From: Gurchetan Singh gurchetansingh@chromium.org

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: Gurchetan Singh gurchetansingh@chromium.org Reviewed-by: Dmitry Osipenko dmitry.osipenko@collabora.com Tested-by: Dmitry 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-gurchetan... (cherry picked from commit 70d1ace56db6c79d39dbe9c0d5244452b67e2fde) Signed-off-by: Alyssa Ross hi@alyssa.is --- drivers/gpu/drm/virtio/virtgpu_submit.c | 30 ++++++++++++++++--------- 1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_submit.c b/drivers/gpu/drm/virtio/virtgpu_submit.c index cf3c04b16a7a..1d010c66910d 100644 --- a/drivers/gpu/drm/virtio/virtgpu_submit.c +++ b/drivers/gpu/drm/virtio/virtgpu_submit.c @@ -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; @@ -164,18 +160,30 @@ 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));

- out_fence = virtio_gpu_fence_alloc(vgdev, fence_ctx, ring_idx); - if (!out_fence) - return -ENOMEM; + if ((exbuf->flags & VIRTGPU_EXECBUF_RING_IDX) && + (vfpriv->ring_idx_mask & BIT_ULL(ring_idx))) + drm_fence_event = true; + else + drm_fence_event = false;

- err = virtio_gpu_fence_event_create(dev, file, out_fence, ring_idx); - if (err) { - dma_fence_put(&out_fence->f); - return err; + 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); + 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;

base-commit: 3766ec12cf894667026786fef355bb998c263f03