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SubjectRe: [PATCH 2/3] virtio_balloon: Fix endian bug
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 <david@gibson.dropbear.id.au>

Indeed. And qemu byte-swaps according to the spec, too.
Applied for 3.4, thanks.

> ---
> 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


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