If the virtio device supports indirect ring descriptors we need only one
ring entry for the whole command. Take that into account when checking
whenever the virtqueue has enough free entries for our command.
Signed-off-by: Gerd Hoffmann <[email protected]>
---
drivers/gpu/drm/virtio/virtgpu_vq.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
index 41e475fbd67b..a2ec09dba530 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -328,7 +328,8 @@ static void virtio_gpu_queue_ctrl_sgs(struct virtio_gpu_device *vgdev,
{
struct virtqueue *vq = vgdev->ctrlq.vq;
bool notify = false;
- int ret;
+ bool indirect;
+ int vqcnt, ret;
again:
spin_lock(&vgdev->ctrlq.qlock);
@@ -341,9 +342,11 @@ static void virtio_gpu_queue_ctrl_sgs(struct virtio_gpu_device *vgdev,
return;
}
- if (vq->num_free < elemcnt) {
+ indirect = virtio_has_feature(vgdev->vdev, VIRTIO_RING_F_INDIRECT_DESC);
+ vqcnt = indirect ? 1 : elemcnt;
+ if (vq->num_free < vqcnt) {
spin_unlock(&vgdev->ctrlq.qlock);
- wait_event(vgdev->ctrlq.ack_queue, vq->num_free >= elemcnt);
+ wait_event(vgdev->ctrlq.ack_queue, vq->num_free >= vqcnt);
goto again;
}
--
2.18.1
On Thu, Feb 6, 2020 at 3:14 AM Gerd Hoffmann <[email protected]> wrote:
>
> If the virtio device supports indirect ring descriptors we need only one
> ring entry for the whole command. Take that into account when checking
> whenever the virtqueue has enough free entries for our command.
>
> Signed-off-by: Gerd Hoffmann <[email protected]>
> ---
> drivers/gpu/drm/virtio/virtgpu_vq.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
> index 41e475fbd67b..a2ec09dba530 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_vq.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
> @@ -328,7 +328,8 @@ static void virtio_gpu_queue_ctrl_sgs(struct virtio_gpu_device *vgdev,
> {
> struct virtqueue *vq = vgdev->ctrlq.vq;
> bool notify = false;
> - int ret;
> + bool indirect;
> + int vqcnt, ret;
>
> again:
> spin_lock(&vgdev->ctrlq.qlock);
> @@ -341,9 +342,11 @@ static void virtio_gpu_queue_ctrl_sgs(struct virtio_gpu_device *vgdev,
> return;
> }
>
> - if (vq->num_free < elemcnt) {
> + indirect = virtio_has_feature(vgdev->vdev, VIRTIO_RING_F_INDIRECT_DESC);
> + vqcnt = indirect ? 1 : elemcnt;
Is the feature dynamic and require the lock held? If not, the result
can be cached and the fixup can happen before grabbing the lock
if (vgdev->has_indirect_desc)
elemcnt = 1;
Either way, patch is
Reviewed-by: Chia-I Wu <[email protected]>
> + if (vq->num_free < vqcnt) {
> spin_unlock(&vgdev->ctrlq.qlock);
> - wait_event(vgdev->ctrlq.ack_queue, vq->num_free >= elemcnt);
> + wait_event(vgdev->ctrlq.ack_queue, vq->num_free >= vqcnt);
> goto again;
> }
>
> --
> 2.18.1
>
Hi,
> > + indirect = virtio_has_feature(vgdev->vdev, VIRTIO_RING_F_INDIRECT_DESC);
> > + vqcnt = indirect ? 1 : elemcnt;
> Is the feature dynamic and require the lock held? If not, the result
> can be cached and the fixup can happen before grabbing the lock
Not dynamic, so yes, caching makes sense.
cheers,
Gerd