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    Subject[PATCH 2/3] 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 <>
    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;
    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)

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      Last update: 2012-04-12 07:39    [W:0.041 / U:0.820 seconds]
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