4.4-stable review patch. If anyone has any objections, please let me know.
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From: Gerd Hoffmann kraxel@redhat.com
commit d02d270014f70dcab0117776b81a37b6fca745ae upstream.
Wait until we have enough space in the virt queue to actually queue up our request. Avoids the guest spinning in case we have a non-zero amount of free entries but not enough for the request.
Cc: stable@vger.kernel.org Reported-by: Alain Magloire amagloire@blackberry.com Signed-off-by: Gerd Hoffmann kraxel@redhat.com Reviewed-by: Dave Airlie airlied@redhat.com Link: http://patchwork.freedesktop.org/patch/msgid/20180403095904.11152-1-kraxel@r... Signed-off-by: Sean Paul seanpaul@chromium.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/gpu/drm/virtio/virtgpu_vq.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c @@ -324,7 +324,7 @@ retry: ret = virtqueue_add_sgs(vq, sgs, outcnt, incnt, vbuf, GFP_ATOMIC); if (ret == -ENOSPC) { spin_unlock(&vgdev->ctrlq.qlock); - wait_event(vgdev->ctrlq.ack_queue, vq->num_free); + wait_event(vgdev->ctrlq.ack_queue, vq->num_free >= outcnt + incnt); spin_lock(&vgdev->ctrlq.qlock); goto retry; } else { @@ -399,7 +399,7 @@ retry: ret = virtqueue_add_sgs(vq, sgs, outcnt, 0, vbuf, GFP_ATOMIC); if (ret == -ENOSPC) { spin_unlock(&vgdev->cursorq.qlock); - wait_event(vgdev->cursorq.ack_queue, vq->num_free); + wait_event(vgdev->cursorq.ack_queue, vq->num_free >= outcnt); spin_lock(&vgdev->cursorq.qlock); goto retry; } else {