Commit 70d1ace5 authored by Gurchetan Singh's avatar Gurchetan Singh Committed by Dmitry Osipenko
Browse files

drm/virtio: Conditionally allocate virtio_gpu_fence 



We don't want to create a fence for every command submission.  It's
only necessary when userspace provides a waitable token for submission.
This could be:

1) bo_handles, to be used with VIRTGPU_WAIT
2) out_fence_fd, to be used with dma_fence apis
3) a ring_idx provided with VIRTGPU_CONTEXT_PARAM_POLL_RINGS_MASK
   + DRM event API
4) syncobjs in the future

The use case for just submitting a command to the host, and expecting
no response.  For example, gfxstream has GFXSTREAM_CONTEXT_PING that
just wakes up the host side worker threads.  There's also
CROSS_DOMAIN_CMD_SEND which just sends data to the Wayland server.

This prevents the need to signal the automatically created
virtio_gpu_fence.

In addition, VIRTGPU_EXECBUF_RING_IDX is checked when creating a
DRM event object.  VIRTGPU_CONTEXT_PARAM_POLL_RINGS_MASK is
already defined in terms of per-context rings.  It was theoretically
possible to create a DRM event on the global timeline (ring_idx == 0),
if the context enabled DRM event polling.  However, that wouldn't
work and userspace (Sommelier).  Explicitly disallow it for
clarity.

Signed-off-by: default avatarGurchetan Singh <gurchetansingh@chromium.org>
Reviewed-by: default avatarDmitry Osipenko <dmitry.osipenko@collabora.com>
Tested-by: default avatarDmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com> # edited coding style
Link: https://patchwork.freedesktop.org/patch/msgid/20230707213124.494-1-gurchetansingh@chromium.org
parent 8d1077cf

drivers/gpu/drm/virtio/virtgpu_submit.c

+20 −12
Original line number Diff line number Diff line
@@ -64,13 +64,9 @@ static int virtio_gpu_fence_event_create(struct drm_device *dev, 
					 struct virtio_gpu_fence *fence,

					 u32 ring_idx)

{

	struct virtio_gpu_fpriv *vfpriv = file->driver_priv;

	struct virtio_gpu_fence_event *e = NULL;

	int ret;



	if (!(vfpriv->ring_idx_mask & BIT_ULL(ring_idx)))

		return 0;



	e = kzalloc(sizeof(*e), GFP_KERNEL);

	if (!e)

		return -ENOMEM;
@@ -164,19 +160,31 @@ static int virtio_gpu_init_submit(struct virtio_gpu_submit *submit, 
	struct virtio_gpu_fpriv *vfpriv = file->driver_priv;

	struct virtio_gpu_device *vgdev = dev->dev_private;

	struct virtio_gpu_fence *out_fence;

	bool drm_fence_event;

	int err;



	memset(submit, 0, sizeof(*submit));



	if ((exbuf->flags & VIRTGPU_EXECBUF_RING_IDX) &&

	    (vfpriv->ring_idx_mask & BIT_ULL(ring_idx)))

		drm_fence_event = true;

	else

		drm_fence_event = false;



	if ((exbuf->flags & VIRTGPU_EXECBUF_FENCE_FD_OUT) ||

	    exbuf->num_bo_handles ||

	    drm_fence_event)

		out_fence = virtio_gpu_fence_alloc(vgdev, fence_ctx, ring_idx);

	if (!out_fence)

		return -ENOMEM;

	else

		out_fence = NULL;



	if (drm_fence_event) {

		err = virtio_gpu_fence_event_create(dev, file, out_fence, ring_idx);

		if (err) {

			dma_fence_put(&out_fence->f);

			return err;

		}

	}



	submit->out_fence = out_fence;

	submit->fence_ctx = fence_ctx;