Re: [PATCH v4 03/10] drm/amdgpu: add new IOCTL for usermode queue

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

Am 24.04.23 um 19:38 schrieb Shashank Sharma:
> This patch adds:
> - A new IOCTL function to create and destroy
> - A new structure to keep all the user queue data in one place.
> - A function to generate unique index for the queue.
>
> V1: Worked on review comments from RFC patch series:
>    - Alex: Keep a list of queues, instead of single queue per process.
>    - Christian: Use the queue manager instead of global ptrs,
>             Don't keep the queue structure in amdgpu_ctx
>
> V2: Worked on review comments:
>   - Christian:
>     - Formatting of text
>     - There is no need for queuing of userqueues, with idr in place
>   - Alex:
>     - Remove use_doorbell, its unnecessary
>     - Reuse amdgpu_mqd_props for saving mqd fields
>
>   - Code formatting and re-arrangement
>
> V3:
>   - Integration with doorbell manager
>
> V4:
>   - Accommodate MQD union related changes in UAPI (Alex)
>   - Do not set the queue size twice (Bas)
>
> Cc: Alex Deucher <alexander.deucher@amd.com>
> Cc: Christian Koenig <christian.koenig@amd.com>
> Signed-off-by: Shashank Sharma <shashank.sharma@amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c       |   1 +
>   drivers/gpu/drm/amd/amdgpu/amdgpu_userqueue.c | 126 ++++++++++++++++++
>   .../gpu/drm/amd/include/amdgpu_userqueue.h    |   2 +
>   3 files changed, 129 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> index 2d6bcfd727c8..229976a2d0e7 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> @@ -2749,6 +2749,7 @@ const struct drm_ioctl_desc amdgpu_ioctls_kms[] = {
>   	DRM_IOCTL_DEF_DRV(AMDGPU_GEM_VA, amdgpu_gem_va_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
>   	DRM_IOCTL_DEF_DRV(AMDGPU_GEM_OP, amdgpu_gem_op_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
>   	DRM_IOCTL_DEF_DRV(AMDGPU_GEM_USERPTR, amdgpu_gem_userptr_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
> +	DRM_IOCTL_DEF_DRV(AMDGPU_USERQ, amdgpu_userq_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
>   };
>   
>   static const struct drm_driver amdgpu_kms_driver = {
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userqueue.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_userqueue.c
> index effc0c7c02cf..333f31efbe7b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userqueue.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userqueue.c
> @@ -23,6 +23,132 @@
>    */
>   
>   #include "amdgpu.h"
> +#include "amdgpu_vm.h"
> +#include "amdgpu_userqueue.h"
> +
> +static inline int
> +amdgpu_userqueue_index(struct amdgpu_userq_mgr *uq_mgr, struct amdgpu_usermode_queue *queue)

Maybe call that handle instead of index. And I don't think you actually 
need those wrapper functions, see below.

> +{
> +	return idr_alloc(&uq_mgr->userq_idr, queue, 1, AMDGPU_MAX_USERQ, GFP_KERNEL);
> +}
> +
> +static inline void
> +amdgpu_userqueue_free_index(struct amdgpu_userq_mgr *uq_mgr, int queue_id)
> +{
> +	idr_remove(&uq_mgr->userq_idr, queue_id);
> +}
> +
> +static struct amdgpu_usermode_queue *
> +amdgpu_userqueue_find(struct amdgpu_userq_mgr *uq_mgr, int qid)
> +{
> +	return idr_find(&uq_mgr->userq_idr, qid);
> +}
> +
> +static int amdgpu_userqueue_create_gfx(struct drm_file *filp, union drm_amdgpu_userq *args)
> +{
> +	struct amdgpu_usermode_queue *queue;
> +	struct amdgpu_fpriv *fpriv = filp->driver_priv;
> +	struct amdgpu_userq_mgr *uq_mgr = &fpriv->userq_mgr;
> +	struct drm_amdgpu_userq_mqd_gfx *mqd_in = &args->in.mqd.gfx;
> +	int r;
> +
> +	/* Do we support usermode queues on this GFX IP ? */
> +	if (!uq_mgr->userq_funcs[AMDGPU_HW_IP_GFX]) {
> +		DRM_ERROR("Usermode queue is not supported for this GFX IP\n");
> +		return -EINVAL;
> +	}
> +
> +	queue = kzalloc(sizeof(struct amdgpu_usermode_queue), GFP_KERNEL);
> +	if (!queue) {
> +		DRM_ERROR("Failed to allocate memory for queue\n");
> +		return -ENOMEM;
> +	}
> +
> +	mutex_lock(&uq_mgr->userq_mutex);
> +	queue->userq_prop.wptr_gpu_addr = mqd_in->wptr_va;
> +	queue->userq_prop.rptr_gpu_addr = mqd_in->rptr_va;
> +	queue->userq_prop.queue_size = mqd_in->queue_size;
> +	queue->userq_prop.hqd_base_gpu_addr = mqd_in->queue_va;
> +
> +	queue->doorbell_handle = mqd_in->doorbell_handle;
> +	queue->queue_type = AMDGPU_HW_IP_GFX;
> +	queue->flags = mqd_in->flags;
> +	queue->vm = &fpriv->vm;
> +	queue->queue_id = amdgpu_userqueue_index(uq_mgr, queue);

