* Christian Borntraeger (borntrae...@de.ibm.com) wrote: > On 02/16/2017 03:51 PM, Janosch Frank wrote: > > While trying to fix a bug in the s390 migration code, I noticed that > > QEMU ignores practically all errors returned from that VM ioctl. QEMU > > behaves as specified in the KVM api and only processes -1 (-EPERM) as an > > error. > > > > Unfortunately the documentation is wrong/old and KVM may return -EFAULT, > > -EINVAL, -ENOTSUPP (BookE) and -ENOENT. This bugs me, as I found a case > > where I want to return -EFAULT because of guest memory problems and QEMU > > will still happily migrate the VM. > > > > I currently don't see a reason why we continue to migrate on EFAULT and > > EINVAL. But returning -error from kvm_physical_sync_dirty_bitmap might > > also a bit hard, as it kills QEMU. > > > > Do we want to fix this and if, how do we want it done? > > If not we at least have a definitive mail to point to when the next one > > comes around. I also have a KVM patch to update the api documentation if > > wanted (maybe we should dust that off a bit anyhow). > > I think we want to handle _ALL_ error of that ioctl. Instead of aborting > QEMU we might just want to abort the migration in that case?
Yes, I don't see any reason to kill the source guest. > > This has been brought up in 2009 [1] the first time and was more or less > > fixed and then reverted in 2014 [2]. > > > > The reason in [1] was that PPC hadn't settled yet on a valid return code. > > > > In [2] it was too close to the v2 to handle it properly. > > > > > > [1] https://lists.nongnu.org/archive/html/qemu-devel/2009-07/msg01772.html > > > > [2] https://lists.nongnu.org/archive/html/qemu-devel/2014-04/msg01993.html > > So back then it was just too close to 2.0 and should have been revisited for > 2.1. Lets now fix it for 2.9? Yes Dave > > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
