(actually adding Greg) On (Thu) 27 Nov 2014 [14:38:42], Amit Shah wrote: > On (Thu) 27 Nov 2014 [16:48:10], David Gibson wrote: > > 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. > > Agreed. > > > 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. > > This is undoing most of 3902d49e13c2428bd6381cfdf183103ca4477c1f , > added Greg to CC list. > > Did you try this on x86 guests, or with multiple rng devices? > > (keeping context for Greg) > > > 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) > > > Thanks, > > Amit
Amit