It is usually good practice to *not* store those handles inside the 
object they refer to, background is that this always creates a circle 
reference (handle->object, object->handle).

Additional to that I would move registering the userspace handle out of 
this function.

> +	if (queue->queue_id < 0) {
> +		DRM_ERROR("Failed to allocate a queue id\n");
> +		r = queue->queue_id;
> +		goto free_queue;
> +	}
> +
> +	args->out.queue_id = queue->queue_id;
> +	args->out.flags = 0;
> +	mutex_unlock(&uq_mgr->userq_mutex);
> +	return 0;
> +
> +free_queue:
> +	mutex_unlock(&uq_mgr->userq_mutex);
> +	kfree(queue);
> +	return r;
> +}
> +
> +static int amdgpu_userqueue_create(struct drm_file *filp, union drm_amdgpu_userq *args)
> +{
> +	u32 ip_type = args->in.ip_type;
> +
> +	switch (ip_type) {
> +	case AMDGPU_HW_IP_GFX:
> +		return amdgpu_userqueue_create_gfx(filp, args);
> +	default:
> +		DRM_ERROR("Usermode queue is not supported for this IP (%u)\n", ip_type);
> +	}

Instead insert the idr_alloc() or more generally handle alloc here.

Christian.

> +
> +	return -EINVAL;
> +}
> +
> +static void amdgpu_userqueue_destroy(struct drm_file *filp, int queue_id)
> +{
> +	struct amdgpu_fpriv *fpriv = filp->driver_priv;
> +	struct amdgpu_userq_mgr *uq_mgr = &fpriv->userq_mgr;
> +	struct amdgpu_usermode_queue *queue;
> +
> +	queue = amdgpu_userqueue_find(uq_mgr, queue_id);
> +	if (!queue) {
> +		DRM_DEBUG_DRIVER("Invalid queue id to destroy\n");
> +		return;
> +	}
> +
> +	mutex_lock(&uq_mgr->userq_mutex);
> +	amdgpu_userqueue_free_index(uq_mgr, queue->queue_id);
> +	mutex_unlock(&uq_mgr->userq_mutex);
> +	kfree(queue);
> +}
> +
> +int amdgpu_userq_ioctl(struct drm_device *dev, void *data,
> +		       struct drm_file *filp)
> +{
> +	union drm_amdgpu_userq *args = data;
> +	int r = 0;
> +
> +	switch (args->in.op) {
> +	case AMDGPU_USERQ_OP_CREATE:
> +		r = amdgpu_userqueue_create(filp, args);
> +		if (r)
> +			DRM_ERROR("Failed to create usermode queue\n");
> +		break;
> +
> +	case AMDGPU_USERQ_OP_FREE:
> +		amdgpu_userqueue_destroy(filp, args->in.queue_id);
> +		break;
> +
> +	default:
> +		DRM_ERROR("Invalid user queue op specified: %d\n", args->in.op);
> +		return -EINVAL;
> +	}
> +
> +	return r;
> +}
> +
>   
>   int amdgpu_userq_mgr_init(struct amdgpu_userq_mgr *userq_mgr, struct amdgpu_device *adev)
>   {
> diff --git a/drivers/gpu/drm/amd/include/amdgpu_userqueue.h b/drivers/gpu/drm/amd/include/amdgpu_userqueue.h
> index 6fe5d8d73f37..8d8f6b3bcda5 100644
> --- a/drivers/gpu/drm/amd/include/amdgpu_userqueue.h
> +++ b/drivers/gpu/drm/amd/include/amdgpu_userqueue.h
> @@ -43,6 +43,8 @@ struct amdgpu_userq_funcs {
>   	void (*mqd_destroy)(struct amdgpu_userq_mgr *uq_mgr, struct amdgpu_usermode_queue *uq);
>   };
>   
> +int amdgpu_userq_ioctl(struct drm_device *dev, void *data, struct drm_file *filp);
> +
>   int amdgpu_userq_mgr_init(struct amdgpu_userq_mgr *userq_mgr, struct amdgpu_device *adev);
>   
>   void amdgpu_userq_mgr_fini(struct amdgpu_userq_mgr *userq_mgr);