virtio_balloon: Fix endian bug

Although virtio config space fields are usually in guest-native endian, the spec for the virtio balloon device explicitly states that both fields in its config space are little-endian. However, the current virtio_balloon driver does not have a suitable endian swap for the 'num_pages' field, although it does have one for the 'actual' field. This patch corrects the bug, adding sparse annotation while we're at it. Signed-off-by: David Gibson <[email protected]> Signed-off-by: Michael S. Tsirkin <[email protected]>
cbmeeks · Apr 15, 2012 · 1a87228 · 1a87228
1 parent c0aa3e0
commit 1a87228
Showing 1 changed file with 5 additions and 2 deletions.
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
@@ -234,11 +234,14 @@ static void virtballoon_changed(struct virtio_device *vdev)
 
 static inline s64 towards_target(struct virtio_balloon *vb)
 {
-	u32 v;
+	__le32 v;
+	s64 target;
+
 	vb->vdev->config->get(vb->vdev,
 			      offsetof(struct virtio_balloon_config, num_pages),
 			      &v, sizeof(v));
-	return (s64)v - vb->num_pages;
+	target = le32_to_cpu(v);
+	return target - vb->num_pages;
 }
 
 static void update_balloon_size(struct virtio_balloon *vb)