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 <david@gibson.dropbear.id.au>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 05f0a80..9e95ca6 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -234,11 +234,14 @@
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)