Re: [PATCH v4 09/12] drm/virtio: rework virtio_gpu_object_create fencing

[Chia-I Wu]

On Wed, Jun 19, 2019 at 11:07 PM Gerd Hoffmann <kraxel@xxxxxxxxxx> wrote:
>
> Use gem reservation helpers and direct reservation_object_* calls
> instead of ttm.
>
> v3: Due to using the gem reservation object it is initialized and ready
> for use before calling ttm_bo_init, so we can also drop the tricky fence
> logic which checks whenever the command is in flight still.  We can
> simply fence our object before submitting the virtio command and be done
> with it.
>
> Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
> Acked-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
> ---
>  drivers/gpu/drm/virtio/virtgpu_drv.h    |  6 ++-
>  drivers/gpu/drm/virtio/virtgpu_object.c | 54 +++++++++----------------
>  drivers/gpu/drm/virtio/virtgpu_vq.c     |  8 +++-
>  3 files changed, 30 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
> index 65f5ce41c341..5213d7f499eb 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_drv.h
> +++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
> @@ -267,7 +267,8 @@ void virtio_gpu_free_vbufs(struct virtio_gpu_device *vgdev);
>  void virtio_gpu_cmd_create_resource(struct virtio_gpu_device *vgdev,
>                                     struct virtio_gpu_object *bo,
>                                     struct virtio_gpu_object_params *params,
> -                                   struct virtio_gpu_fence *fence);
> +                                   struct virtio_gpu_fence *fence,
> +                                   struct virtio_gpu_object_array *objs);
Move objs before fence?
>  void virtio_gpu_cmd_unref_resource(struct virtio_gpu_device *vgdev,
>                                    uint32_t resource_id);
>  void virtio_gpu_cmd_transfer_to_host_2d(struct virtio_gpu_device *vgdev,
> @@ -328,7 +329,8 @@ void
>  virtio_gpu_cmd_resource_create_3d(struct virtio_gpu_device *vgdev,
>                                   struct virtio_gpu_object *bo,
>                                   struct virtio_gpu_object_params *params,
> -                                 struct virtio_gpu_fence *fence);
> +                                 struct virtio_gpu_fence *fence,
> +                                 struct virtio_gpu_object_array *objs);
>  void virtio_gpu_ctrl_ack(struct virtqueue *vq);
>  void virtio_gpu_cursor_ack(struct virtqueue *vq);
>  void virtio_gpu_fence_ack(struct virtqueue *vq);
> diff --git a/drivers/gpu/drm/virtio/virtgpu_object.c b/drivers/gpu/drm/virtio/virtgpu_object.c
> index 82bfbf983fd2..90642907aa5c 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_object.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_object.c
> @@ -97,6 +97,7 @@ int virtio_gpu_object_create(struct virtio_gpu_device *vgdev,
>                              struct virtio_gpu_object **bo_ptr,
>                              struct virtio_gpu_fence *fence)
>  {
> +       struct virtio_gpu_object_array *objs = NULL;
>         struct virtio_gpu_object *bo;
>         size_t acc_size;
>         int ret;
> @@ -123,10 +124,27 @@ int virtio_gpu_object_create(struct virtio_gpu_device *vgdev,
>         }
>         bo->dumb = params->dumb;
>
> +       if (fence) {
> +               struct ww_acquire_ctx ticket;
> +
> +               objs = virtio_gpu_array_alloc(1);
> +               objs->objs[0] = &bo->gem_base;
> +               drm_gem_object_get(objs->objs[0]);
> +
> +               ret = drm_gem_lock_reservations(objs->objs, objs->nents,
> +                                               &ticket);
With only one object, we should be able to do a quick
reservation_object_lock_interruptible.
> +               if (ret == 0)
> +                       reservation_object_add_excl_fence(objs->objs[0]->resv,
> +                                                         &fence->f);
> +               drm_gem_unlock_reservations(objs->objs, objs->nents, &ticket);
These may need to be moved to after virtio_gpu_cmd_resource_create_3d.
