                   \
>      > +            (cmd)->error = VIRTIO_GPU_RESP_ERR_UNSPEC;         
>                    \
>      > +            return;                                             
>                   \
>      > +       }                                                       
>                    \
>      > +    } while (0)
>      > +
>      > +/*
>      > + * This is the size of the char array in struct sock_addr_un. No
>     Wayland socket
>      > + * can be created with a path longer than this, including the
>     null terminator.
>      > + */
>      > +#ifndef UNIX_PATH_MAX
> 
>     You shouldn't need this ifndef.
> 
>      > +#define UNIX_PATH_MAX sizeof((struct sockaddr_un) {} .sun_path)
>      > +#endif
>      > +
>      > +struct rutabaga_aio_data {
>      > +    struct VirtIOGPURutabaga *vr;
>      > +    struct rutabaga_fence fence;
>      > +};
>      > +
>      > +static void
>      > +virtio_gpu_rutabaga_update_cursor(VirtIOGPU *g, struct
>     virtio_gpu_scanout *s,
>      > +                                  uint32_t resource_id)
>      > +{
>      > +    struct virtio_gpu_simple_resource *res;
>      > +    struct rutabaga_transfer transfer = { 0 };
>      > +    struct iovec transfer_iovec;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    res = virtio_gpu_find_resource(g, resource_id);
>      > +    if (!res) {
>      > +        return;
>      > +    }
>      > +
>      > +    if (res->width != s->current_cursor->width ||
>      > +        res->height != s->current_cursor->height) {
>      > +        return;
>      > +    }
>      > +
>      > +    transfer.x = 0;
>      > +    transfer.y = 0;
>      > +    transfer.z = 0;
>      > +    transfer.w = res->width;
>      > +    transfer.h = res->height;
>      > +    transfer.d = 1;
>      > +
>      > +    transfer_iovec.iov_base = s->current_cursor->data;
>      > +    transfer_iovec.iov_len = res->width * res->height * 4;
>      > +
>      > +    rutabaga_resource_transfer_read(vr->rutabaga, 0,
>      > +                                    resource_id, &transfer,
>      > +                                    &transfer_iovec);
>      > +}
>      > +
>      > +static void
>      > +virtio_gpu_rutabaga_gl_flushed(VirtIOGPUBase *b)
>      > +{
>      > +    VirtIOGPU *g = VIRTIO_GPU(b);
>      > +    virtio_gpu_process_cmdq(g);
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_create_resource_2d(VirtIOGPU *g,
>      > +                                struct virtio_gpu_ctrl_command *cmd)
>      > +{
>      > +    int32_t result;
>      > +    struct rutabaga_create_3d rc_3d = { 0 };
>      > +    struct virtio_gpu_simple_resource *res;
>      > +    struct virtio_gpu_resource_create_2d c2d;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(c2d);
>      > +    trace_virtio_gpu_cmd_res_create_2d(c2d.resource_id, c2d.format,
>      > +                                       c2d.width, c2d.height);
>      > +
>      > +    rc_3d.target = 2;
>      > +    rc_3d.format = c2d.format;
>      > +    rc_3d.bind = (1 << 1);
>      > +    rc_3d.width = c2d.width;
>      > +    rc_3d.height = c2d.height;
>      > +    rc_3d.depth = 1;
>      > +    rc_3d.array_size = 1;
>      > +    rc_3d.last_level = 0;
>      > +    rc_3d.nr_samples = 0;
>      > +    rc_3d.flags = VIRTIO_GPU_RESOURCE_FLAG_Y_0_TOP;
>      > +
>      > +    result = rutabaga_resource_create_3d(vr->rutabaga,
>     c2d.resource_id, &rc_3d);
>      > +    CHECK(!result, cmd);
>      > +
>      > +    res = g_new0(struct virtio_gpu_simple_resource, 1);
>      > +    res->width = c2d.width;
>      > +    res->height = c2d.height;
>      > +    res->format = c2d.format;
>      > +    res->resource_id = c2d.resource_id;
>      > +
>      > +    QTAILQ_INSERT_HEAD(&g->reslist, res, next);
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_create_resource_3d(VirtIOGPU *g,
>      > +                                struct virtio_gpu_ctrl_command *cmd)
>      > +{
>      > +    int32_t result;
>      > +    struct rutabaga_create_3d rc_3d = { 0 };
>      > +    struct virtio_gpu_simple_resource *res;
>      > +    struct virtio_gpu_resource_create_3d c3d;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(c3d);
>      > +
>      > +    trace_virtio_gpu_cmd_res_create_3d(c3d.resource_id, c3d.format,
>      > +                                       c3d.width, c3d.height,
>     c3d.depth);
>      > +
>      > +    rc_3d.target = c3d.target;
>      > +    rc_3d.format = c3d.format;
>      > +    rc_3d.bind = c3d.bind;
>      > +    rc_3d.width = c3d.width;
>      > +    rc_3d.height = c3d.height;
>      > +    rc_3d.depth = c3d.depth;
>      > +    rc_3d.array_size = c3d.array_size;
>      > +    rc_3d.last_level = c3d.last_level;
>      > +    rc_3d.nr_samples = c3d.nr_samples;
>      > +    rc_3d.flags = c3d.flags;
>      > +
>      > +    result = rutabaga_resource_create_3d(vr->rutabaga,
>     c3d.resource_id, &rc_3d);
>      > +    CHECK(!result, cmd);
>      > +
>      > +    res = g_new0(struct virtio_gpu_simple_resource, 1);
>      > +    res->width = c3d.width;
>      > +    res->height = c3d.height;
>      > +    res->format = c3d.format;
>      > +    res->resource_id = c3d.resource_id;
>      > +
>      > +    QTAILQ_INSERT_HEAD(&g->reslist, res, next);
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_resource_unref(VirtIOGPU *g,
>      > +                            struct virtio_gpu_ctrl_command *cmd)
>      > +{
>      > +    int32_t result;
>      > +    struct virtio_gpu_simple_resource *res;
>      > +    struct virtio_gpu_resource_unref unref;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(unref);
>      > +
>      > +    trace_virtio_gpu_cmd_res_unref(unref.resource_id);
>      > +
>      > +    res = virtio_gpu_find_resource(g, unref.resource_id);
>      > +    CHECK(res, cmd);
>      > +
>      > +    result = rutabaga_resource_unref(vr->rutabaga,
>     unref.resource_id);
>      > +    CHECK(!result, cmd);
>      > +
>      > +    if (res->image) {
>      > +        pixman_image_unref(res->image);
>      > +    }
>      > +
>      > +    QTAILQ_REMOVE(&g->reslist, res, next);
>      > +    g_free(res);
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_context_create(VirtIOGPU *g,
>      > +                            struct virtio_gpu_ctrl_command *cmd)
>      > +{
>      > +    int32_t result;
>      > +    struct virtio_gpu_ctx_create cc;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(cc);
>      > +    trace_virtio_gpu_cmd_ctx_create(cc.hdr.ctx_id,
>      > +                                    cc.debug_name);
>      > +
>      > +    result = rutabaga_context_create(vr->rutabaga, cc.hdr.ctx_id,
>      > +                                     cc.context_init,
>     cc.debug_name, cc.nlen);
>      > +    CHECK(!result, cmd);
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_context_destroy(VirtIOGPU *g,
>      > +                             struct virtio_gpu_ctrl_command *cmd)
>      > +{
>      > +    int32_t result;
>      > +    struct virtio_gpu_ctx_destroy cd;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(cd);
>      > +    trace_virtio_gpu_cmd_ctx_destroy(cd.hdr.ctx_id);
>      > +
>      > +    result = rutabaga_context_destroy(vr->rutabaga, cd.hdr.ctx_id);
>      > +    CHECK(!result, cmd);
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_resource_flush(VirtIOGPU *g, struct
>     virtio_gpu_ctrl_command *cmd)
>      > +{
>      > +    int32_t result, i;
>      > +    struct virtio_gpu_scanout *scanout = NULL;
>      > +    struct virtio_gpu_simple_resource *res;
>      > +    struct rutabaga_transfer transfer = { 0 };
>      > +    struct iovec transfer_iovec;
>      > +    struct virtio_gpu_resource_flush rf;
>      > +    bool found = false;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +    if (vr->headless) {
>      > +        return;
>      > +    }
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(rf);
>      > +    trace_virtio_gpu_cmd_res_flush(rf.resource_id,
>      > +                                   rf.r.width, rf.r.height,
>     rf.r.x, rf.r.y);
>      > +
>      > +    res = virtio_gpu_find_resource(g, rf.resource_id);
>      > +    CHECK(res, cmd);
>      > +
>      > +    for (i = 0; i < g->parent_obj.conf.max_outputs; i++) {
>      > +        scanout = &g->parent_obj.scanout[i];
>      > +        if (i == res->scanout_bitmask) {
>      > +            found = true;
>      > +            break;
>      > +        }
>      > +    }
>      > +
>      > +    if (!found) {
>      > +        return;
>      > +    }
>      > +
>      > +    transfer.x = 0;
>      > +    transfer.y = 0;
>      > +    transfer.z = 0;
>      > +    transfer.w = res->width;
>      > +    transfer.h = res->height;
>      > +    transfer.d = 1;
>      > +
>      > +    transfer_iovec.iov_base = pixman_image_get_data(res->image);
>      > +    transfer_iovec.iov_len = res->width * res->height * 4;
>      > +
>      > +    result = rutabaga_resource_transfer_read(vr->rutabaga, 0,
>      > +                                             rf.resource_id,
>     &transfer,
>      > +                                             &transfer_iovec);
>      > +    CHECK(!result, cmd);
>      > +    dpy_gfx_update_full(scanout->con);
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_set_scanout(VirtIOGPU *g, struct
>     virtio_gpu_ctrl_command *cmd)
>      > +{
>      > +    struct virtio_gpu_simple_resource *res;
>      > +    struct virtio_gpu_scanout *scanout = NULL;
>      > +    struct virtio_gpu_set_scanout ss;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +    if (vr->headless) {
>      > +        return;
>      > +    }
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(ss);
>      > +    trace_virtio_gpu_cmd_set_scanout(ss.scanout_id, ss.resource_id,
>      > +                                     ss.r.width, ss.r.height,
>     ss.r.x, ss.r.y);
>      > +
>      > +    CHECK(ss.scanout_id < VIRTIO_GPU_MAX_SCANOUTS, cmd);
>      > +    scanout = &g->parent_obj.scanout[ss.scanout_id];
>      > +
>      > +    if (ss.resource_id == 0) {
> 
>     You should disable scanout as virtio-gpu-virgl does.
