[PATCH 1/6] virtio_balloon: transitional interface
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2015-03-30 17:37:23
Also in:
lkml, virtualization
Subsystem:
the rest, virtio balloon, virtio core · Maintainers:
Linus Torvalds, "Michael S. Tsirkin", David Hildenbrand, Jason Wang
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@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