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 <m...@redhat.com>
---
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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