From c0ed8ece4ef395e8b1665fdba276b7285c44f0ab Mon Sep 17 00:00:00 2001 From: Gerd Hoffmann Date: Tue, 3 Apr 2018 11:59:04 +0200 Subject: [PATCH] drm/virtio: fix vq wait_event condition 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 Signed-off-by: Gerd Hoffmann Reviewed-by: Dave Airlie Link: http://patchwork.freedesktop.org/patch/msgid/20180403095904.11152-1-kraxel@redhat.com Signed-off-by: Sean Paul Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/virtio/virtgpu_vq.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c index 9eb96fb2c147..26a2da1f712d 100644 --- a/drivers/gpu/drm/virtio/virtgpu_vq.c +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c @@ -291,7 +291,7 @@ static int virtio_gpu_queue_ctrl_buffer_locked(struct virtio_gpu_device *vgdev, 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 { @@ -366,7 +366,7 @@ static int virtio_gpu_queue_cursor(struct virtio_gpu_device *vgdev, 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 {