Re: [Qemu-devel] [Qemu-stable] [ANNOUNCE] QEMU 2.6.1 Stable released

[Michael Roth <mdroth@linux.vnet.ibm.com>]

Quoting Stefan Hajnoczi (2016-09-05 12:54:35)
> On Fri, Aug 26, 2016 at 01:45:56PM +0200, Peter Lieven wrote:
> > Am 25.08.2016 um 19:23 schrieb Michael Roth:
> > > Quoting Peter Lieven (2016-08-25 01:38:13)
> > > > 7c509d1 virtio: decrement vq->inuse in virtqueue_discard()
> > > > 700f26b virtio: recalculate vq->inuse after migration
> > > Looks like these got posted during the freeze :(
> > > 
> > > > The virtio thing is important because live migration is broken without
> > > > the fix as  86cc089 is in 2.6.1.
> > > Not sure I understand the relation to 86cc089. Wouldn't the check
> > > introduced there always pass due to target initializing inuse to 0?
> > > 
> > > Or is the issue that the fix introduced in 86cc089 is only partially
> > > effective due to inuse not being recalculated properly on target? That might
> > > warrant a 2.6.1.1...
> > 
> > This is what Stefan wrote in the cover letter to the series:
> > 
> > "I should mention this is for QEMU 2.7. These fixes are needed if the
> > CVE-2016-5403 patch has been applied. Without these patches any device that holds VirtQueueElements acros
> > live migration will terminate with a "Virtqueue size exceeded" error message. virtio-balloon and virtio-scsi are affected. virtio-bl
> > probably too but I haven't tested it."
> > 
> > Maybe
> 
> The virtio inuse fixes are needed for stable (v2.6.2?) so that the
> spurious "Virtqueue size exceeded" on migration is solved.
> 
> The error can be reproduced when there is a VirtQueueElement pending
> across migration (e.g. virtio-blk s->rq failed request list).

Thanks for clarifying. I'm planning to do a 2.6.2 to capture these, the
patches Peter mentioned, and some other fixes that came during 2.7 RC
phase.

I have an initial staging tree at:

  https://github.com/mdroth/qemu/commits/stable-2.6-staging

There's still a few PULLs in flight with patches I plan to pull in, but
hoping to send out the patch round-up early next week and a release the
following week.

> 
> Stefan