The virtio code uses int, unsigned int, and uint16_t for virtqueue
indices.  The uint16_t is used for the low-level descriptor layout in
virtio_ring.h while code that isn't concerned with descriptor layout can
use unsigned int.

Use of int is problematic because it can result in signed/unsigned
comparison and incompatible int*/unsigned int* pointer types.

Make the virtqueue_get_avail_bytes() 'i' variable unsigned int.  This
eliminates the need to introduce casts and modify code further in the
patches that follow.

Signed-off-by: Stefan Hajnoczi <>
Reviewed-by: Cornelia Huck <>
 hw/virtio/virtio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 10c2f3d..973d0c2 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -416,7 +416,7 @@ void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int 
         unsigned int max, num_bufs, indirect = 0;
         VRingDesc desc;
         hwaddr desc_pa;
-        int i;
+        unsigned int i;
         max = vq->vring.num;
         num_bufs = total_bufs;

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