[v3,07/12] vfio-user: handle PCI config space accesses

Commit Message

Jag Raman Oct. 11, 2021, 5:31 a.m. UTC

Define and register handlers for PCI config space accesses

Signed-off-by: Elena Ufimtseva <[e-mail]>
Signed-off-by: John G Johnson <[e-mail]>
Signed-off-by: Jagannathan Raman <[e-mail]>
---
 hw/remote/vfio-user-obj.c | 45 +++++++++++++++++++++++++++++++++++++++
 hw/remote/trace-events    |  2 ++
 2 files changed, 47 insertions(+)

Comments

Stefan Hajnoczi Oct. 27, 2021, 4:35 p.m. UTC | #1

On Mon, Oct 11, 2021 at 01:31:12AM -0400, Jagannathan Raman wrote:
> +static ssize_t vfu_object_cfg_access(vfu_ctx_t *vfu_ctx, char * const buf,
> +                                     size_t count, loff_t offset,
> +                                     const bool is_write)
> +{
> +    VfuObject *o = vfu_get_private(vfu_ctx);
> +    uint32_t pci_access_width = sizeof(uint32_t);
> +    size_t bytes = count;
> +    uint32_t val = 0;
> +    char *ptr = buf;
> +    int len;
> +
> +    while (bytes > 0) {
> +        len = (bytes > pci_access_width) ? pci_access_width : bytes;
> +        if (is_write) {
> +            memcpy(&val, ptr, len);
> +            pci_host_config_write_common(o->pci_dev, offset,
> +                                         pci_config_size(o->pci_dev),
> +                                         val, len);
> +            trace_vfu_cfg_write(offset, val);
> +        } else {
> +            val = pci_host_config_read_common(o->pci_dev, offset,
> +                                              pci_config_size(o->pci_dev), len);
> +            memcpy(ptr, &val, len);
> +            trace_vfu_cfg_read(offset, val);
> +        }

pci_host_config_read/write_common() work with host-endian values. What
is the endianness of buf?

Patch

diff --git a/hw/remote/vfio-user-obj.c b/hw/remote/vfio-user-obj.c
index 05f7fff19c..df5843c388 100644
--- a/hw/remote/vfio-user-obj.c
+++ b/hw/remote/vfio-user-obj.c
@@ -43,6 +43,7 @@ 
 #include "qapi/qapi-visit-sockets.h"
 #include "qemu/notify.h"
 #include "qemu/thread.h"
+#include "qemu/main-loop.h"
 #include "sysemu/sysemu.h"
 #include "libvfio-user.h"
 #include "hw/qdev-core.h"
@@ -160,6 +161,39 @@  retry_attach:
     qemu_set_fd_handler(o->vfu_poll_fd, vfu_object_ctx_run, NULL, o);
 }
 
+static ssize_t vfu_object_cfg_access(vfu_ctx_t *vfu_ctx, char * const buf,
+                                     size_t count, loff_t offset,
+                                     const bool is_write)
+{
+    VfuObject *o = vfu_get_private(vfu_ctx);
+    uint32_t pci_access_width = sizeof(uint32_t);
+    size_t bytes = count;
+    uint32_t val = 0;
+    char *ptr = buf;
+    int len;
+
+    while (bytes > 0) {
+        len = (bytes > pci_access_width) ? pci_access_width : bytes;
+        if (is_write) {
+            memcpy(&val, ptr, len);
+            pci_host_config_write_common(o->pci_dev, offset,
+                                         pci_config_size(o->pci_dev),
+                                         val, len);
+            trace_vfu_cfg_write(offset, val);
+        } else {
+            val = pci_host_config_read_common(o->pci_dev, offset,
+                                              pci_config_size(o->pci_dev), len);
+            memcpy(ptr, &val, len);
+            trace_vfu_cfg_read(offset, val);
+        }
+        offset += len;
+        ptr += len;
+        bytes -= len;
+    }
+
+    return count;
+}
+
 /*
  * vfio-user-server depends on the availability of the 'socket' and 'device'
  * properties. It also depends on devices instantiated in QEMU. These
@@ -209,6 +243,17 @@  static void vfu_object_machine_done(Notifier *notifier, void *data)
         return;
     }
 
+    ret = vfu_setup_region(o->vfu_ctx, VFU_PCI_DEV_CFG_REGION_IDX,
+                           pci_config_size(o->pci_dev), &vfu_object_cfg_access,
+                           VFU_REGION_FLAG_RW | VFU_REGION_FLAG_ALWAYS_CB,
+                           NULL, 0, -1, 0);
+    if (ret < 0) {
+        error_setg(&error_abort,
+                   "vfu: Failed to setup config space handlers for %s- %s",
+                   o->device, strerror(errno));
+        return;
+    }
+
     ret = vfu_realize_ctx(o->vfu_ctx);
     if (ret < 0) {
         error_setg(&error_abort, "vfu: Failed to realize device %s- %s",
diff --git a/hw/remote/trace-events b/hw/remote/trace-events
index 7da12f0d96..2ef7884346 100644
--- a/hw/remote/trace-events
+++ b/hw/remote/trace-events
@@ -5,3 +5,5 @@  mpqemu_recv_io_error(int cmd, int size, int nfds) "failed to receive %d size %d,
 
 # vfio-user-obj.c
 vfu_prop(const char *prop, const char *val) "vfu: setting %s as %s"
+vfu_cfg_read(uint32_t offset, uint32_t val) "vfu: cfg: 0x%u -> 0x%x"
+vfu_cfg_write(uint32_t offset, uint32_t val) "vfu: cfg: 0x%u <- 0x%x"