diff options
| author | Michael S. Tsirkin <mst@redhat.com> | 2009-10-25 15:28:53 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-11-09 16:22:28 -0800 |
| commit | 48fe10afb355d88be5a9c0b7d5a198c5e5b9b4aa (patch) | |
| tree | 2c5a5cd8ca0d0e0821b31177883bf727f85be0d6 /drivers | |
| parent | bed202356361d3620a51974eadca78261e049ef0 (diff) | |
virtio: order used ring after used index read
commit 2d61ba95034f1abbdec7729d52c740870a5eddb6 upstream.
On SMP guests, reads from the ring might bypass used index reads. This
causes guest crashes because host writes to used index to signal ring
data readiness. Fix this by inserting rmb before used ring reads.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/virtio/virtio_ring.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index a882f2606515..0ffff9ed4eb0 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -281,6 +281,9 @@ static void *vring_get_buf(struct virtqueue *_vq, unsigned int *len) return NULL; } + /* Only get used array entries after they have been exposed by host. */ + rmb(); + i = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].id; *len = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].len; |