[PATCH v1] virtio: stregthen virtqueue size invariants

[Denis Plotnikov]

1. virtqueue_size is a power of 2
2. virtqueue_size > 2, since seg_max is virtqueue_size - 2

Signed-off-by: Denis Plotnikov <address@hidden>
---
 hw/virtio/virtio.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 04716b5f6c..e3ab69061e 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -2166,7 +2166,8 @@ void virtio_queue_set_num(VirtIODevice *vdev, int n, int 
num)
      */
     if (!!num != !!vdev->vq[n].vring.num ||
         num > VIRTQUEUE_MAX_SIZE ||
-        num < 0) {
+        num < 2 ||
+        !is_power_of_2(num)) {
         return;
     }
     vdev->vq[n].vring.num = num;
-- 
2.17.0