> 
>      > +        return;
>      > +    }
>      > +
>      > +    res = virtio_gpu_find_resource(g, ss.resource_id);
>      > +    CHECK(res, cmd);
>      > +
>      > +    if (!res->image) {
>      > +        pixman_format_code_t pformat;
>      > +        pformat = virtio_gpu_get_pixman_format(res->format);
>      > +        CHECK(pformat, cmd);
>      > +
>      > +        res->image = pixman_image_create_bits(pformat,
>      > +                                              res->width,
>      > +                                              res->height,
>      > +                                              NULL, 0);
>      > +        CHECK(res->image, cmd);
>      > +        pixman_image_ref(res->image);
>      > +    }
>      > +
>      > +    g->parent_obj.enable = 1;
>      > +
>      > +    /* realloc the surface ptr */
>      > +    scanout->ds = qemu_create_displaysurface_pixman(res->image);
>      > +    dpy_gfx_replace_surface(scanout->con, NULL);
>      > +    dpy_gfx_replace_surface(scanout->con, scanout->ds);
>      > +    res->scanout_bitmask = ss.scanout_id;
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_submit_3d(VirtIOGPU *g,
>      > +                       struct virtio_gpu_ctrl_command *cmd)
>      > +{
>      > +    int32_t result;
>      > +    struct virtio_gpu_cmd_submit cs;
>      > +    struct rutabaga_command rutabaga_cmd = { 0 };
>      > +    g_autofree uint8_t *buf = NULL;
>      > +    size_t s;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(cs);
>      > +    trace_virtio_gpu_cmd_ctx_submit(cs.hdr.ctx_id, cs.size);
>      > +
>      > +    buf = g_new0(uint8_t, cs.size);
>      > +    s = iov_to_buf(cmd->elem.out_sg, cmd->elem.out_num,
>      > +                   sizeof(cs), buf, cs.size);
>      > +    CHECK(s == cs.size, cmd);
>      > +
>      > +    rutabaga_cmd.ctx_id = cs.hdr.ctx_id;
>      > +    rutabaga_cmd.cmd = buf;
>      > +    rutabaga_cmd.cmd_size = cs.size;
>      > +
>      > +    result = rutabaga_submit_command(vr->rutabaga, &rutabaga_cmd);
>      > +    CHECK(!result, cmd);
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_transfer_to_host_2d(VirtIOGPU *g,
>      > +                                 struct virtio_gpu_ctrl_command
>     *cmd)
>      > +{
>      > +    int32_t result;
>      > +    struct rutabaga_transfer transfer = { 0 };
>      > +    struct virtio_gpu_transfer_to_host_2d t2d;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(t2d);
>      > +    trace_virtio_gpu_cmd_res_xfer_toh_2d(t2d.resource_id);
>      > +
>      > +    transfer.x = t2d.r.x;
>      > +    transfer.y = t2d.r.y;
>      > +    transfer.z = 0;
>      > +    transfer.w = t2d.r.width;
>      > +    transfer.h = t2d.r.height;
>      > +    transfer.d = 1;
>      > +
>      > +    result = rutabaga_resource_transfer_write(vr->rutabaga, 0,
>     t2d.resource_id,
>      > +                                              &transfer);
>      > +    CHECK(!result, cmd);
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_transfer_to_host_3d(VirtIOGPU *g,
>      > +                                 struct virtio_gpu_ctrl_command
>     *cmd)
>      > +{
>      > +    int32_t result;
>      > +    struct rutabaga_transfer transfer = { 0 };
>      > +    struct virtio_gpu_transfer_host_3d t3d;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(t3d);
>      > +    trace_virtio_gpu_cmd_res_xfer_toh_3d(t3d.resource_id);
>      > +
>      > +    transfer.x = t3d.box.x;
>      > +    transfer.y = t3d.box.y;
>      > +    transfer.z = t3d.box.z;
>      > +    transfer.w = t3d.box.w;
>      > +    transfer.h = t3d.box.h;
>      > +    transfer.d = t3d.box.d;
>      > +    transfer.level = t3d.level;
>      > +    transfer.stride = t3d.stride;
>      > +    transfer.layer_stride = t3d.layer_stride;
>      > +    transfer.offset = t3d.offset;
>      > +
>      > +    result = rutabaga_resource_transfer_write(vr->rutabaga,
>     t3d.hdr.ctx_id,
>      > +                                              t3d.resource_id,
>     &transfer);
>      > +    CHECK(!result, cmd);
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_transfer_from_host_3d(VirtIOGPU *g,
>      > +                                   struct
>     virtio_gpu_ctrl_command *cmd)
>      > +{
>      > +    int32_t result;
>      > +    struct rutabaga_transfer transfer = { 0 };
>      > +    struct virtio_gpu_transfer_host_3d t3d;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(t3d);
>      > +    trace_virtio_gpu_cmd_res_xfer_fromh_3d(t3d.resource_id);
>      > +
>      > +    transfer.x = t3d.box.x;
>      > +    transfer.y = t3d.box.y;
>      > +    transfer.z = t3d.box.z;
>      > +    transfer.w = t3d.box.w;
>      > +    transfer.h = t3d.box.h;
>      > +    transfer.d = t3d.box.d;
>      > +    transfer.level = t3d.level;
>      > +    transfer.stride = t3d.stride;
>      > +    transfer.layer_stride = t3d.layer_stride;
>      > +    transfer.offset = t3d.offset;
>      > +
>      > +    result = rutabaga_resource_transfer_read(vr->rutabaga,
>     t3d.hdr.ctx_id,
>      > +                                             t3d.resource_id,
>     &transfer, NULL);
>      > +    CHECK(!result, cmd);
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_attach_backing(VirtIOGPU *g, struct
>     virtio_gpu_ctrl_command *cmd)
>      > +{
>      > +    struct rutabaga_iovecs vecs = { 0 };
>      > +    struct virtio_gpu_simple_resource *res;
>      > +    struct virtio_gpu_resource_attach_backing att_rb;
>      > +    int ret;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(att_rb);
>      > +    trace_virtio_gpu_cmd_res_back_attach(att_rb.resource_id);
>      > +
>      > +    res = virtio_gpu_find_resource(g, att_rb.resource_id);
>      > +    CHECK(res, cmd);
>      > +    CHECK(!res->iov, cmd);
>      > +
>      > +    ret = virtio_gpu_create_mapping_iov(g, att_rb.nr_entries,
>     sizeof(att_rb),
>      > +                                        cmd, NULL, &res->iov,
>     &res->iov_cnt);
>      > +    CHECK(!ret, cmd);
>      > +
>      > +    vecs.iovecs = res->iov;
>      > +    vecs.num_iovecs = res->iov_cnt;
>      > +
>      > +    ret = rutabaga_resource_attach_backing(vr->rutabaga,
>     att_rb.resource_id,
>      > +                                           &vecs);
>      > +    if (ret != 0) {
>      > +        virtio_gpu_cleanup_mapping(g, res);
>      > +    }
>      > +
>      > +    CHECK(!ret, cmd);
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_detach_backing(VirtIOGPU *g, struct
>     virtio_gpu_ctrl_command *cmd)
>      > +{
>      > +    struct virtio_gpu_simple_resource *res;
>      > +    struct virtio_gpu_resource_detach_backing detach_rb;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(detach_rb);
>      > +    trace_virtio_gpu_cmd_res_back_detach(detach_rb.resource_id);
>      > +
>      > +    res = virtio_gpu_find_resource(g, detach_rb.resource_id);
>      > +    CHECK(res, cmd);
>      > +
>      > +    rutabaga_resource_detach_backing(vr->rutabaga,
>      > +                                     detach_rb.resource_id);
>      > +
>      > +    virtio_gpu_cleanup_mapping(g, res);
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_ctx_attach_resource(VirtIOGPU *g,
>      > +                                 struct virtio_gpu_ctrl_command
>     *cmd)
>      > +{
>      > +    int32_t result;
>      > +    struct virtio_gpu_ctx_resource att_res;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(att_res);
>      > +    trace_virtio_gpu_cmd_ctx_res_attach(att_res.hdr.ctx_id,
>      > +                                        att_res.resource_id);
>      > +
>      > +    result = rutabaga_context_attach_resource(vr->rutabaga,
>     att_res.hdr.ctx_id,
>      > +                                              att_res.resource_id);
>      > +    CHECK(!result, cmd);
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_ctx_detach_resource(VirtIOGPU *g,
>      > +                                 struct virtio_gpu_ctrl_command
>     *cmd)
>      > +{
>      > +    int32_t result;
>      > +    struct virtio_gpu_ctx_resource det_res;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(det_res);
>      > +    trace_virtio_gpu_cmd_ctx_res_detach(det_res.hdr.ctx_id,
>      > +                                        det_res.resource_id);
>      > +
>      > +    result = rutabaga_context_detach_resource(vr->rutabaga,
>     det_res.hdr.ctx_id,
>      > +                                              det_res.resource_id);
>      > +    CHECK(!result, cmd);
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_get_capset_info(VirtIOGPU *g, struct
>     virtio_gpu_ctrl_command *cmd)
>      > +{
>      > +    int32_t result;
>      > +    struct virtio_gpu_get_capset_info info;
>      > +    struct virtio_gpu_resp_capset_info resp;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(info);
>      > +
>      > +    result = rutabaga_get_capset_info(vr->rutabaga,
>     info.capset_index,
>      > +                                      &resp.capset_id,
>     &resp.capset_max_version,
>      > +                                      &resp.capset_max_size);
>      > +    CHECK(!result, cmd);
>      > +
>      > +    resp.hdr.type = VIRTIO_GPU_RESP_OK_CAPSET_INFO;
>      > +    virtio_gpu_ctrl_response(g, cmd, &resp.hdr, sizeof(resp));
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_get_capset(VirtIOGPU *g, struct
>     virtio_gpu_ctrl_command *cmd)
>      > +{
>      > +    int32_t result;
>      > +    struct virtio_gpu_get_capset gc;
>      > +    struct virtio_gpu_resp_capset *resp;
>      > +    uint32_t capset_size;
>      > +    uint32_t current_id;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(gc);
>      > +    for (uint32_t i = 0; i < vr->num_capsets; i++) {
>      > +        CHECK(i < vr->num_capsets, cmd);
> 
>     This CHECK will not work since you have i < vr->num_capsets as the loop
>     condition.
