VirtIO devices now remember which endianness they're operating in in order
to support targets which may have guests of either endianness, such as
powerpc. This endianness state is transferred in a subsection of the
virtio device's information.
With virtio-rng this can lead to an abort after a loadvm hitting the
assert() in virtio_is_big_endian(). This can be reproduced by doing a
migrate and load from file on a bi-endian target with a virtio-rng device.
The actual guest state isn't particularly important to triggering this.
The cause is that virtio_rng_load_device() calls virtio_rng_process() which
accesses the ring and thus needs the endianness. However,
virtio_rng_process() is called via virtio_load() before it loads the
subsections. Essentially the ->load callback in VirtioDeviceClass should
only be used for actually reading the device state from the stream, not for
post-load re-initialization.
This patch fixes the bug by moving the virtio_rng_process() after the call
to virtio_load(). Better yet would be to convert virtio to use vmsd and
have the virtio_rng_process() as a post_load callback, but that's a bigger
project for another day.
This is bugfix, and should be considered for the 2.2 branch.
Signed-off-by: David Gibson <da...@gibson.dropbear.id.au>
---
hw/virtio/virtio-rng.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c
index e85a979..473c044 100644
--- a/hw/virtio/virtio-rng.c
+++ b/hw/virtio/virtio-rng.c
@@ -113,20 +113,22 @@ static void virtio_rng_save(QEMUFile *f, void *opaque)
static int virtio_rng_load(QEMUFile *f, void *opaque, int version_id)
{
+ VirtIORNG *vrng = opaque;
+ int ret;
+
if (version_id != 1) {
return -EINVAL;
}
- return virtio_load(VIRTIO_DEVICE(opaque), f, version_id);
-}
+ ret = virtio_load(VIRTIO_DEVICE(vrng), f, version_id);
+ if (ret != 0) {
+ return ret;
+ }
-static int virtio_rng_load_device(VirtIODevice *vdev, QEMUFile *f,
- int version_id)
-{
/* We may have an element ready but couldn't process it due to a quota
* limit. Make sure to try again after live migration when the quota may
* have been reset.
*/
- virtio_rng_process(VIRTIO_RNG(vdev));
+ virtio_rng_process(vrng);
return 0;
}
@@ -231,7 +233,6 @@ static void virtio_rng_class_init(ObjectClass *klass, void
*data)
vdc->realize = virtio_rng_device_realize;
vdc->unrealize = virtio_rng_device_unrealize;
vdc->get_features = get_features;
- vdc->load = virtio_rng_load_device;
}
static void virtio_rng_initfn(Object *obj)
--
1.9.3
