Re: [PATCH 2/3] virtio_balloon: Fix endian bug
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2012-04-12 08:30:47
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On Thu, Apr 12, 2012 at 03:36:34PM +1000, David Gibson wrote:
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 <redacted>
Indeed. And qemu byte-swaps according to the spec, too. Applied for 3.4, thanks.
quoted hunk
--- drivers/virtio/virtio_balloon.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 6c07793..553cc1f 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c@@ -238,11 +238,14 @@ 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)-- 1.7.9.5