> 
>      > +        result = rutabaga_get_capset_info(vr->rutabaga, i,
>      > +                                          &current_id, &capset_size,
>      > +                                          &capset_size);
>      > +        CHECK(!result, cmd);
>      > +
>      > +        if (current_id == gc.capset_id) {
>      > +            break;
>      > +        }
>      > +    }
>      > +
>      > +    resp = g_malloc0(sizeof(*resp) + capset_size);
>      > +    resp->hdr.type = VIRTIO_GPU_RESP_OK_CAPSET;
>      > +    rutabaga_get_capset(vr->rutabaga, gc.capset_id,
>     gc.capset_version,
>      > +                        resp->capset_data, capset_size);
>      > +
>      > +    virtio_gpu_ctrl_response(g, cmd, &resp->hdr, sizeof(*resp) +
>     capset_size);
>      > +    g_free(resp);
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_resource_create_blob(VirtIOGPU *g,
>      > +                                  struct virtio_gpu_ctrl_command
>     *cmd)
>      > +{
>      > +    int result;
>      > +    struct rutabaga_iovecs vecs = { 0 };
>      > +    g_autofree struct virtio_gpu_simple_resource *res = NULL;
>      > +    struct virtio_gpu_resource_create_blob cblob;
>      > +    struct rutabaga_create_blob rc_blob = { 0 };
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(cblob);
>      > +    trace_virtio_gpu_cmd_res_create_blob(cblob.resource_id,
>     cblob.size);
>      > +
>      > +    CHECK(cblob.resource_id != 0, cmd);
>      > +
>      > +    res = g_new0(struct virtio_gpu_simple_resource, 1);
>      > +
>      > +    res->resource_id = cblob.resource_id;
>      > +    res->blob_size = cblob.size;
>      > +
>      > +    if (cblob.blob_mem != VIRTIO_GPU_BLOB_MEM_HOST3D) {
>      > +        result = virtio_gpu_create_mapping_iov(g, cblob.nr_entries,
>      > +                                               sizeof(cblob),
>     cmd, &res->addrs,
>      > +                                               &res->iov,
>     &res->iov_cnt);
>      > +        CHECK(!result, cmd);
>      > +    }
>      > +
>      > +    rc_blob.blob_id = cblob.blob_id;
>      > +    rc_blob.blob_mem = cblob.blob_mem;
>      > +    rc_blob.blob_flags = cblob.blob_flags;
>      > +    rc_blob.size = cblob.size;
>      > +
>      > +    vecs.iovecs = res->iov;
>      > +    vecs.num_iovecs = res->iov_cnt;
>      > +
>      > +    result = rutabaga_resource_create_blob(vr->rutabaga,
>     cblob.hdr.ctx_id,
>      > +                                           cblob.resource_id,
>     &rc_blob, &vecs,
>      > +                                           NULL);
>      > +
>      > +    if (result && cblob.blob_mem != VIRTIO_GPU_BLOB_MEM_HOST3D) {
>      > +        virtio_gpu_cleanup_mapping(g, res);
>      > +    }
>      > +
>      > +    CHECK(!result, cmd);
>      > +
>      > +    QTAILQ_INSERT_HEAD(&g->reslist, res, next);
>      > +    res = NULL;
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_resource_map_blob(VirtIOGPU *g,
>      > +                               struct virtio_gpu_ctrl_command *cmd)
>      > +{
>      > +    int32_t result;
>      > +    uint32_t map_info = 0;
>      > +    uint32_t slot = 0;
>      > +    struct virtio_gpu_simple_resource *res;
>      > +    struct rutabaga_mapping mapping = { 0 };
>      > +    struct virtio_gpu_resource_map_blob mblob;
>      > +    struct virtio_gpu_resp_map_info resp = { 0 };
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(mblob);
>      > +
>      > +    CHECK(mblob.resource_id != 0, cmd);
>      > +
>      > +    res = virtio_gpu_find_resource(g, mblob.resource_id);
>      > +    CHECK(res, cmd);
>      > +
>      > +    result = rutabaga_resource_map_info(vr->rutabaga,
>     mblob.resource_id,
>      > +                                        &map_info);
>      > +    CHECK(!result, cmd);
>      > +
>      > +    /*
>      > +     * RUTABAGA_MAP_ACCESS_* flags are not part of the
>     virtio-gpu spec, but do
>      > +     * exist to potentially allow the hypervisor to restrict
>     write access to
>      > +     * memory. QEMU does not need to use this functionality at
>     the moment.
>      > +     */
>      > +    resp.map_info = map_info & RUTABAGA_MAP_CACHE_MASK;
>      > +
>      > +    result = rutabaga_resource_map(vr->rutabaga,
>     mblob.resource_id, &mapping);
>      > +    CHECK(!result, cmd);
>      > +
>      > +    for (slot = 0; slot < MAX_SLOTS; slot++) {
>      > +        if (vr->memory_regions[slot].used) {
>      > +            continue;
>      > +        }
>      > +
>      > +        MemoryRegion *mr = &(vr->memory_regions[slot].mr);
>      > +        memory_region_init_ram_ptr(mr, NULL, "blob", mapping.size,
>      > +                                   mapping.ptr);
>      > +        memory_region_add_subregion(&g->parent_obj.hostmem,
>      > +                                    mblob.offset, mr);
>      > +        vr->memory_regions[slot].resource_id = mblob.resource_id;
>      > +        vr->memory_regions[slot].used = 1;
>      > +        break;
>      > +    }
>      > +
>      > +    if (slot >= MAX_SLOTS) {
>      > +        result = rutabaga_resource_unmap(vr->rutabaga,
>     mblob.resource_id);
>      > +        CHECK(!result, cmd);
>      > +    }
>      > +
>      > +    CHECK(slot < MAX_SLOTS, cmd);
>      > +
>      > +    resp.hdr.type = VIRTIO_GPU_RESP_OK_MAP_INFO;
>      > +    virtio_gpu_ctrl_response(g, cmd, &resp.hdr, sizeof(resp));
>      > +}
>      > +
>      > +static void
>      > +rutabaga_cmd_resource_unmap_blob(VirtIOGPU *g,
>      > +                                 struct virtio_gpu_ctrl_command
>     *cmd)
>      > +{
>      > +    int32_t result;
>      > +    uint32_t slot = 0;
>      > +    struct virtio_gpu_simple_resource *res;
>      > +    struct virtio_gpu_resource_unmap_blob ublob;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(ublob);
>      > +
>      > +    CHECK(ublob.resource_id != 0, cmd);
>      > +
>      > +    res = virtio_gpu_find_resource(g, ublob.resource_id);
>      > +    CHECK(res, cmd);
>      > +
>      > +    for (slot = 0; slot < MAX_SLOTS; slot++) {
>      > +        if (vr->memory_regions[slot].resource_id !=
>     ublob.resource_id) {
>      > +            continue;
>      > +        }
>      > +
>      > +        MemoryRegion *mr = &(vr->memory_regions[slot].mr);
>      > +        memory_region_del_subregion(&g->parent_obj.hostmem, mr);
>      > +
>      > +        vr->memory_regions[slot].resource_id = 0;
>      > +        vr->memory_regions[slot].used = 0;
>      > +        break;
>      > +    }
>      > +
>      > +    CHECK(slot < MAX_SLOTS, cmd);
>      > +    result = rutabaga_resource_unmap(vr->rutabaga,
>     res->resource_id);
>      > +    CHECK(!result, cmd);
>      > +}
>      > +
>      > +static void
>      > +virtio_gpu_rutabaga_process_cmd(VirtIOGPU *g,
>      > +                                struct virtio_gpu_ctrl_command *cmd)
>      > +{
>      > +    struct rutabaga_fence fence = { 0 };
>      > +    int32_t result;
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    VIRTIO_GPU_FILL_CMD(cmd->cmd_hdr);
>      > +
>      > +    switch (cmd->cmd_hdr.type) {
>      > +    case VIRTIO_GPU_CMD_CTX_CREATE:
>      > +        rutabaga_cmd_context_create(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_CTX_DESTROY:
>      > +        rutabaga_cmd_context_destroy(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_RESOURCE_CREATE_2D:
>      > +        rutabaga_cmd_create_resource_2d(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_RESOURCE_CREATE_3D:
>      > +        rutabaga_cmd_create_resource_3d(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_SUBMIT_3D:
>      > +        rutabaga_cmd_submit_3d(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_TRANSFER_TO_HOST_2D:
>      > +        rutabaga_cmd_transfer_to_host_2d(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_TRANSFER_TO_HOST_3D:
>      > +        rutabaga_cmd_transfer_to_host_3d(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_TRANSFER_FROM_HOST_3D:
>      > +        rutabaga_cmd_transfer_from_host_3d(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_RESOURCE_ATTACH_BACKING:
>      > +        rutabaga_cmd_attach_backing(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_RESOURCE_DETACH_BACKING:
>      > +        rutabaga_cmd_detach_backing(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_SET_SCANOUT:
>      > +        rutabaga_cmd_set_scanout(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_RESOURCE_FLUSH:
>      > +        rutabaga_cmd_resource_flush(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_RESOURCE_UNREF:
>      > +        rutabaga_cmd_resource_unref(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_CTX_ATTACH_RESOURCE:
>      > +        rutabaga_cmd_ctx_attach_resource(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_CTX_DETACH_RESOURCE:
>      > +        rutabaga_cmd_ctx_detach_resource(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_GET_CAPSET_INFO:
>      > +        rutabaga_cmd_get_capset_info(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_GET_CAPSET:
>      > +        rutabaga_cmd_get_capset(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_GET_DISPLAY_INFO:
>      > +        virtio_gpu_get_display_info(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_GET_EDID:
>      > +        virtio_gpu_get_edid(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_RESOURCE_CREATE_BLOB:
>      > +        rutabaga_cmd_resource_create_blob(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_RESOURCE_MAP_BLOB:
>      > +        rutabaga_cmd_resource_map_blob(g, cmd);
>      > +        break;
>      > +    case VIRTIO_GPU_CMD_RESOURCE_UNMAP_BLOB:
>      > +        rutabaga_cmd_resource_unmap_blob(g, cmd);
>      > +        break;
>      > +    default:
>      > +        cmd->error = VIRTIO_GPU_RESP_ERR_UNSPEC;
>      > +        break;
>      > +    }
>      > +
>      > +    if (cmd->finished) {
>      > +        return;
>      > +    }
>      > +    if (cmd->error) {
>      > +        error_report("%s: ctrl 0x%x, error 0x%x", __func__,
>      > +                     cmd->cmd_hdr.type, cmd->error);
>      > +        virtio_gpu_ctrl_response_nodata(g, cmd, cmd->error);
>      > +        return;
>      > +    }
>      > +    if (!(cmd->cmd_hdr.flags & VIRTIO_GPU_FLAG_FENCE)) {
>      > +        virtio_gpu_ctrl_response_nodata(g, cmd,
>     VIRTIO_GPU_RESP_OK_NODATA);
>      > +        return;
>      > +    }
>      > +
>      > +    fence.flags = cmd->cmd_hdr.flags;
>      > +    fence.ctx_id = cmd->cmd_hdr.ctx_id;
>      > +    fence.fence_id = cmd->cmd_hdr.fence_id;
>      > +    fence.ring_idx = cmd->cmd_hdr.ring_idx;
>      > +
>      > +    trace_virtio_gpu_fence_ctrl(cmd->cmd_hdr.fence_id,
>     cmd->cmd_hdr.type);
>      > +
>      > +    result = rutabaga_create_fence(vr->rutabaga, &fence);
>      > +    CHECK(!result, cmd);
>      > +}
>      > +
>      > +static void
>      > +virtio_gpu_rutabaga_aio_cb(void *opaque)
>      > +{
>      > +    struct rutabaga_aio_data *data = opaque;
>      > +    VirtIOGPU *g = VIRTIO_GPU(data->vr);
>      > +    struct rutabaga_fence fence_data = data->fence;
>      > +    struct virtio_gpu_ctrl_command *cmd, *tmp;
>      > +
>      > +    uint32_t signaled_ctx_specific = fence_data.flags &
>      > +                                     RUTABAGA_FLAG_INFO_RING_IDX;
>      > +
>      > +    QTAILQ_FOREACH_SAFE(cmd, &g->fenceq, next, tmp) {
>      > +        /*
>      > +         * Due to context specific timelines.
