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-rw-r--r--hw/virtio/virtio.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 933a3d749a..8357218ae6 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -93,7 +93,7 @@ struct VirtQueue
 
     uint16_t queue_index;
 
-    int inuse;
+    unsigned int inuse;
 
     uint16_t vector;
     VirtIOHandleOutput handle_output;
@@ -1878,9 +1878,11 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f, int version_id)
             /*
              * Some devices migrate VirtQueueElements that have been popped
              * from the avail ring but not yet returned to the used ring.
+             * Since max ring size < UINT16_MAX it's safe to use modulo
+             * UINT16_MAX + 1 subtraction.
              */
-            vdev->vq[i].inuse = vdev->vq[i].last_avail_idx -
-                                vdev->vq[i].used_idx;
+            vdev->vq[i].inuse = (uint16_t)(vdev->vq[i].last_avail_idx -
+                                vdev->vq[i].used_idx);
             if (vdev->vq[i].inuse > vdev->vq[i].vring.num) {
                 error_report("VQ %d size 0x%x < last_avail_idx 0x%x - "
                              "used_idx 0x%x",