Re: [PATCH 3/3] drm/virtio: Implement device_attach

["Christian König" <christian.koenig@amd.com>]

Am 07.12.24 um 11:50 schrieb Julia Zhang:
> As vram objects may be imported by other gpu drivers, peer2peer flag
> should be checked in dma_buf_ops->attach(). This reimplement virtio gpu
> dma_buf_ops->attach by adding a device_attach() function for virtio gpu.
> This function will get pci_p2pdma_distance and check attach->peer2peer
> before calling drm_gem_map_attach().
>
> Signed-off-by: Julia Zhang <julia.zhang@amd.com>

I can't judge that virtgpu or XEN code path, but that here looks like it 
should work.

Acked-by: Christian König <christian.koenig@amd.com>

> ---
>   drivers/gpu/drm/virtio/virtgpu_prime.c | 14 +++++++++++++-
>   1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/virtio/virtgpu_prime.c b/drivers/gpu/drm/virtio/virtgpu_prime.c
> index 4960620eba02..4f6bce79e10e 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_prime.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_prime.c
> @@ -116,6 +116,18 @@ static int virtgpu_get_p2pdma_distance(struct dma_buf *dma_buf,
>   	return 0;
>   }
>   
> +static int virtgpu_gem_device_attach(struct dma_buf *dma_buf,
> +				     struct dma_buf_attachment *attach)
> +{
> +	int ret = virtgpu_get_p2pdma_distance(dma_buf, attach);
> +	if (ret)
> +		return ret;
> +	if (!attach->peer2peer)
> +		return -EBUSY;
> +
> +	return drm_gem_map_attach(dma_buf, attach);
> +}
> +
>   static const struct virtio_dma_buf_ops virtgpu_dmabuf_ops =  {
>   	.ops = {
>   		.cache_sgt_mapping = true,
> @@ -128,7 +140,7 @@ static const struct virtio_dma_buf_ops virtgpu_dmabuf_ops =  {
>   		.vmap = drm_gem_dmabuf_vmap,
>   		.vunmap = drm_gem_dmabuf_vunmap,
>   	},
> -	.device_attach = drm_gem_map_attach,
> +	.device_attach = virtgpu_gem_device_attach,
>   	.get_uuid = virtgpu_virtio_get_uuid,
>   };
>