>      > +         */
>      > +        uint32_t target_ctx_specific = cmd->cmd_hdr.flags &
>      > +                                       RUTABAGA_FLAG_INFO_RING_IDX;
>      > +
>      > +        if (signaled_ctx_specific != target_ctx_specific) {
>      > +            continue;
>      > +        }
>      > +
>      > +        if (signaled_ctx_specific &&
>      > +           (cmd->cmd_hdr.ring_idx != fence_data.ring_idx)) {
>      > +            continue;
>      > +        }
>      > +
>      > +        if (cmd->cmd_hdr.fence_id > fence_data.fence_id) {
>      > +            continue;
>      > +        }
>      > +
>      > +        trace_virtio_gpu_fence_resp(cmd->cmd_hdr.fence_id);
>      > +        virtio_gpu_ctrl_response_nodata(g, cmd,
>     VIRTIO_GPU_RESP_OK_NODATA);
>      > +        QTAILQ_REMOVE(&g->fenceq, cmd, next);
>      > +        g_free(cmd);
>      > +    }
>      > +
>      > +    g_free(data);
>      > +}
>      > +
>      > +static void
>      > +virtio_gpu_rutabaga_fence_cb(uint64_t user_data,
>      > +                             const struct rutabaga_fence *fence) {
>      > +    struct rutabaga_aio_data *data;
>      > +    VirtIOGPU *g = (VirtIOGPU *)user_data;
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +
>      > +    /*
>      > +     * gfxstream and both cross-domain (and even newer versions
>     virglrenderer:
>      > +     * see VIRGL_RENDERER_ASYNC_FENCE_CB) like to signal fence
>     completion on
>      > +     * threads ("callback threads") that are different from the
>     thread that
>      > +     * processes the command queue ("main thread").
>      > +     *
>      > +     * crosvm and other virtio-gpu 1.1 implementations enable
>     callback threads
>      > +     * via locking.  However, on QEMU a deadlock is observed if
>      > +     * virtio_gpu_ctrl_response_nodata(..) [used in the fence
>     callback] is used
>      > +     * from a thread that is not the main thread.
>      > +     *
>      > +     * The reason is QEMU's internal locking is designed to work
>     with QEMU
>      > +     * threads (see rcu_register_thread()) and not generic
>     C/C++/Rust threads.
>      > +     * For now, we can workaround this by scheduling the return
>     of the
>      > +     * fence descriptors on the main thread.
>      > +     */
>      > +
>      > +    data = g_new0(struct rutabaga_aio_data, 1);
>      > +    data->vr = vr;
>      > +    data->fence = *fence;
>      > +    aio_bh_schedule_oneshot_full(qemu_get_aio_context(),
>      > +                                 virtio_gpu_rutabaga_aio_cb,
>      > +                                 data, "aio");
>      > +}
>      > +
>      > +static void
>      > +virtio_gpu_rutabaga_debug_cb(uint64_t user_data,
>      > +                             const struct rutabaga_debug *debug) {
>      > +
>      > +    if (debug->debug_type == RUTABAGA_DEBUG_ERROR) {
>      > +        error_report("%s", debug->message);
>      > +    } else if (debug->debug_type == RUTABAGA_DEBUG_WARN) {
>      > +        warn_report("%s", debug->message);
>      > +    } else if (debug->debug_type == RUTABAGA_DEBUG_INFO) {
>      > +        info_report("%s", debug->message);
>      > +    }
>      > +}
>      > +
>      > +static int virtio_gpu_rutabaga_init(VirtIOGPU *g, Error **errp)
>      > +{
>      > +    int result;
>      > +    uint64_t capset_mask;
>      > +    struct rutabaga_builder builder = { 0 };
>      > +    char wayland_socket_path[UNIX_PATH_MAX];
>      > +    struct rutabaga_channel channel = { 0 };
>      > +    struct rutabaga_channels channels = { 0 };
>      > +
>      > +    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
>      > +    vr->rutabaga = NULL;
>      > +
>      > +    if (!vr->capset_names) {
>      > +        error_setg(errp, "a capset name from the virtio-gpu spec
>     is required");
>      > +        return -EINVAL;
>      > +    }
>      > +
>      > +    builder.wsi = RUTABAGA_WSI_SURFACELESS;
>      > +    /*
>      > +     * Currently, if WSI is specified, the only valid strings
>     are "surfaceless"
>      > +     * or "headless".  Surfaceless doesn't create a native
>     window surface, but
>      > +     * does copy from the render target to the Pixman buffer if
>     a virtio-gpu
>      > +     * 2D hypercall is issued.  Surfacless is the default.
>      > +     *
>      > +     * Headless is like surfaceless, but doesn't copy to the
>     Pixman buffer. The
>      > +     * use case is automated testing environments where there is
>     no need to view
>      > +     * results.
>      > +     *
>      > +     * In the future, more performant virtio-gpu 2D UI
>     integration may be added.
>      > +     */
>      > +    if (vr->wsi) {
>      > +        if (g_str_equal(vr->wsi, "surfaceless")) {
>      > +            vr->headless = false;
>      > +        } else if (g_str_equal(vr->wsi, "headless")) {
>      > +            vr->headless = true;
>      > +        } else {
>      > +            error_setg(errp, "invalid wsi option selected");
>      > +            return -EINVAL;
>      > +        }
>      > +    }
>      > +
>      > +    result = rutabaga_calculate_capset_mask(vr->capset_names,
>     &capset_mask);
>      > +    if (result) {
>      > +        error_setg(errp, "invalid capset names: %s",
>     vr->capset_names);
>      > +        return result;
>      > +    }
>      > +
>      > +    builder.fence_cb = virtio_gpu_rutabaga_fence_cb;
>      > +    builder.debug_cb = virtio_gpu_rutabaga_debug_cb;
>      > +    builder.capset_mask = capset_mask;
>      > +    builder.user_data = (uint64_t)g;
>      > +
>      > +    /*
>      > +     * If the user doesn't specify the wayland socket path, we
>     try to infer
>      > +     * the socket via a process similar to the one used by
>     libwayland.
>      > +     * libwayland does the following:
>      > +     *
>      > +     * 1) If $WAYLAND_DISPLAY is set, attempt to connect to
>      > +     *    $XDG_RUNTIME_DIR/$WAYLAND_DISPLAY
>      > +     * 2) Otherwise, attempt to connect to
>     $XDG_RUNTIME_DIR/wayland-0
>      > +     * 3) Otherwise, don't pass a wayland socket to rutabaga. If
>     a guest
>      > +     *    wayland proxy is launched, it will fail to work.
>      > +     */
>      > +    channel.channel_type = RUTABAGA_CHANNEL_TYPE_WAYLAND;
>      > +    if (!vr->wayland_socket_path) {
>      > +        const char *runtime_dir = getenv("XDG_RUNTIME_DIR");
>      > +        const char *display = getenv("WAYLAND_DISPLAY");
>      > +        if (!display) {
>      > +            display = "wayland-0";
>      > +        }
>      > +
>      > +        if (runtime_dir) {
>      > +            result = snprintf(wayland_socket_path, UNIX_PATH_MAX,
>      > +                              "%s/%s", runtime_dir, display);
>      > +            if (result > 0 && result < UNIX_PATH_MAX) {
>      > +                channel.channel_name = wayland_socket_path;
>      > +            }
> 
>     As I said in the last email, I think it's better to make a hard
>     error if
>     the user requested RUTABAGA_CAPSET_CROSS_DOMAIN but the default socket
>     path does not fit in wayland_socket_path.
> 
> 
> I mentioned this in the cover-letter to v5, but messed up the commit 
> message of patch 6.  But we do want to be possible to use cross_domain 
> without wayland for following reason:
> 
> "It is possible to use cross-domain without enabling Wayland, for guest
> swapchain allocation [a] which often needs special handling.  We might
> We want to use this capability on MacOS/Windows in the future without
> Wayland, hence we shouldn't have hard errors if the default wayland socket
> isn't found.
> 
> [a] 
> https://android.googlesource.com/platform/external/minigbm/+/refs/heads/main/virtgpu_cross_domain.c <https://android.googlesource.com/platform/external/minigbm/+/refs/heads/main/virtgpu_cross_domain.c>"
> 
> I'll incorporate your other suggestions in v6 though.

What happens on X.org system then? Such a system may have 
XDG_RUNTIME_DIR but should not have WAYLAND_DISPLAY, resulting in 
$XDG_RUNTIME_DIR/wayland-0 passed to Rutabaga.

Patch

diff --git a/hw/display/virtio-gpu-pci-rutabaga.c b/hw/display/virtio-gpu-pci-rutabaga.c
new file mode 100644
index 0000000000..c71173d8ca
--- /dev/null
+++ b/hw/display/virtio-gpu-pci-rutabaga.c
@@ -0,0 +1,48 @@ 
+// SPDX-License-Identifier: GPL-2.0
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qemu/module.h"
+#include "hw/pci/pci.h"
+#include "hw/qdev-properties.h"
+#include "hw/virtio/virtio.h"
+#include "hw/virtio/virtio-bus.h"
+#include "hw/virtio/virtio-gpu-pci.h"
+#include "qom/object.h"
+
+#define TYPE_VIRTIO_GPU_RUTABAGA_PCI "virtio-gpu-rutabaga-pci"
+typedef struct VirtIOGPURutabagaPCI VirtIOGPURutabagaPCI;
+DECLARE_INSTANCE_CHECKER(VirtIOGPURutabagaPCI, VIRTIO_GPU_RUTABAGA_PCI,
+                         TYPE_VIRTIO_GPU_RUTABAGA_PCI)
+
+struct VirtIOGPURutabagaPCI {
+    VirtIOGPUPCIBase parent_obj;
+    VirtIOGPURutabaga vdev;
+};
+
+static void virtio_gpu_rutabaga_initfn(Object *obj)
+{
+    VirtIOGPURutabagaPCI *dev = VIRTIO_GPU_RUTABAGA_PCI(obj);
+
+    virtio_instance_init_common(obj, &dev->vdev, sizeof(dev->vdev),
+                                TYPE_VIRTIO_GPU_RUTABAGA);
+    VIRTIO_GPU_PCI_BASE(obj)->vgpu = VIRTIO_GPU_BASE(&dev->vdev);
+}
+
+static const VirtioPCIDeviceTypeInfo virtio_gpu_rutabaga_pci_info = {
+    .generic_name = TYPE_VIRTIO_GPU_RUTABAGA_PCI,
+    .parent = TYPE_VIRTIO_GPU_PCI_BASE,
+    .instance_size = sizeof(VirtIOGPURutabagaPCI),
+    .instance_init = virtio_gpu_rutabaga_initfn,
+};
+module_obj(TYPE_VIRTIO_GPU_RUTABAGA_PCI);
+module_kconfig(VIRTIO_PCI);
+
+static void virtio_gpu_rutabaga_pci_register_types(void)
+{
+    virtio_pci_types_register(&virtio_gpu_rutabaga_pci_info);
+}
+
+type_init(virtio_gpu_rutabaga_pci_register_types)
+
+module_dep("hw-display-virtio-gpu-pci");
diff --git a/hw/display/virtio-gpu-rutabaga.c b/hw/display/virtio-gpu-rutabaga.c
new file mode 100644
index 0000000000..3f9f106abc
--- /dev/null
+++ b/hw/display/virtio-gpu-rutabaga.c
@@ -0,0 +1,1114 @@ 
+// SPDX-License-Identifier: GPL-2.0
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qemu/error-report.h"
+#include "qemu/iov.h"
+#include "trace.h"
+#include "hw/virtio/virtio.h"
+#include "hw/virtio/virtio-gpu.h"
+#include "hw/virtio/virtio-gpu-pixman.h"
+#include "hw/virtio/virtio-iommu.h"
+
+#include <glib/gmem.h>
+#include <rutabaga_gfx/rutabaga_gfx_ffi.h>
+
+#define CHECK(condition, cmd)                                                 \
+    do {                                                                      \
+        if (!(condition)) {                                                   \
+            error_report("CHECK failed in %s() %s:" "%d", __func__,           \
+                         __FILE__, __LINE__);                                 \
+            (cmd)->error = VIRTIO_GPU_RESP_ERR_UNSPEC;                        \
+            return;                                                           \
+       }                                                                      \
+    } while (0)
+
+/*
+ * This is the size of the char array in struct sock_addr_un. No Wayland socket
+ * can be created with a path longer than this, including the null terminator.
