Re: [PATCH v8 4/4] drm/virtio: wire blob ioctl creation to userptr objects

[Huang, Honglei]

On 9/19/2026 10:28 PM, Akihiko Odaki wrote:
On 2026/09/18 18:59, Honglei Huang wrote:
Integrate userptr into the blob resource creation ioctl.

- A non-zero userptr selects virtio_gpu_userptr_create()
- Reject userptr unless blob_mem is VIRTGPU_BLOB_MEM_GUEST
- Reject VIRTGPU_BLOB_FLAG_USE_READONLY unless the device
   advertised VIRTIO_GPU_F_BLOB_READONLY
- Advertise VIRTGPU_PARAM_USERPTR and VIRTGPU_PARAM_BLOB_READONLY

Signed-off-by: Honglei Huang <hongh...@amd.com>
---
  drivers/gpu/drm/virtio/virtgpu_debugfs.c |  1 +
  drivers/gpu/drm/virtio/virtgpu_ioctl.c   | 35 ++++++++++++++++++++----
  drivers/gpu/drm/virtio/virtgpu_kms.c     |  8 ++++--
  3 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_debugfs.c b/drivers/gpu/ 
drm/virtio/virtgpu_debugfs.c
index 3a68a16b58..b8b9b40584 100644
--- a/drivers/gpu/drm/virtio/virtgpu_debugfs.c
+++ b/drivers/gpu/drm/virtio/virtgpu_debugfs.c
@@ -55,6 +55,7 @@ static int virtio_gpu_features(struct seq_file *m, 
void *data)
                  vgdev->has_resource_assign_uuid);
      virtio_gpu_add_bool(m, "blob resources", vgdev->has_resource_blob);
+    virtio_gpu_add_bool(m, "blob readonly", vgdev->has_blob_readonly);
      virtio_gpu_add_bool(m, "context init", vgdev->has_context_init);
      virtio_gpu_add_int(m, "cap sets", vgdev->num_capsets);
      virtio_gpu_add_int(m, "scanouts", vgdev->num_scanouts);
diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/ 
virtio/virtgpu_ioctl.c
index 3d8e4ccdb7..3dc058e50e 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -36,7 +36,10 @@
  #define VIRTGPU_BLOB_FLAG_USE_MASK (VIRTGPU_BLOB_FLAG_USE_MAPPABLE | \
                      VIRTGPU_BLOB_FLAG_USE_SHAREABLE | \
-                    VIRTGPU_BLOB_FLAG_USE_CROSS_DEVICE)
+                    VIRTGPU_BLOB_FLAG_USE_CROSS_DEVICE | \
+                    VIRTGPU_BLOB_FLAG_USE_READONLY)
+
+#define VIRTGPU_BLOB_HINT_MASK DRM_VIRTGPU_BLOB_FLAG_HINT_DEFER_MAPPING
  /* Must be called with &virtio_gpu_fpriv.struct_mutex held. */
  static void virtio_gpu_create_context_locked(struct 
virtio_gpu_device *vgdev,
@@ -122,6 +125,12 @@ static int virtio_gpu_getparam_ioctl(struct 
drm_device *dev, void *data,
              return -ENOENT;
          value = vgdev->blob_alignment;
          break;
+    case VIRTGPU_PARAM_USERPTR:
+        value = 1;
+        break;
+    case VIRTGPU_PARAM_BLOB_READONLY:
+        value = vgdev->has_blob_readonly ? 1 : 0;
+        break;
      default:
          return -EINVAL;
      }
@@ -453,11 +462,23 @@ static int verify_blob(struct virtio_gpu_device 
*vgdev,
      if (rc_blob->blob_flags & ~VIRTGPU_BLOB_FLAG_USE_MASK)
          return -EINVAL;
+    if (rc_blob->blob_hints & ~VIRTGPU_BLOB_HINT_MASK)
+        return -EINVAL;
+
      if (rc_blob->blob_flags & VIRTGPU_BLOB_FLAG_USE_CROSS_DEVICE) {
          if (!vgdev->has_resource_assign_uuid)
              return -EINVAL;
      }
+    if (rc_blob->blob_flags & VIRTGPU_BLOB_FLAG_USE_READONLY) {
+        if (!vgdev->has_blob_readonly)
+            return -EINVAL;
+    }
+
+    if (rc_blob->userptr &&
+        rc_blob->blob_mem != VIRTGPU_BLOB_MEM_GUEST)
+        return -EINVAL;
+
      switch (rc_blob->blob_mem) {
      case VIRTGPU_BLOB_MEM_GUEST:
          *guest_blob = true;
@@ -495,6 +516,7 @@ static int verify_blob(struct virtio_gpu_device 
*vgdev,
      params->blob = true;
      params->blob_flags = rc_blob->blob_flags;
      params->blob_hints = rc_blob->blob_hints;
+    params->userptr = rc_blob->userptr;
      if (vgdev->has_blob_alignment &&
          !IS_ALIGNED(params->size, vgdev->blob_alignment))
@@ -518,9 +540,10 @@ static int 
virtio_gpu_resource_create_blob_ioctl(struct drm_device *dev,
      struct virtio_gpu_fpriv *vfpriv = file->driver_priv;
      struct drm_virtgpu_resource_create_blob *rc_blob = data;
-    if (verify_blob(vgdev, vfpriv, &params, rc_blob,
-            &guest_blob, &host3d_blob))
-        return -EINVAL;
+    ret = verify_blob(vgdev, vfpriv, &params, rc_blob,
+              &guest_blob, &host3d_blob);
+    if (ret)
+        return ret;
      if (vgdev->has_virgl_3d)
          virtio_gpu_create_context(dev, file);
@@ -538,7 +561,9 @@ static int 
virtio_gpu_resource_create_blob_ioctl(struct drm_device *dev,
                        vfpriv->ctx_id, NULL, NULL);
      }
-    if (guest_blob)
+    if (guest_blob && params.userptr)
+        ret = virtio_gpu_userptr_create(vgdev, file, &params, &bo);
+    else if (guest_blob)
          ret = virtio_gpu_object_create(vgdev, &params, &bo, NULL);
      else if (!guest_blob && host3d_blob)
          ret = virtio_gpu_vram_create(vgdev, &params, &bo);
diff --git a/drivers/gpu/drm/virtio/virtgpu_kms.c b/drivers/gpu/drm/ 
virtio/virtgpu_kms.c
index 1d4d3bf46a..06c2bded49 100644
--- a/drivers/gpu/drm/virtio/virtgpu_kms.c
+++ b/drivers/gpu/drm/virtio/virtgpu_kms.c
@@ -249,15 +249,19 @@ int virtio_gpu_init(struct virtio_device *vdev, 
struct drm_device *dev)
          vgdev->blob_alignment = blob_alignment;
      }
+    if (virtio_has_feature(vgdev->vdev, VIRTIO_GPU_F_BLOB_READONLY))

