Re: [PATCH 05/10] drm/amdgpu: add AMDGPU_INFO_SDMA_USERQ_DOORBELL ioctl

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

On 4/24/26 10:18, Jesse Zhang wrote:
> From: "Jesse.zhang" <Jesse.zhang@amd.com>
> 
> New AMDGPU_INFO query that returns a per-fpriv GEM handle for the
> kernel-owned BO backing the SDMA UMQ doorbell window, plus its size.
> Userspace mmap()s that handle through the standard
> AMDGPU_GEM_OP_MMAP / mmap() flow to obtain a CPU pointer to the
> routable doorbell BAR window; each created SDMA usermode queue's
> qword-slot offset inside that mapping is reported in
> drm_amdgpu_userq_out.sdma_doorbell_offset_bytes.

We added the separate IOCTL for this purpose on the KFD/KGD unification branch. I think we should just cherry pick that over to amd-staging-drm-next.

@Alex what do you think?

Regards,
Christian.

> 
> Signed-off-by: Jesse Zhang <Jesse.Zhang@amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c | 13 +++++++++++++
>  include/uapi/drm/amdgpu_drm.h           | 16 ++++++++++++++++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
> index d88e4994c8c1..dbcfbe418e42 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
> @@ -1425,6 +1425,19 @@ int amdgpu_info_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
>  			return -EINVAL;
>  		}
>  	}
> +	case AMDGPU_INFO_SDMA_USERQ_DOORBELL: {
> +		struct drm_amdgpu_info_sdma_userq_doorbell db_info = {};
> +		int r;
> +
> +		r = amdgpu_sdma_userq_doorbell_create_handle(adev, filp,
> +							     &db_info.handle,
> +							     &db_info.size_bytes);
> +		if (r)
> +			return r;
> +		return copy_to_user(out, &db_info,
> +				    min((size_t)size, sizeof(db_info)))
> +			? -EFAULT : 0;
> +	}
>  	default:
>  		DRM_DEBUG_KMS("Invalid request %d\n", info->query);
>  		return -EINVAL;
> diff --git a/include/uapi/drm/amdgpu_drm.h b/include/uapi/drm/amdgpu_drm.h
> index 79e8bbda046b..533be8ad8a7e 100644
> --- a/include/uapi/drm/amdgpu_drm.h
> +++ b/include/uapi/drm/amdgpu_drm.h
> @@ -1280,6 +1280,22 @@ struct drm_amdgpu_cs_chunk_cp_gfx_shadow {
>  #define AMDGPU_INFO_GPUVM_FAULT			0x23
>  /* query FW object size and alignment */
>  #define AMDGPU_INFO_UQ_FW_AREAS			0x24
> +/*
> + * SDMA usermode-queue doorbell window query.  Returns a per-fpriv GEM
> + * handle for a kernel-owned BO that backs the routable SDMA doorbell
> + * window, plus its byte size.  Userspace mmap()s the BO via the standard
> + * AMDGPU_GEM_OP_MMAP / mmap() flow to get a CPU pointer; each created
> + * SDMA usermode queue's slot offset inside that mapping is returned in
> + * drm_amdgpu_userq_out.sdma_doorbell_offset_bytes.
> + */
> +#define AMDGPU_INFO_SDMA_USERQ_DOORBELL		0x25
> +
> +struct drm_amdgpu_info_sdma_userq_doorbell {
> +	/* Per-fpriv GEM handle for the SDMA UMQ doorbell BO. */
> +	__u32 handle;
> +	/* Byte size of the BO (== mmappable window size). */
> +	__u32 size_bytes;
> +};
>  
>  #define AMDGPU_INFO_MMR_SE_INDEX_SHIFT	0
>  #define AMDGPU_INFO_MMR_SE_INDEX_MASK	0xff