+ */
+#ifndef UNIX_PATH_MAX
+#define UNIX_PATH_MAX sizeof((struct sockaddr_un) {} .sun_path)
+#endif
+
+struct rutabaga_aio_data {
+    struct VirtIOGPURutabaga *vr;
+    struct rutabaga_fence fence;
+};
+
+static void
+virtio_gpu_rutabaga_update_cursor(VirtIOGPU *g, struct virtio_gpu_scanout *s,
+                                  uint32_t resource_id)
+{
+    struct virtio_gpu_simple_resource *res;
+    struct rutabaga_transfer transfer = { 0 };
+    struct iovec transfer_iovec;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    res = virtio_gpu_find_resource(g, resource_id);
+    if (!res) {
+        return;
+    }
+
+    if (res->width != s->current_cursor->width ||
+        res->height != s->current_cursor->height) {
+        return;
+    }
+
+    transfer.x = 0;
+    transfer.y = 0;
+    transfer.z = 0;
+    transfer.w = res->width;
+    transfer.h = res->height;
+    transfer.d = 1;
+
+    transfer_iovec.iov_base = s->current_cursor->data;
+    transfer_iovec.iov_len = res->width * res->height * 4;
+
+    rutabaga_resource_transfer_read(vr->rutabaga, 0,
+                                    resource_id, &transfer,
+                                    &transfer_iovec);
+}
+
+static void
+virtio_gpu_rutabaga_gl_flushed(VirtIOGPUBase *b)
+{
+    VirtIOGPU *g = VIRTIO_GPU(b);
+    virtio_gpu_process_cmdq(g);
+}
+
+static void
+rutabaga_cmd_create_resource_2d(VirtIOGPU *g,
+                                struct virtio_gpu_ctrl_command *cmd)
+{
+    int32_t result;
+    struct rutabaga_create_3d rc_3d = { 0 };
+    struct virtio_gpu_simple_resource *res;
+    struct virtio_gpu_resource_create_2d c2d;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    VIRTIO_GPU_FILL_CMD(c2d);
+    trace_virtio_gpu_cmd_res_create_2d(c2d.resource_id, c2d.format,
+                                       c2d.width, c2d.height);
+
+    rc_3d.target = 2;
+    rc_3d.format = c2d.format;
+    rc_3d.bind = (1 << 1);
+    rc_3d.width = c2d.width;
+    rc_3d.height = c2d.height;
+    rc_3d.depth = 1;
+    rc_3d.array_size = 1;
+    rc_3d.last_level = 0;
+    rc_3d.nr_samples = 0;
+    rc_3d.flags = VIRTIO_GPU_RESOURCE_FLAG_Y_0_TOP;
+
+    result = rutabaga_resource_create_3d(vr->rutabaga, c2d.resource_id, &rc_3d);
+    CHECK(!result, cmd);
+
+    res = g_new0(struct virtio_gpu_simple_resource, 1);
+    res->width = c2d.width;
+    res->height = c2d.height;
+    res->format = c2d.format;
+    res->resource_id = c2d.resource_id;
+
+    QTAILQ_INSERT_HEAD(&g->reslist, res, next);
+}
+
+static void
+rutabaga_cmd_create_resource_3d(VirtIOGPU *g,
+                                struct virtio_gpu_ctrl_command *cmd)
+{
+    int32_t result;
+    struct rutabaga_create_3d rc_3d = { 0 };
+    struct virtio_gpu_simple_resource *res;
+    struct virtio_gpu_resource_create_3d c3d;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    VIRTIO_GPU_FILL_CMD(c3d);
+
+    trace_virtio_gpu_cmd_res_create_3d(c3d.resource_id, c3d.format,
+                                       c3d.width, c3d.height, c3d.depth);
+
+    rc_3d.target = c3d.target;
+    rc_3d.format = c3d.format;
+    rc_3d.bind = c3d.bind;
+    rc_3d.width = c3d.width;
+    rc_3d.height = c3d.height;
+    rc_3d.depth = c3d.depth;
+    rc_3d.array_size = c3d.array_size;
+    rc_3d.last_level = c3d.last_level;
+    rc_3d.nr_samples = c3d.nr_samples;
+    rc_3d.flags = c3d.flags;
+
+    result = rutabaga_resource_create_3d(vr->rutabaga, c3d.resource_id, &rc_3d);
+    CHECK(!result, cmd);
+
+    res = g_new0(struct virtio_gpu_simple_resource, 1);
+    res->width = c3d.width;
+    res->height = c3d.height;
+    res->format = c3d.format;
+    res->resource_id = c3d.resource_id;
+
+    QTAILQ_INSERT_HEAD(&g->reslist, res, next);
+}
+
+static void
+rutabaga_cmd_resource_unref(VirtIOGPU *g,
+                            struct virtio_gpu_ctrl_command *cmd)
+{
+    int32_t result;
+    struct virtio_gpu_simple_resource *res;
+    struct virtio_gpu_resource_unref unref;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    VIRTIO_GPU_FILL_CMD(unref);
+
+    trace_virtio_gpu_cmd_res_unref(unref.resource_id);
+
+    res = virtio_gpu_find_resource(g, unref.resource_id);
+    CHECK(res, cmd);
+
+    result = rutabaga_resource_unref(vr->rutabaga, unref.resource_id);
+    CHECK(!result, cmd);
+
+    if (res->image) {
+        pixman_image_unref(res->image);
+    }
+
+    QTAILQ_REMOVE(&g->reslist, res, next);
+    g_free(res);
+}
+
+static void
+rutabaga_cmd_context_create(VirtIOGPU *g,
+                            struct virtio_gpu_ctrl_command *cmd)
+{
+    int32_t result;
+    struct virtio_gpu_ctx_create cc;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    VIRTIO_GPU_FILL_CMD(cc);
+    trace_virtio_gpu_cmd_ctx_create(cc.hdr.ctx_id,
+                                    cc.debug_name);
+
+    result = rutabaga_context_create(vr->rutabaga, cc.hdr.ctx_id,
+                                     cc.context_init, cc.debug_name, cc.nlen);
+    CHECK(!result, cmd);
+}
+
+static void
+rutabaga_cmd_context_destroy(VirtIOGPU *g,
+                             struct virtio_gpu_ctrl_command *cmd)
+{
+    int32_t result;
+    struct virtio_gpu_ctx_destroy cd;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    VIRTIO_GPU_FILL_CMD(cd);
+    trace_virtio_gpu_cmd_ctx_destroy(cd.hdr.ctx_id);
+
+    result = rutabaga_context_destroy(vr->rutabaga, cd.hdr.ctx_id);
+    CHECK(!result, cmd);
+}
+
+static void
+rutabaga_cmd_resource_flush(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd)
+{
+    int32_t result, i;
+    struct virtio_gpu_scanout *scanout = NULL;
+    struct virtio_gpu_simple_resource *res;
+    struct rutabaga_transfer transfer = { 0 };
+    struct iovec transfer_iovec;
+    struct virtio_gpu_resource_flush rf;
+    bool found = false;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+    if (vr->headless) {
+        return;
+    }
+
+    VIRTIO_GPU_FILL_CMD(rf);
+    trace_virtio_gpu_cmd_res_flush(rf.resource_id,
+                                   rf.r.width, rf.r.height, rf.r.x, rf.r.y);
+
+    res = virtio_gpu_find_resource(g, rf.resource_id);
+    CHECK(res, cmd);
+
+    for (i = 0; i < g->parent_obj.conf.max_outputs; i++) {
+        scanout = &g->parent_obj.scanout[i];
+        if (i == res->scanout_bitmask) {
+            found = true;
+            break;
+        }
+    }
+
+    if (!found) {
+        return;
+    }
+
+    transfer.x = 0;
+    transfer.y = 0;
+    transfer.z = 0;
+    transfer.w = res->width;
+    transfer.h = res->height;
+    transfer.d = 1;
+
+    transfer_iovec.iov_base = pixman_image_get_data(res->image);
+    transfer_iovec.iov_len = res->width * res->height * 4;
+
+    result = rutabaga_resource_transfer_read(vr->rutabaga, 0,
+                                             rf.resource_id, &transfer,
+                                             &transfer_iovec);
+    CHECK(!result, cmd);
+    dpy_gfx_update_full(scanout->con);
+}
+
+static void
+rutabaga_cmd_set_scanout(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd)
+{
+    struct virtio_gpu_simple_resource *res;
+    struct virtio_gpu_scanout *scanout = NULL;
+    struct virtio_gpu_set_scanout ss;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+    if (vr->headless) {
+        return;
+    }
+
+    VIRTIO_GPU_FILL_CMD(ss);
+    trace_virtio_gpu_cmd_set_scanout(ss.scanout_id, ss.resource_id,
+                                     ss.r.width, ss.r.height, ss.r.x, ss.r.y);
+
+    CHECK(ss.scanout_id < VIRTIO_GPU_MAX_SCANOUTS, cmd);
+    scanout = &g->parent_obj.scanout[ss.scanout_id];
+
+    if (ss.resource_id == 0) {
+        return;
+    }
+
+    res = virtio_gpu_find_resource(g, ss.resource_id);
+    CHECK(res, cmd);
+
+    if (!res->image) {
+        pixman_format_code_t pformat;
+        pformat = virtio_gpu_get_pixman_format(res->format);
+        CHECK(pformat, cmd);
+
+        res->image = pixman_image_create_bits(pformat,
+                                              res->width,
+                                              res->height,
+                                              NULL, 0);
+        CHECK(res->image, cmd);
+        pixman_image_ref(res->image);
+    }
+
+    g->parent_obj.enable = 1;
+
+    /* realloc the surface ptr */
+    scanout->ds = qemu_create_displaysurface_pixman(res->image);
+    dpy_gfx_replace_surface(scanout->con, NULL);
+    dpy_gfx_replace_surface(scanout->con, scanout->ds);
+    res->scanout_bitmask = ss.scanout_id;
+}
+
+static void
+rutabaga_cmd_submit_3d(VirtIOGPU *g,
+                       struct virtio_gpu_ctrl_command *cmd)
+{
+    int32_t result;
+    struct virtio_gpu_cmd_submit cs;
+    struct rutabaga_command rutabaga_cmd = { 0 };
+    g_autofree uint8_t *buf = NULL;
+    size_t s;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    VIRTIO_GPU_FILL_CMD(cs);
+    trace_virtio_gpu_cmd_ctx_submit(cs.hdr.ctx_id, cs.size);
+
+    buf = g_new0(uint8_t, cs.size);
+    s = iov_to_buf(cmd->elem.out_sg, cmd->elem.out_num,
+                   sizeof(cs), buf, cs.size);
+    CHECK(s == cs.size, cmd);
+
+    rutabaga_cmd.ctx_id = cs.hdr.ctx_id;
+    rutabaga_cmd.cmd = buf;
+    rutabaga_cmd.cmd_size = cs.size;
+
+    result = rutabaga_submit_command(vr->rutabaga, &rutabaga_cmd);
+    CHECK(!result, cmd);
+}
+
+static void
+rutabaga_cmd_transfer_to_host_2d(VirtIOGPU *g,
+                                 struct virtio_gpu_ctrl_command *cmd)
+{
+    int32_t result;
+    struct rutabaga_transfer transfer = { 0 };
