Re: [RFC PATCH 1/3] virtio-gpu api: add blob userptr resource

[Akihiko Odaki <akihiko.odaki@daynix.com>]

On 2024/12/20 19:04, Honglei Huang wrote:
> From: Honglei Huang <Honglei1.Huang@amd.com>
> 
> Add a new resource for blob resource, called userptr, used for let
> host access guest user space memory, to acquire a simple SVM features
> in virtio GPU.
> 
> - The capset VIRTIO_GPU_CAPSET_HSAKMT used for context init,
> in this series patches only HSAKMT context can use the userptr
> feature. HSAKMT is a GPU compute library in HSA stack, like
> the role libdrm in mesa stack.
> - New flag VIRTIO_GPU_BLOB_FLAG_USE_USERPTR used in blob create
> to indicate the blob create ioctl is used for create a userptr
> blob resource.
> 
> Signed-off-by: Honglei Huang <Honglei1.Huang@amd.com>
> ---
>   include/uapi/linux/virtio_gpu.h | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/include/uapi/linux/virtio_gpu.h b/include/uapi/linux/virtio_gpu.h
> index b9a9783f0b14..0a6b56acbc13 100644
> --- a/include/uapi/linux/virtio_gpu.h
> +++ b/include/uapi/linux/virtio_gpu.h
> @@ -323,6 +323,7 @@ struct virtio_gpu_cmd_submit {
>   
>   #define VIRTIO_GPU_CAPSET_VIRGL 1
>   #define VIRTIO_GPU_CAPSET_VIRGL2 2
> +#define VIRTIO_GPU_CAPSET_HSAKMT 7

The changes to add VIRTIO_GPU_CAPSET_VENUS and VIRTIO_GPU_CAPSET_DRM are 
already merged so this should be rebased for clean apply.

Number 7 is also occupied since 2023:
https://chromium.googlesource.com/crosvm/crosvm/+/e4c1878733937042111fca58899a3a94002bfef0%5E%21/rutabaga_gfx/src/rutabaga_utils.rs

VCL, a proposed VirtIO-GPU OpenCL driver, is also going to use that number:
https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31634/diffs?commit_id=55a1a8a32057e83819b046f2de03aca333b052b4

I think you should talk with Antonio Caggiano, who picked the number for 
VCL, to allocate a number without a conflict with VCL.

Gurchetan (the author of Rutabaga change allocating the number), I think 
you should notify the number usage by sending a patch for Linux or 
virtio-spec.

Regards,
Akihiko Odaki

>   
>   /* VIRTIO_GPU_CMD_GET_CAPSET_INFO */
>   struct virtio_gpu_get_capset_info {
> @@ -415,6 +416,7 @@ struct virtio_gpu_resource_create_blob {
>   #define VIRTIO_GPU_BLOB_FLAG_USE_MAPPABLE     0x0001
>   #define VIRTIO_GPU_BLOB_FLAG_USE_SHAREABLE    0x0002
>   #define VIRTIO_GPU_BLOB_FLAG_USE_CROSS_DEVICE 0x0004
> +#define VIRTIO_GPU_BLOB_FLAG_USE_USERPTR      0x0008
>   	/* zero is invalid blob mem */
>   	__le32 blob_mem;
>   	__le32 blob_flags;