On 10/6/26 18:42, Val Packett wrote:
> VIRTIO_GPU_F_BLOB_ALIGNMENT is designed for GPU rendering context types,
> however VIRTIO_GPU_CAPSET_CROSS_DOMAIN is not one of those. Resources
> created under cross-domain contexts are arbitrary shared system memory
> files, which includes unusual things like Wayland keymaps received
> from the host compositor. Do not enforce alignment requirements there.
>
> Fixes: 47248e0d8264 ("drm/virtio: honor blob_alignment requirements")
> Signed-off-by: Val Packett <[email protected]>
> ---
>
> v2: also check has_virgl_3d to prevent dereferencing NULL vfpriv
> v1:
> https://lore.kernel.org/all/[email protected]/
>
> ~val
>
> ---
> drivers/gpu/drm/virtio/virtgpu_ioctl.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> index 3ddd5481d6bc..4d5ae062834d 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
> @@ -551,7 +551,9 @@ static int verify_blob(struct virtio_gpu_device *vgdev,
> params->blob_flags = rc_blob->blob_flags;
> params->blob_hints = rc_blob->blob_hints;
>
> - if (vgdev->has_blob_alignment &&
> + if (vgdev->has_blob_alignment && vgdev->has_virgl_3d &&
> + (vfpriv->context_init & VIRTIO_GPU_CONTEXT_INIT_CAPSET_ID_MASK) !=
> + VIRTIO_GPU_CAPSET_CROSS_DOMAIN &&
> !IS_ALIGNED(params->size, vgdev->blob_alignment))
> return -EINVAL;
>
What userspace has this problem and why it re-purposes virtio-gpu to act
as udmabuf for arbitrary data that never reaches host?
--
Best regards,
Dmitry
