On 27 November 2014 at 09:26, Markus Armbruster <arm...@redhat.com> wrote: > David Gibson <da...@gibson.dropbear.id.au> writes: > >> 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. > > "[PATCH for-2.2]" would have been a good idea then. Next time :)
So do you want this patch in 2.2? I was planning to put in the virtio-vs-xen fixes today and tag rc4, so it's not too late if you're confident this patch is good. Let me know if you think it should go in, and I can apply it to master directly. -- PMM