> +       }
> +
>         if (params->virgl) {
> -               virtio_gpu_cmd_resource_create_3d(vgdev, bo, params, fence);
> +               virtio_gpu_cmd_resource_create_3d(vgdev, bo, params,
> +                                                 fence, objs);
>         } else {
> -               virtio_gpu_cmd_create_resource(vgdev, bo, params, fence);
> +               virtio_gpu_cmd_create_resource(vgdev, bo, params,
> +                                              fence, objs);
>         }
>
>         virtio_gpu_init_ttm_placement(bo);
> @@ -139,38 +157,6 @@ int virtio_gpu_object_create(struct virtio_gpu_device *vgdev,
>         if (ret != 0)
>                 return ret;
>
> -       if (fence) {
> -               struct virtio_gpu_fence_driver *drv = &vgdev->fence_drv;
> -               struct list_head validate_list;
> -               struct ttm_validate_buffer mainbuf;
> -               struct ww_acquire_ctx ticket;
> -               unsigned long irq_flags;
> -               bool signaled;
> -
> -               INIT_LIST_HEAD(&validate_list);
> -               memset(&mainbuf, 0, sizeof(struct ttm_validate_buffer));
> -
> -               /* use a gem reference since unref list undoes them */
> -               drm_gem_object_get(&bo->gem_base);
> -               mainbuf.bo = &bo->tbo;
> -               list_add(&mainbuf.head, &validate_list);
> -
> -               ret = virtio_gpu_object_list_validate(&ticket, &validate_list);
> -               if (ret == 0) {
> -                       spin_lock_irqsave(&drv->lock, irq_flags);
> -                       signaled = virtio_fence_signaled(&fence->f);
> -                       if (!signaled)
> -                               /* virtio create command still in flight */
> -                               ttm_eu_fence_buffer_objects(&ticket, &validate_list,
> -                                                           &fence->f);
> -                       spin_unlock_irqrestore(&drv->lock, irq_flags);
> -                       if (signaled)
> -                               /* virtio create command finished */
> -                               ttm_eu_backoff_reservation(&ticket, &validate_list);
> -               }
> -               virtio_gpu_unref_list(&validate_list);
> -       }
> -
>         *bo_ptr = bo;
>         return 0;
>  }
> diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
> index dc2c2c003200..6e2b287a7e4b 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_vq.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
> @@ -391,13 +391,15 @@ static int virtio_gpu_queue_cursor(struct virtio_gpu_device *vgdev,
>  void virtio_gpu_cmd_create_resource(struct virtio_gpu_device *vgdev,
>                                     struct virtio_gpu_object *bo,
>                                     struct virtio_gpu_object_params *params,
> -                                   struct virtio_gpu_fence *fence)
> +                                   struct virtio_gpu_fence *fence,
> +                                   struct virtio_gpu_object_array *objs)
>  {
>         struct virtio_gpu_resource_create_2d *cmd_p;
>         struct virtio_gpu_vbuffer *vbuf;
>
>         cmd_p = virtio_gpu_alloc_cmd(vgdev, &vbuf, sizeof(*cmd_p));
>         memset(cmd_p, 0, sizeof(*cmd_p));
> +       vbuf->objs = objs;
>
>         cmd_p->hdr.type = cpu_to_le32(VIRTIO_GPU_CMD_RESOURCE_CREATE_2D);
>         cmd_p->resource_id = cpu_to_le32(bo->hw_res_handle);
> @@ -864,13 +866,15 @@ void
>  virtio_gpu_cmd_resource_create_3d(struct virtio_gpu_device *vgdev,
>                                   struct virtio_gpu_object *bo,
>                                   struct virtio_gpu_object_params *params,
> -                                 struct virtio_gpu_fence *fence)
> +                                 struct virtio_gpu_fence *fence,
> +                                 struct virtio_gpu_object_array *objs)
>  {
>         struct virtio_gpu_resource_create_3d *cmd_p;
>         struct virtio_gpu_vbuffer *vbuf;
>
>         cmd_p = virtio_gpu_alloc_cmd(vgdev, &vbuf, sizeof(*cmd_p));
>         memset(cmd_p, 0, sizeof(*cmd_p));
> +       vbuf->objs = objs;
>
>         cmd_p->hdr.type = cpu_to_le32(VIRTIO_GPU_CMD_RESOURCE_CREATE_3D);
>         cmd_p->resource_id = cpu_to_le32(bo->hw_res_handle);
> --
> 2.18.1
>
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