This hits BUG(). It queries queries VIRTIO_GPU_F_BLOB_READONLY, but the 
feature is absent from the driver’s features[]. virtio_has_feature() 
validates device-specific queries through 
virtio_check_driver_offered_feature(), which executes BUG() for an 
unregistered feature. This affects ordinary probe regardless of host 
support.

Please add the feature to the array and ensure that the patch is 
properly tested before submission.

Really thanks for the point out, we did test in previous version patch,
but for passing AI review I have to added the VIRTIO_GPU_F_BLOB_READONLY 
before send out, the AI review are so many, to address it I made many 
changes, resulted in this issue being overlooked. And I have tested the 
V9, the guest boot is OK, basic function is ok.

And due to the changing for virtio gpu, many other components need to be 
changed, need some times to give qemu/virglrender... code. We have a
lot of parallel tasks here. But I will keep changing code until you are 
satisfied.

Regards,
Honglei



Regards,
Akihiko Odaki

+        vgdev->has_blob_readonly = true;
+
      DRM_INFO("features: %cvirgl %cedid %cresource_blob %chost_visible",
           vgdev->has_virgl_3d    ? '+' : '-',
           vgdev->has_edid        ? '+' : '-',
           vgdev->has_resource_blob ? '+' : '-',
           vgdev->has_host_visible ? '+' : '-');
-    DRM_INFO("features: %ccontext_init %cblob_alignment\n",
+    DRM_INFO("features: %ccontext_init %cblob_alignment 
%cblob_readonly\n",
           vgdev->has_context_init ? '+' : '-',
-         vgdev->has_blob_alignment ? '+' : '-');
+         vgdev->has_blob_alignment ? '+' : '-',
+         vgdev->has_blob_readonly ? '+' : '-');
      ret = virtio_gpu_find_vqs(vgdev);
      if (ret) {