+    struct virtio_gpu_transfer_to_host_2d t2d;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    VIRTIO_GPU_FILL_CMD(t2d);
+    trace_virtio_gpu_cmd_res_xfer_toh_2d(t2d.resource_id);
+
+    transfer.x = t2d.r.x;
+    transfer.y = t2d.r.y;
+    transfer.z = 0;
+    transfer.w = t2d.r.width;
+    transfer.h = t2d.r.height;
+    transfer.d = 1;
+
+    result = rutabaga_resource_transfer_write(vr->rutabaga, 0, t2d.resource_id,
+                                              &transfer);
+    CHECK(!result, cmd);
+}
+
+static void
+rutabaga_cmd_transfer_to_host_3d(VirtIOGPU *g,
+                                 struct virtio_gpu_ctrl_command *cmd)
+{
+    int32_t result;
+    struct rutabaga_transfer transfer = { 0 };
+    struct virtio_gpu_transfer_host_3d t3d;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    VIRTIO_GPU_FILL_CMD(t3d);
+    trace_virtio_gpu_cmd_res_xfer_toh_3d(t3d.resource_id);
+
+    transfer.x = t3d.box.x;
+    transfer.y = t3d.box.y;
+    transfer.z = t3d.box.z;
+    transfer.w = t3d.box.w;
+    transfer.h = t3d.box.h;
+    transfer.d = t3d.box.d;
+    transfer.level = t3d.level;
+    transfer.stride = t3d.stride;
+    transfer.layer_stride = t3d.layer_stride;
+    transfer.offset = t3d.offset;
+
+    result = rutabaga_resource_transfer_write(vr->rutabaga, t3d.hdr.ctx_id,
+                                              t3d.resource_id, &transfer);
+    CHECK(!result, cmd);
+}
+
+static void
+rutabaga_cmd_transfer_from_host_3d(VirtIOGPU *g,
+                                   struct virtio_gpu_ctrl_command *cmd)
+{
+    int32_t result;
+    struct rutabaga_transfer transfer = { 0 };
+    struct virtio_gpu_transfer_host_3d t3d;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    VIRTIO_GPU_FILL_CMD(t3d);
+    trace_virtio_gpu_cmd_res_xfer_fromh_3d(t3d.resource_id);
+
+    transfer.x = t3d.box.x;
+    transfer.y = t3d.box.y;
+    transfer.z = t3d.box.z;
+    transfer.w = t3d.box.w;
+    transfer.h = t3d.box.h;
+    transfer.d = t3d.box.d;
+    transfer.level = t3d.level;
+    transfer.stride = t3d.stride;
+    transfer.layer_stride = t3d.layer_stride;
+    transfer.offset = t3d.offset;
+
+    result = rutabaga_resource_transfer_read(vr->rutabaga, t3d.hdr.ctx_id,
+                                             t3d.resource_id, &transfer, NULL);
+    CHECK(!result, cmd);
+}
+
+static void
+rutabaga_cmd_attach_backing(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd)
+{
+    struct rutabaga_iovecs vecs = { 0 };
+    struct virtio_gpu_simple_resource *res;
+    struct virtio_gpu_resource_attach_backing att_rb;
+    int ret;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    VIRTIO_GPU_FILL_CMD(att_rb);
+    trace_virtio_gpu_cmd_res_back_attach(att_rb.resource_id);
+
+    res = virtio_gpu_find_resource(g, att_rb.resource_id);
+    CHECK(res, cmd);
+    CHECK(!res->iov, cmd);
+
+    ret = virtio_gpu_create_mapping_iov(g, att_rb.nr_entries, sizeof(att_rb),
+                                        cmd, NULL, &res->iov, &res->iov_cnt);
+    CHECK(!ret, cmd);
+
+    vecs.iovecs = res->iov;
+    vecs.num_iovecs = res->iov_cnt;
+
+    ret = rutabaga_resource_attach_backing(vr->rutabaga, att_rb.resource_id,
+                                           &vecs);
+    if (ret != 0) {
+        virtio_gpu_cleanup_mapping(g, res);
+    }
+
+    CHECK(!ret, cmd);
+}
+
+static void
+rutabaga_cmd_detach_backing(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd)
+{
+    struct virtio_gpu_simple_resource *res;
+    struct virtio_gpu_resource_detach_backing detach_rb;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    VIRTIO_GPU_FILL_CMD(detach_rb);
+    trace_virtio_gpu_cmd_res_back_detach(detach_rb.resource_id);
+
+    res = virtio_gpu_find_resource(g, detach_rb.resource_id);
+    CHECK(res, cmd);
+
+    rutabaga_resource_detach_backing(vr->rutabaga,
+                                     detach_rb.resource_id);
+
+    virtio_gpu_cleanup_mapping(g, res);
+}
+
+static void
+rutabaga_cmd_ctx_attach_resource(VirtIOGPU *g,
+                                 struct virtio_gpu_ctrl_command *cmd)
+{
+    int32_t result;
+    struct virtio_gpu_ctx_resource att_res;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    VIRTIO_GPU_FILL_CMD(att_res);
+    trace_virtio_gpu_cmd_ctx_res_attach(att_res.hdr.ctx_id,
+                                        att_res.resource_id);
+
+    result = rutabaga_context_attach_resource(vr->rutabaga, att_res.hdr.ctx_id,
+                                              att_res.resource_id);
+    CHECK(!result, cmd);
+}
+
+static void
+rutabaga_cmd_ctx_detach_resource(VirtIOGPU *g,
+                                 struct virtio_gpu_ctrl_command *cmd)
+{
+    int32_t result;
+    struct virtio_gpu_ctx_resource det_res;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    VIRTIO_GPU_FILL_CMD(det_res);
+    trace_virtio_gpu_cmd_ctx_res_detach(det_res.hdr.ctx_id,
+                                        det_res.resource_id);
+
+    result = rutabaga_context_detach_resource(vr->rutabaga, det_res.hdr.ctx_id,
+                                              det_res.resource_id);
+    CHECK(!result, cmd);
+}
+
+static void
+rutabaga_cmd_get_capset_info(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd)
+{
+    int32_t result;
+    struct virtio_gpu_get_capset_info info;
+    struct virtio_gpu_resp_capset_info resp;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    VIRTIO_GPU_FILL_CMD(info);
+
+    result = rutabaga_get_capset_info(vr->rutabaga, info.capset_index,
+                                      &resp.capset_id, &resp.capset_max_version,
+                                      &resp.capset_max_size);
+    CHECK(!result, cmd);
+
+    resp.hdr.type = VIRTIO_GPU_RESP_OK_CAPSET_INFO;
+    virtio_gpu_ctrl_response(g, cmd, &resp.hdr, sizeof(resp));
+}
+
+static void
+rutabaga_cmd_get_capset(VirtIOGPU *g, struct virtio_gpu_ctrl_command *cmd)
+{
+    int32_t result;
+    struct virtio_gpu_get_capset gc;
+    struct virtio_gpu_resp_capset *resp;
+    uint32_t capset_size;
+    uint32_t current_id;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    VIRTIO_GPU_FILL_CMD(gc);
+    for (uint32_t i = 0; i < vr->num_capsets; i++) {
+        CHECK(i < vr->num_capsets, cmd);
+        result = rutabaga_get_capset_info(vr->rutabaga, i,
+                                          &current_id, &capset_size,
+                                          &capset_size);
+        CHECK(!result, cmd);
+
+        if (current_id == gc.capset_id) {
+            break;
+        }
+    }
+
+    resp = g_malloc0(sizeof(*resp) + capset_size);
+    resp->hdr.type = VIRTIO_GPU_RESP_OK_CAPSET;
+    rutabaga_get_capset(vr->rutabaga, gc.capset_id, gc.capset_version,
+                        resp->capset_data, capset_size);
+
+    virtio_gpu_ctrl_response(g, cmd, &resp->hdr, sizeof(*resp) + capset_size);
+    g_free(resp);
+}
+
+static void
+rutabaga_cmd_resource_create_blob(VirtIOGPU *g,
+                                  struct virtio_gpu_ctrl_command *cmd)
+{
+    int result;
+    struct rutabaga_iovecs vecs = { 0 };
+    g_autofree struct virtio_gpu_simple_resource *res = NULL;
+    struct virtio_gpu_resource_create_blob cblob;
+    struct rutabaga_create_blob rc_blob = { 0 };
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    VIRTIO_GPU_FILL_CMD(cblob);
+    trace_virtio_gpu_cmd_res_create_blob(cblob.resource_id, cblob.size);
+
+    CHECK(cblob.resource_id != 0, cmd);
+
+    res = g_new0(struct virtio_gpu_simple_resource, 1);
+
+    res->resource_id = cblob.resource_id;
+    res->blob_size = cblob.size;
+
+    if (cblob.blob_mem != VIRTIO_GPU_BLOB_MEM_HOST3D) {
+        result = virtio_gpu_create_mapping_iov(g, cblob.nr_entries,
+                                               sizeof(cblob), cmd, &res->addrs,
+                                               &res->iov, &res->iov_cnt);
+        CHECK(!result, cmd);
+    }
+
+    rc_blob.blob_id = cblob.blob_id;
+    rc_blob.blob_mem = cblob.blob_mem;
+    rc_blob.blob_flags = cblob.blob_flags;
+    rc_blob.size = cblob.size;
+
+    vecs.iovecs = res->iov;
+    vecs.num_iovecs = res->iov_cnt;
+
+    result = rutabaga_resource_create_blob(vr->rutabaga, cblob.hdr.ctx_id,
+                                           cblob.resource_id, &rc_blob, &vecs,
+                                           NULL);
+
+    if (result && cblob.blob_mem != VIRTIO_GPU_BLOB_MEM_HOST3D) {
+        virtio_gpu_cleanup_mapping(g, res);
+    }
+
+    CHECK(!result, cmd);
+
+    QTAILQ_INSERT_HEAD(&g->reslist, res, next);
+    res = NULL;
+}
+
+static void
+rutabaga_cmd_resource_map_blob(VirtIOGPU *g,
+                               struct virtio_gpu_ctrl_command *cmd)
+{
+    int32_t result;
+    uint32_t map_info = 0;
+    uint32_t slot = 0;
+    struct virtio_gpu_simple_resource *res;
+    struct rutabaga_mapping mapping = { 0 };
+    struct virtio_gpu_resource_map_blob mblob;
+    struct virtio_gpu_resp_map_info resp = { 0 };
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    VIRTIO_GPU_FILL_CMD(mblob);
+
+    CHECK(mblob.resource_id != 0, cmd);
+
+    res = virtio_gpu_find_resource(g, mblob.resource_id);
+    CHECK(res, cmd);
+
+    result = rutabaga_resource_map_info(vr->rutabaga, mblob.resource_id,
+                                        &map_info);
+    CHECK(!result, cmd);
+
+    /*
+     * RUTABAGA_MAP_ACCESS_* flags are not part of the virtio-gpu spec, but do
+     * exist to potentially allow the hypervisor to restrict write access to
+     * memory. QEMU does not need to use this functionality at the moment.
