Re: [RFC 1/7] drm/amdgpu: UAPI for user queue management

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

Am 23.12.22 um 20:36 schrieb Shashank Sharma:
> From: Alex Deucher <alexander.deucher@amd.com>
>
> This patch intorduces new UAPI/IOCTL for usermode graphics
> queue. The userspace app will fill this structure and request
> the graphics driver to add a graphics work queue for it. The
> output of this UAPI is a queue id.
>
> This UAPI maps the queue into GPU, so the graphics app can start
> submitting work to the queue as soon as the call returns.
>
> Cc: Alex Deucher <alexander.deucher@amd.com>
> Cc: Christian Koenig <christian.koenig@amd.com>
> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
> Signed-off-by: Shashank Sharma <shashank.sharma@amd.com>
> ---
>   include/uapi/drm/amdgpu_drm.h | 52 +++++++++++++++++++++++++++++++++++
>   1 file changed, 52 insertions(+)
>
> diff --git a/include/uapi/drm/amdgpu_drm.h b/include/uapi/drm/amdgpu_drm.h
> index 0d93ec132ebb..a3d0dd6f62c5 100644
> --- a/include/uapi/drm/amdgpu_drm.h
> +++ b/include/uapi/drm/amdgpu_drm.h
> @@ -54,6 +54,7 @@ extern "C" {
>   #define DRM_AMDGPU_VM			0x13
>   #define DRM_AMDGPU_FENCE_TO_HANDLE	0x14
>   #define DRM_AMDGPU_SCHED		0x15
> +#define DRM_AMDGPU_USERQ		0x16
>   
>   #define DRM_IOCTL_AMDGPU_GEM_CREATE	DRM_IOWR(DRM_COMMAND_BASE + DRM_AMDGPU_GEM_CREATE, union drm_amdgpu_gem_create)
>   #define DRM_IOCTL_AMDGPU_GEM_MMAP	DRM_IOWR(DRM_COMMAND_BASE + DRM_AMDGPU_GEM_MMAP, union drm_amdgpu_gem_mmap)
> @@ -71,6 +72,7 @@ extern "C" {
>   #define DRM_IOCTL_AMDGPU_VM		DRM_IOWR(DRM_COMMAND_BASE + DRM_AMDGPU_VM, union drm_amdgpu_vm)
>   #define DRM_IOCTL_AMDGPU_FENCE_TO_HANDLE DRM_IOWR(DRM_COMMAND_BASE + DRM_AMDGPU_FENCE_TO_HANDLE, union drm_amdgpu_fence_to_handle)
>   #define DRM_IOCTL_AMDGPU_SCHED		DRM_IOW(DRM_COMMAND_BASE + DRM_AMDGPU_SCHED, union drm_amdgpu_sched)
> +#define DRM_IOCTL_AMDGPU_USERQ		DRM_IOW(DRM_COMMAND_BASE + DRM_AMDGPU_USERQ, union drm_amdgpu_userq)
>   
>   /**
>    * DOC: memory domains
> @@ -288,6 +290,56 @@ union drm_amdgpu_ctx {
>   	union drm_amdgpu_ctx_out out;
>   };
>   
> +/* user queue IOCTL */
> +#define AMDGPU_USERQ_OP_CREATE	1
> +#define AMDGPU_USERQ_OP_FREE	2
> +
> +#define AMDGPU_USERQ_MQD_FLAGS_SECURE	(1 << 0)
> +#define AMDGPU_USERQ_MQD_FLAGS_AQL	(1 << 1)
> +
> +struct drm_amdgpu_userq_mqd {
> +	/** Flags: AMDGPU_USERQ_MQD_FLAGS_* */
> +	__u32	flags;
> +	/** IP type: AMDGPU_HW_IP_* */
> +	__u32	ip_type;
> +	/** GEM object handle */
> +	__u32   doorbell_handle;
> +	/** Doorbell offset in dwords */
> +	__u32   doorbell_offset;
> +	/** GPU virtual address of the queue */
> +	__u64   queue_va;
> +	/** Size of the queue in bytes */
> +	__u64   queue_size;
> +	/** GPU virtual address of the rptr */
> +	__u64   rptr_va;
> +	/** GPU virtual address of the wptr */
> +	__u64   wptr_va;

We should probably note somewhere that those are inputs to the queue and 
need to be allocated by userspace somewhere.

> +};
> +
> +struct drm_amdgpu_userq_in {
> +	/** AMDGPU_USERQ_OP_* */
> +	__u32	op;
> +	/** Flags */
> +	__u32	flags;

> +	/** Context handle to associate the queue with */
> +	__u32	ctx_id;

Uff, this is just blunt nonsense. Queues are not related to ctx objects 
in any way possible.

> +	__u32	pad;
> +	/** Queue descriptor */
> +	struct drm_amdgpu_userq_mqd mqd;
> +};
> +
> +struct drm_amdgpu_userq_out {
> +	/** Queue handle */
> +	__u32	q_id;
> +	/** Flags */
> +	__u32	flags;
> +};
> +
> +union drm_amdgpu_userq {
> +	struct drm_amdgpu_userq_in in;
> +	struct drm_amdgpu_userq_out out;
> +};
> +
>   /* vm ioctl */
>   #define AMDGPU_VM_OP_RESERVE_VMID	1
>   #define AMDGPU_VM_OP_UNRESERVE_VMID	2