On Mon, Mar 30, 2015 at 07:37:12PM +0200, Michael S. Tsirkin wrote:
> Virtio 1.0 doesn't include a modern balloon device.
> But it's not a big change to support a transitional
> balloon device: this has the advantage of supporting
> existing drivers, transparently.
>
> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> ---
Hmm, re-reading the code, this won't be enough for BE
guests. We are doing one extra byteswap there.
I'll fix up and repost.
> include/uapi/linux/virtio_balloon.h | 6 ++++++
> drivers/virtio/virtio_balloon.c | 8 ++++++--
> 2 files changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h
> index 4b0488f..5d83902 100644
> --- a/include/uapi/linux/virtio_balloon.h
> +++ b/include/uapi/linux/virtio_balloon.h
> @@ -56,4 +56,10 @@ struct virtio_balloon_stat {
> __u64 val;
> } __attribute__((packed));
>
> +struct virtio_balloon_stat_modern {
> + __u8 reserved[6];
> + __u16 tag;
> + __u64 val;
> +};
> +
> #endif /* _LINUX_VIRTIO_BALLOON_H */
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 6a356e3..68e937f 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -77,7 +77,7 @@ struct virtio_balloon {
>
> /* Memory statistics */
> int need_stats_update;
> - struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR];
> + struct virtio_balloon_stat_modern stats[VIRTIO_BALLOON_S_NR];
>
> /* To register callback in oom notifier call chain */
> struct notifier_block nb;
> @@ -269,7 +269,11 @@ static void stats_handle_request(struct virtio_balloon *vb)
> vq = vb->stats_vq;
> if (!virtqueue_get_buf(vq, &len))
> return;
> - sg_init_one(&sg, vb->stats, sizeof(vb->stats));
> + if (virtio_has_feature(vdev, VIRTIO_F_VERSION_1))
> + sg_init_one(&sg, vb->stats, sizeof(vb->stats));
> + else
> + sg_init_one(&sg, &vb->stats->tag, sizeof(vb->stats) -
> + offsetof(typeof(*vb->stats, tag);
> virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
> virtqueue_kick(vq);
> }
> --
> MST
>
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