+     */
+    resp.map_info = map_info & RUTABAGA_MAP_CACHE_MASK;
+
+    result = rutabaga_resource_map(vr->rutabaga, mblob.resource_id, &mapping);
+    CHECK(!result, cmd);
+
+    for (slot = 0; slot < MAX_SLOTS; slot++) {
+        if (vr->memory_regions[slot].used) {
+            continue;
+        }
+
+        MemoryRegion *mr = &(vr->memory_regions[slot].mr);
+        memory_region_init_ram_ptr(mr, NULL, "blob", mapping.size,
+                                   mapping.ptr);
+        memory_region_add_subregion(&g->parent_obj.hostmem,
+                                    mblob.offset, mr);
+        vr->memory_regions[slot].resource_id = mblob.resource_id;
+        vr->memory_regions[slot].used = 1;
+        break;
+    }
+
+    if (slot >= MAX_SLOTS) {
+        result = rutabaga_resource_unmap(vr->rutabaga, mblob.resource_id);
+        CHECK(!result, cmd);
+    }
+
+    CHECK(slot < MAX_SLOTS, cmd);
+
+    resp.hdr.type = VIRTIO_GPU_RESP_OK_MAP_INFO;
+    virtio_gpu_ctrl_response(g, cmd, &resp.hdr, sizeof(resp));
+}
+
+static void
+rutabaga_cmd_resource_unmap_blob(VirtIOGPU *g,
+                                 struct virtio_gpu_ctrl_command *cmd)
+{
+    int32_t result;
+    uint32_t slot = 0;
+    struct virtio_gpu_simple_resource *res;
+    struct virtio_gpu_resource_unmap_blob ublob;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    VIRTIO_GPU_FILL_CMD(ublob);
+
+    CHECK(ublob.resource_id != 0, cmd);
+
+    res = virtio_gpu_find_resource(g, ublob.resource_id);
+    CHECK(res, cmd);
+
+    for (slot = 0; slot < MAX_SLOTS; slot++) {
+        if (vr->memory_regions[slot].resource_id != ublob.resource_id) {
+            continue;
+        }
+
+        MemoryRegion *mr = &(vr->memory_regions[slot].mr);
+        memory_region_del_subregion(&g->parent_obj.hostmem, mr);
+
+        vr->memory_regions[slot].resource_id = 0;
+        vr->memory_regions[slot].used = 0;
+        break;
+    }
+
+    CHECK(slot < MAX_SLOTS, cmd);
+    result = rutabaga_resource_unmap(vr->rutabaga, res->resource_id);
+    CHECK(!result, cmd);
+}
+
+static void
+virtio_gpu_rutabaga_process_cmd(VirtIOGPU *g,
+                                struct virtio_gpu_ctrl_command *cmd)
+{
+    struct rutabaga_fence fence = { 0 };
+    int32_t result;
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    VIRTIO_GPU_FILL_CMD(cmd->cmd_hdr);
+
+    switch (cmd->cmd_hdr.type) {
+    case VIRTIO_GPU_CMD_CTX_CREATE:
+        rutabaga_cmd_context_create(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_CTX_DESTROY:
+        rutabaga_cmd_context_destroy(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_RESOURCE_CREATE_2D:
+        rutabaga_cmd_create_resource_2d(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_RESOURCE_CREATE_3D:
+        rutabaga_cmd_create_resource_3d(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_SUBMIT_3D:
+        rutabaga_cmd_submit_3d(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_TRANSFER_TO_HOST_2D:
+        rutabaga_cmd_transfer_to_host_2d(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_TRANSFER_TO_HOST_3D:
+        rutabaga_cmd_transfer_to_host_3d(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_TRANSFER_FROM_HOST_3D:
+        rutabaga_cmd_transfer_from_host_3d(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_RESOURCE_ATTACH_BACKING:
+        rutabaga_cmd_attach_backing(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_RESOURCE_DETACH_BACKING:
+        rutabaga_cmd_detach_backing(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_SET_SCANOUT:
+        rutabaga_cmd_set_scanout(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_RESOURCE_FLUSH:
+        rutabaga_cmd_resource_flush(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_RESOURCE_UNREF:
+        rutabaga_cmd_resource_unref(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_CTX_ATTACH_RESOURCE:
+        rutabaga_cmd_ctx_attach_resource(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_CTX_DETACH_RESOURCE:
+        rutabaga_cmd_ctx_detach_resource(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_GET_CAPSET_INFO:
+        rutabaga_cmd_get_capset_info(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_GET_CAPSET:
+        rutabaga_cmd_get_capset(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_GET_DISPLAY_INFO:
+        virtio_gpu_get_display_info(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_GET_EDID:
+        virtio_gpu_get_edid(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_RESOURCE_CREATE_BLOB:
+        rutabaga_cmd_resource_create_blob(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_RESOURCE_MAP_BLOB:
+        rutabaga_cmd_resource_map_blob(g, cmd);
+        break;
+    case VIRTIO_GPU_CMD_RESOURCE_UNMAP_BLOB:
+        rutabaga_cmd_resource_unmap_blob(g, cmd);
+        break;
+    default:
+        cmd->error = VIRTIO_GPU_RESP_ERR_UNSPEC;
+        break;
+    }
+
+    if (cmd->finished) {
+        return;
+    }
+    if (cmd->error) {
+        error_report("%s: ctrl 0x%x, error 0x%x", __func__,
+                     cmd->cmd_hdr.type, cmd->error);
+        virtio_gpu_ctrl_response_nodata(g, cmd, cmd->error);
+        return;
+    }
+    if (!(cmd->cmd_hdr.flags & VIRTIO_GPU_FLAG_FENCE)) {
+        virtio_gpu_ctrl_response_nodata(g, cmd, VIRTIO_GPU_RESP_OK_NODATA);
+        return;
+    }
+
+    fence.flags = cmd->cmd_hdr.flags;
+    fence.ctx_id = cmd->cmd_hdr.ctx_id;
+    fence.fence_id = cmd->cmd_hdr.fence_id;
+    fence.ring_idx = cmd->cmd_hdr.ring_idx;
+
+    trace_virtio_gpu_fence_ctrl(cmd->cmd_hdr.fence_id, cmd->cmd_hdr.type);
+
+    result = rutabaga_create_fence(vr->rutabaga, &fence);
+    CHECK(!result, cmd);
+}
+
+static void
+virtio_gpu_rutabaga_aio_cb(void *opaque)
+{
+    struct rutabaga_aio_data *data = opaque;
+    VirtIOGPU *g = VIRTIO_GPU(data->vr);
+    struct rutabaga_fence fence_data = data->fence;
+    struct virtio_gpu_ctrl_command *cmd, *tmp;
+
+    uint32_t signaled_ctx_specific = fence_data.flags &
+                                     RUTABAGA_FLAG_INFO_RING_IDX;
+
+    QTAILQ_FOREACH_SAFE(cmd, &g->fenceq, next, tmp) {
+        /*
+         * Due to context specific timelines.
+         */
+        uint32_t target_ctx_specific = cmd->cmd_hdr.flags &
+                                       RUTABAGA_FLAG_INFO_RING_IDX;
+
+        if (signaled_ctx_specific != target_ctx_specific) {
+            continue;
+        }
+
+        if (signaled_ctx_specific &&
+           (cmd->cmd_hdr.ring_idx != fence_data.ring_idx)) {
+            continue;
+        }
+
+        if (cmd->cmd_hdr.fence_id > fence_data.fence_id) {
+            continue;
+        }
+
+        trace_virtio_gpu_fence_resp(cmd->cmd_hdr.fence_id);
+        virtio_gpu_ctrl_response_nodata(g, cmd, VIRTIO_GPU_RESP_OK_NODATA);
+        QTAILQ_REMOVE(&g->fenceq, cmd, next);
+        g_free(cmd);
+    }
+
+    g_free(data);
+}
+
+static void
+virtio_gpu_rutabaga_fence_cb(uint64_t user_data,
+                             const struct rutabaga_fence *fence) {
+    struct rutabaga_aio_data *data;
+    VirtIOGPU *g = (VirtIOGPU *)user_data;
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    /*
+     * gfxstream and both cross-domain (and even newer versions virglrenderer:
+     * see VIRGL_RENDERER_ASYNC_FENCE_CB) like to signal fence completion on
+     * threads ("callback threads") that are different from the thread that
+     * processes the command queue ("main thread").
+     *
+     * crosvm and other virtio-gpu 1.1 implementations enable callback threads
+     * via locking.  However, on QEMU a deadlock is observed if
+     * virtio_gpu_ctrl_response_nodata(..) [used in the fence callback] is used
+     * from a thread that is not the main thread.
+     *
+     * The reason is QEMU's internal locking is designed to work with QEMU
+     * threads (see rcu_register_thread()) and not generic C/C++/Rust threads.
+     * For now, we can workaround this by scheduling the return of the
+     * fence descriptors on the main thread.
