On Fri, Nov 28, 2014 at 09:14:46AM +0000, Peter Maydell wrote: > 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.
Yes, I think it should be applied.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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