[v6,11/19] vfio-user: handle PCI config space accesses

Commit Message

Jag Raman Feb. 17, 2022, 7:48 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]>
Reviewed-by: Stefan Hajnoczi <[e-mail]>
---
 hw/remote/vfio-user-obj.c | 45 +++++++++++++++++++++++++++++++++++++++
 hw/remote/trace-events    |  2 ++
 2 files changed, 47 insertions(+)

Comments

Stefan Hajnoczi Feb. 22, 2022, 11:09 a.m. UTC | #1

On Thu, Feb 17, 2022 at 02:48:58AM -0500, Jagannathan Raman wrote:
> 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]>
> Reviewed-by: Stefan Hajnoczi <[e-mail]>
> ---
>  hw/remote/vfio-user-obj.c | 45 +++++++++++++++++++++++++++++++++++++++
>  hw/remote/trace-events    |  2 ++
>  2 files changed, 47 insertions(+)

hw/pci/pci.c:pci_update_mappings() will unmap/map BARs when the
vfio-user client touches BARs. Please add a comment that the remote
machine type never dispatches memory accesses in the global memory address
space and therefore we don't care that multiple remote devices may set
up conflicting Memory and I/O Space BARs.

Jag Raman Feb. 28, 2022, 7:23 p.m. UTC | #2

> On Feb 22, 2022, at 6:09 AM, Stefan Hajnoczi <[e-mail]> wrote:
> 
> On Thu, Feb 17, 2022 at 02:48:58AM -0500, Jagannathan Raman wrote:
>> 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]>
>> Reviewed-by: Stefan Hajnoczi <[e-mail]>
>> ---
>> hw/remote/vfio-user-obj.c | 45 +++++++++++++++++++++++++++++++++++++++
>> hw/remote/trace-events    |  2 ++
>> 2 files changed, 47 insertions(+)
> 
> hw/pci/pci.c:pci_update_mappings() will unmap/map BARs when the
> vfio-user client touches BARs. Please add a comment that the remote
> machine type never dispatches memory accesses in the global memory address
> space and therefore we don't care that multiple remote devices may set
> up conflicting Memory and I/O Space BARs.

OK, will do.

Thank you!
--
Jag

Patch

diff --git a/hw/remote/vfio-user-obj.c b/hw/remote/vfio-user-obj.c
index 384ec4612d..4c4280d603 100644
--- a/hw/remote/vfio-user-obj.c
+++ b/hw/remote/vfio-user-obj.c
@@ -47,6 +47,7 @@ 
 #include "qapi/qapi-events-misc.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"
@@ -217,6 +218,39 @@  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;
+}
+
 /*
  * TYPE_VFU_OBJECT depends on the availability of the 'socket' and 'device'
  * properties. It also depends on devices instantiated in QEMU. These
@@ -293,6 +327,17 @@  static void vfu_object_init_ctx(VfuObject *o, Error **errp)
                TYPE_VFU_OBJECT, o->device);
     qdev_add_unplug_blocker(DEVICE(o->pci_dev), o->unplug_blocker);
 
+    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(errp,
+                   "vfu: Failed to setup config space handlers for %s- %s",
+                   o->device, strerror(errno));
+        goto fail;
+    }
+
     ret = vfu_realize_ctx(o->vfu_ctx);
     if (ret < 0) {
         error_setg(errp, "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"