Re: [PATCH] drm/virtio: Don't detach GEM from a non-created context

[Dmitry Osipenko <dmitry.osipenko@collabora.com>]

Hi,

On 6/25/26 20:08, Jason Macnak wrote:
> Applies the same treatment as commit 7cf6dd467e87 ("drm/virtio:
> Don't attach GEM to a non-created context in gem_object_open()")
> to virtio_gpu_gem_object_close() to avoid trying to detach
> a resource that was never attached due to a context
> never being created when context_init is supported.
> 
> Fixes: 086b9f27f0ab ("drm/virtio: Don't create a context with default param if context_init is supported")
> Cc: <stable@vger.kernel.org> # v6.14+
> Signed-off-by: Jason Macnak <natsu@google.com>
> ---
>  drivers/gpu/drm/virtio/virtgpu_gem.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/virtio/virtgpu_gem.c b/drivers/gpu/drm/virtio/virtgpu_gem.c
> index 435d37d36034..66c3f6f74e9c 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_gem.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_gem.c
> @@ -139,13 +139,15 @@ void virtio_gpu_gem_object_close(struct drm_gem_object *obj,
>  	if (!vgdev->has_virgl_3d)
>  		return;
>  
> -	objs = virtio_gpu_array_alloc(1);
> -	if (!objs)
> -		return;
> -	virtio_gpu_array_add_obj(objs, obj);
> +	if (vfpriv->context_created) {
> +		objs = virtio_gpu_array_alloc(1);
> +		if (!objs)
> +			return;
> +		virtio_gpu_array_add_obj(objs, obj);
>  
> -	virtio_gpu_cmd_context_detach_resource(vgdev, vfpriv->ctx_id,
> -					       objs);
> +		virtio_gpu_cmd_context_detach_resource(vgdev, vfpriv->ctx_id,
> +						       objs);
> +	}
>  	virtio_gpu_notify(vgdev);
>  }

The following scenario still will be troubling:

1. vgdev->has_context_init = true
2. virtio_gpu_gem_object_open() invoked, GEM created and not attached to ctx
3. virtio_gpu_context_init_ioctl() invoked, now vfpriv->context_created
= true
4. virtio_gpu_gem_object_close() will detach resource that wasn't attached

Add obj->ctx_attached member to struct virtio_gpu_object. See
virtio_gpu_object_attach() that uses obj->attached, do the same for
virtio_gpu_cmd_context_attach_resource().

-- 
Best regards,
Dmitry