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). Stefan
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