[PATCH] drm/virtio: Support drm_panic with non-vmapped shmem BO

[Dmitry Osipenko]

On 4/12/25 16:20, Ryosuke Yasuoka wrote:
> Pass array of pages of the scanout buffer [1] to shmem BO, allowing
> drm_panic to work even if the BO is not vmapped.
> 
> [1] https://lore.kernel.org/all/20250407140138.162383-3-jfalempe@redhat.com/
> 
> Signed-off-by: Jocelyn Falempe <jfalempe at redhat.com>
> Signed-off-by: Ryosuke Yasuoka <ryasuoka at redhat.com>
> ---
>  drivers/gpu/drm/virtio/virtgpu_plane.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/virtio/virtgpu_plane.c b/drivers/gpu/drm/virtio/virtgpu_plane.c
> index a6f5a78f436a..2ff57d559c86 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_plane.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_plane.c
> @@ -500,11 +500,19 @@ static int virtio_drm_get_scanout_buffer(struct drm_plane *plane,
>  
>  	bo = gem_to_virtio_gpu_obj(plane->state->fb->obj[0]);
>  
> -	/* Only support mapped shmem bo */
> -	if (virtio_gpu_is_vram(bo) || bo->base.base.import_attach || !bo->base.vaddr)
> +	if (virtio_gpu_is_vram(bo) || bo->base.base.import_attach)
>  		return -ENODEV;
>  
> -	iosys_map_set_vaddr(&sb->map[0], bo->base.vaddr);
> +	if (bo->base.vaddr)
> +		iosys_map_set_vaddr(&sb->map[0], bo->base.vaddr);
> +	else {
> +		struct drm_gem_shmem_object *shmem = &bo->base;
> +
> +		if (!shmem->pages)
> +			return -ENODEV;
> +		/* map scanout buffer later */
> +		sb->pages = shmem->pages;
> +	}
>  
>  	sb->format = plane->state->fb->format;
>  	sb->height = plane->state->fb->height;
> 
> base-commit: e7bb7d44c3b97aea1f0e354c6499900154ac67f2

Works well!

Reviewed-by: Dmitry Osipenko <dmitry.osipenko at collabora.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko at collabora.com>

-- 
Best regards,
Dmitry