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

[Huang, Honglei1]

On 2025/2/3 16:25, Akihiko Odaki wrote:
> On 2024/12/20 19:04, Honglei Huang wrote:
> > From: Honglei Huang <Honglei1.Huang@xxxxxxx>
> >
> > 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@xxxxxxx>
> > ---
> >   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;
Hi Akihiko,

Really thanks for the information, I think maybe using an unused number 
is a better way. I will send a patch to virtio-spec to occupy a unused one.

Regards,
Honglei