+     */
+
+    data = g_new0(struct rutabaga_aio_data, 1);
+    data->vr = vr;
+    data->fence = *fence;
+    aio_bh_schedule_oneshot_full(qemu_get_aio_context(),
+                                 virtio_gpu_rutabaga_aio_cb,
+                                 data, "aio");
+}
+
+static void
+virtio_gpu_rutabaga_debug_cb(uint64_t user_data,
+                             const struct rutabaga_debug *debug) {
+
+    if (debug->debug_type == RUTABAGA_DEBUG_ERROR) {
+        error_report("%s", debug->message);
+    } else if (debug->debug_type == RUTABAGA_DEBUG_WARN) {
+        warn_report("%s", debug->message);
+    } else if (debug->debug_type == RUTABAGA_DEBUG_INFO) {
+        info_report("%s", debug->message);
+    }
+}
+
+static int virtio_gpu_rutabaga_init(VirtIOGPU *g, Error **errp)
+{
+    int result;
+    uint64_t capset_mask;
+    struct rutabaga_builder builder = { 0 };
+    char wayland_socket_path[UNIX_PATH_MAX];
+    struct rutabaga_channel channel = { 0 };
+    struct rutabaga_channels channels = { 0 };
+
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+    vr->rutabaga = NULL;
+
+    if (!vr->capset_names) {
+        error_setg(errp, "a capset name from the virtio-gpu spec is required");
+        return -EINVAL;
+    }
+
+    builder.wsi = RUTABAGA_WSI_SURFACELESS;
+    /*
+     * Currently, if WSI is specified, the only valid strings are "surfaceless"
+     * or "headless".  Surfaceless doesn't create a native window surface, but
+     * does copy from the render target to the Pixman buffer if a virtio-gpu
+     * 2D hypercall is issued.  Surfacless is the default.
+     *
+     * Headless is like surfaceless, but doesn't copy to the Pixman buffer. The
+     * use case is automated testing environments where there is no need to view
+     * results.
+     *
+     * In the future, more performant virtio-gpu 2D UI integration may be added.
+     */
+    if (vr->wsi) {
+        if (g_str_equal(vr->wsi, "surfaceless")) {
+            vr->headless = false;
+        } else if (g_str_equal(vr->wsi, "headless")) {
+            vr->headless = true;
+        } else {
+            error_setg(errp, "invalid wsi option selected");
+            return -EINVAL;
+        }
+    }
+
+    result = rutabaga_calculate_capset_mask(vr->capset_names, &capset_mask);
+    if (result) {
+        error_setg(errp, "invalid capset names: %s", vr->capset_names);
+        return result;
+    }
+
+    builder.fence_cb = virtio_gpu_rutabaga_fence_cb;
+    builder.debug_cb = virtio_gpu_rutabaga_debug_cb;
+    builder.capset_mask = capset_mask;
+    builder.user_data = (uint64_t)g;
+
+    /*
+     * If the user doesn't specify the wayland socket path, we try to infer
+     * the socket via a process similar to the one used by libwayland.
+     * libwayland does the following:
+     *
+     * 1) If $WAYLAND_DISPLAY is set, attempt to connect to
+     *    $XDG_RUNTIME_DIR/$WAYLAND_DISPLAY
+     * 2) Otherwise, attempt to connect to $XDG_RUNTIME_DIR/wayland-0
+     * 3) Otherwise, don't pass a wayland socket to rutabaga. If a guest
+     *    wayland proxy is launched, it will fail to work.
+     */
+    channel.channel_type = RUTABAGA_CHANNEL_TYPE_WAYLAND;
+    if (!vr->wayland_socket_path) {
+        const char *runtime_dir = getenv("XDG_RUNTIME_DIR");
+        const char *display = getenv("WAYLAND_DISPLAY");
+        if (!display) {
+            display = "wayland-0";
+        }
+
+        if (runtime_dir) {
+            result = snprintf(wayland_socket_path, UNIX_PATH_MAX,
+                              "%s/%s", runtime_dir, display);
+            if (result > 0 && result < UNIX_PATH_MAX) {
+                channel.channel_name = wayland_socket_path;
+            }
+        }
+    } else {
+        channel.channel_name = vr->wayland_socket_path;
+    }
+
+    if ((builder.capset_mask & (1 << RUTABAGA_CAPSET_CROSS_DOMAIN))) {
+        if (channel.channel_name) {
+            channels.channels = &channel;
+            channels.num_channels = 1;
+            builder.channels = &channels;
+        }
+    }
+
+    result = rutabaga_init(&builder, &vr->rutabaga);
+    return result;
+}
+
+static int virtio_gpu_rutabaga_get_num_capsets(VirtIOGPU *g)
+{
+    int result;
+    uint32_t num_capsets;
+    VirtIOGPURutabaga *vr = VIRTIO_GPU_RUTABAGA(g);
+
+    result = rutabaga_get_num_capsets(vr->rutabaga, &num_capsets);
+    if (result) {
+        error_report("Failed to get capsets");
+        return 0;
+    }
+    vr->num_capsets = num_capsets;
+    return num_capsets;
+}
+
+static void virtio_gpu_rutabaga_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
+{
+    VirtIOGPU *g = VIRTIO_GPU(vdev);
+    struct virtio_gpu_ctrl_command *cmd;
+
+    if (!virtio_queue_ready(vq)) {
+        return;
+    }
+
+    cmd = virtqueue_pop(vq, sizeof(struct virtio_gpu_ctrl_command));
+    while (cmd) {
+        cmd->vq = vq;
+        cmd->error = 0;
+        cmd->finished = false;
+        QTAILQ_INSERT_TAIL(&g->cmdq, cmd, next);
+        cmd = virtqueue_pop(vq, sizeof(struct virtio_gpu_ctrl_command));
+    }
+
+    virtio_gpu_process_cmdq(g);
+}
+
+static void virtio_gpu_rutabaga_realize(DeviceState *qdev, Error **errp)
+{
+    int num_capsets;
+    VirtIOGPUBase *bdev = VIRTIO_GPU_BASE(qdev);
+    VirtIOGPU *gpudev = VIRTIO_GPU(qdev);
+
+#if HOST_BIG_ENDIAN
+    error_setg(errp, "rutabaga is not supported on bigendian platforms");
+    return;
+#endif
+
+    int result = virtio_gpu_rutabaga_init(gpudev, errp);
+    if (result) {
+        error_setg(errp, "virtio_gpu_rutabaga_init failed");
+        return;
+    }
+
+    num_capsets = virtio_gpu_rutabaga_get_num_capsets(gpudev);
+    if (!num_capsets) {
+        return;
+    }
+
+    bdev->conf.flags |= (1 << VIRTIO_GPU_FLAG_RUTABAGA_ENABLED);
+    bdev->conf.flags |= (1 << VIRTIO_GPU_FLAG_BLOB_ENABLED);
+    bdev->conf.flags |= (1 << VIRTIO_GPU_FLAG_CONTEXT_INIT_ENABLED);
+
+    bdev->virtio_config.num_capsets = num_capsets;
+    virtio_gpu_device_realize(qdev, errp);
+}
+
+static Property virtio_gpu_rutabaga_properties[] = {
+    DEFINE_PROP_STRING("capset_names", VirtIOGPURutabaga, capset_names),
+    DEFINE_PROP_STRING("wayland_socket_path", VirtIOGPURutabaga,
+                       wayland_socket_path),
+    DEFINE_PROP_STRING("wsi", VirtIOGPURutabaga, wsi),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void virtio_gpu_rutabaga_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
+    VirtIOGPUBaseClass *vbc = VIRTIO_GPU_BASE_CLASS(klass);
+    VirtIOGPUClass *vgc = VIRTIO_GPU_CLASS(klass);
+
+    vbc->gl_flushed = virtio_gpu_rutabaga_gl_flushed;
+    vgc->handle_ctrl = virtio_gpu_rutabaga_handle_ctrl;
+    vgc->process_cmd = virtio_gpu_rutabaga_process_cmd;
+    vgc->update_cursor_data = virtio_gpu_rutabaga_update_cursor;
+
+    vdc->realize = virtio_gpu_rutabaga_realize;
+    device_class_set_props(dc, virtio_gpu_rutabaga_properties);
+}
+
+static const TypeInfo virtio_gpu_rutabaga_info = {
+    .name = TYPE_VIRTIO_GPU_RUTABAGA,
+    .parent = TYPE_VIRTIO_GPU,
+    .instance_size = sizeof(VirtIOGPURutabaga),
+    .class_init = virtio_gpu_rutabaga_class_init,
+};
+module_obj(TYPE_VIRTIO_GPU_RUTABAGA);
+module_kconfig(VIRTIO_GPU);
+
+static void virtio_register_types(void)
+{
+    type_register_static(&virtio_gpu_rutabaga_info);
+}
+
+type_init(virtio_register_types)
+
+module_dep("hw-display-virtio-gpu");
diff --git a/hw/display/virtio-vga-rutabaga.c b/hw/display/virtio-vga-rutabaga.c
new file mode 100644
index 0000000000..2b2ffed8a6
--- /dev/null
+++ b/hw/display/virtio-vga-rutabaga.c
@@ -0,0 +1,51 @@ 
+// SPDX-License-Identifier: GPL-2.0
+
+#include "qemu/osdep.h"
+#include "hw/pci/pci.h"
+#include "hw/qdev-properties.h"
+#include "hw/virtio/virtio-gpu.h"
+#include "hw/display/vga.h"
+#include "qapi/error.h"
+#include "qemu/module.h"
+#include "virtio-vga.h"
+#include "qom/object.h"
+
+#define TYPE_VIRTIO_VGA_RUTABAGA "virtio-vga-rutabaga"
+
+typedef struct VirtIOVGARutabaga VirtIOVGARutabaga;
+DECLARE_INSTANCE_CHECKER(VirtIOVGARutabaga, VIRTIO_VGA_RUTABAGA,
+                         TYPE_VIRTIO_VGA_RUTABAGA)
+
+struct VirtIOVGARutabaga {
+    VirtIOVGABase parent_obj;
+    VirtIOGPURutabaga vdev;
+};
+
+static void virtio_vga_rutabaga_inst_initfn(Object *obj)
+{
+    VirtIOVGARutabaga *dev = VIRTIO_VGA_RUTABAGA(obj);
+
+    virtio_instance_init_common(obj, &dev->vdev, sizeof(dev->vdev),
+                                TYPE_VIRTIO_GPU_RUTABAGA);
+    VIRTIO_VGA_BASE(dev)->vgpu = VIRTIO_GPU_BASE(&dev->vdev);
+}
+
+static VirtioPCIDeviceTypeInfo virtio_vga_rutabaga_info = {
+    .generic_name  = TYPE_VIRTIO_VGA_RUTABAGA,
+    .parent        = TYPE_VIRTIO_VGA_BASE,
+    .instance_size = sizeof(VirtIOVGARutabaga),
+    .instance_init = virtio_vga_rutabaga_inst_initfn,
+};
+module_obj(TYPE_VIRTIO_VGA_RUTABAGA);
+module_kconfig(VIRTIO_VGA);
+
+static void virtio_vga_register_types(void)
+{
+    if (have_vga) {
+        virtio_pci_types_register(&virtio_vga_rutabaga_info);
+    }
+}
+
+type_init(virtio_vga_register_types)
+
+module_dep("hw-display-virtio-vga");