** Description changed: ## Bug ## There are conditions where old qemu/libvirt created guests with the osxsafe or ospke cpu feature: <feature policy='require' name='osxsave'/> <feature policy='require' name='ospke'/> That feature was removed in recent qemu, this triggers issues starting some old guests definitions using it after upgrade. qemu-system-x86_64: can't apply global Broadwell-noTSX-x86_64- cpu.osxsave=on: Property '.osxsave' not found Same bug in Fedora (incomplete) [5] for being non reproducible - probably didn't see the new virt-install avoiding (but not fixing) it. ## What happened ## Both commandline arg drops "osxsave" / "ospke" were effective no-ops as it was - quote: "never configurable: KVM never returned OSXSAVE on GET_SUPPORTED_CPUID". See removal commits [1][2]. Discussions went on if this should be warnings instead of errors for a while (the deprecation discussion is ongoing anyway). But for now we are in the situation that calling qemu with those features makes it fail to start. I'd not want to derive from upstream qemu and the discussion on depreceation - as mentioned - is a longer one that won't resolve too soon - a.k.a we can't wait on that. The discussion at [3] reached no conclusion and was forgotten. I checked with Jiri and there was no follow on. But since specifying the features never meant anything to qemu we should at least consider libvirt to learn about that and just not specify the flags. If there is a good place for a warning we might emit one if required was set, but this is not strictly required at first. ## when does it trigger => severity ## Comment 14 [4] adds more details, we checked usage through virsh, python-livbirt (uvtool, multipass, openstack) and virt-install. We only found two cases in virt-install either: - created the guest in the past --cpu=host-model This guest will fail to start on upgrade - pre virt-install 2.0 (not a Ubuntu combo) it would also break with e.g. virt-install 1.5 and qemu 3.1 with --cpu=host-copy => Both options were not even documented anymore back n Xenial, but they are kept for compatibility. Overall - unless we missed a more important use case - this is ugly but not show-stopping in prio. To further enforce this not being a common case, if you'd have set required you'd have got the following all along: - error: the CPU is incompatible with host CPU: - Host CPU does not provide required features: ospke + error: the CPU is incompatible with host CPU: + Host CPU does not provide required features: ospke This is due to the features rarely (never?) exists in the host. - But if set to off or optional (which becomes off if the host doesn't have it) then you'd have seen the new issue. + But if set to off or optional (which becomes off if the host doesn't have it) then you'd have seen the new issue. The same applies to "disable" which would pass the pre-check but then let new qemu fail. Obviously it also triggers if: - libvirt XML with added <feature policy='optional' name='osxsave'/> - virt-install with --cpu ...,+osxsave / ospke ## Workaround until resolved ## Per the analysis above it hopefully should only affect a very low number of people with very old virtual machines anyway, but if you are affected you want a way out and that is fair. For now just remove that features: $ virsh edit <guestname> # remove lines like these <feature policy='optional' name='osxsave'/> <feature policy='optional' name='ospke'/> + Or the same with disable instead of optional. Now your guest will start again. --- [1]: https://git.qemu.org/?p=qemu.git;a=commit;h=f1a23522b03a569f13aad49294bb4c4b1a9500c7 [2]: https://git.qemu.org/?p=qemu.git;a=commit;h=9ccb9784b57804f5c74434ad6ccb66650a015ffc [3]: https://www.mail-archive.com/qemu-devel@nongnu.org/msg561877.html [4]: https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1825195/comments/14 [5]: https://bugzilla.redhat.com/show_bug.cgi?id=1644848
** Description changed: ## Bug ## There are conditions where old qemu/libvirt created guests with the osxsafe or ospke cpu feature: - <feature policy='require' name='osxsave'/> - <feature policy='require' name='ospke'/> + <feature policy='disable' name='osxsave'/> + <feature policy='optional' name='ospke'/> That feature was removed in recent qemu, this triggers issues starting some old guests definitions using it after upgrade. qemu-system-x86_64: can't apply global Broadwell-noTSX-x86_64- cpu.osxsave=on: Property '.osxsave' not found Same bug in Fedora (incomplete) [5] for being non reproducible - probably didn't see the new virt-install avoiding (but not fixing) it. ## What happened ## Both commandline arg drops "osxsave" / "ospke" were effective no-ops as it was - quote: "never configurable: KVM never returned OSXSAVE on GET_SUPPORTED_CPUID". See removal commits [1][2]. Discussions went on if this should be warnings instead of errors for a while (the deprecation discussion is ongoing anyway). But for now we are in the situation that calling qemu with those features makes it fail to start. I'd not want to derive from upstream qemu and the discussion on depreceation - as mentioned - is a longer one that won't resolve too soon - a.k.a we can't wait on that. The discussion at [3] reached no conclusion and was forgotten. I checked with Jiri and there was no follow on. But since specifying the features never meant anything to qemu we should at least consider libvirt to learn about that and just not specify the flags. If there is a good place for a warning we might emit one if required was set, but this is not strictly required at first. ## when does it trigger => severity ## Comment 14 [4] adds more details, we checked usage through virsh, python-livbirt (uvtool, multipass, openstack) and virt-install. We only found two cases in virt-install either: - created the guest in the past --cpu=host-model This guest will fail to start on upgrade - pre virt-install 2.0 (not a Ubuntu combo) it would also break with e.g. virt-install 1.5 and qemu 3.1 with --cpu=host-copy => Both options were not even documented anymore back n Xenial, but they are kept for compatibility. Overall - unless we missed a more important use case - this is ugly but not show-stopping in prio. To further enforce this not being a common case, if you'd have set required you'd have got the following all along: error: the CPU is incompatible with host CPU: Host CPU does not provide required features: ospke This is due to the features rarely (never?) exists in the host. But if set to off or optional (which becomes off if the host doesn't have it) then you'd have seen the new issue. The same applies to "disable" which would pass the pre-check but then let new qemu fail. Obviously it also triggers if: - libvirt XML with added <feature policy='optional' name='osxsave'/> - virt-install with --cpu ...,+osxsave / ospke ## Workaround until resolved ## Per the analysis above it hopefully should only affect a very low number of people with very old virtual machines anyway, but if you are affected you want a way out and that is fair. For now just remove that features: $ virsh edit <guestname> # remove lines like these <feature policy='optional' name='osxsave'/> <feature policy='optional' name='ospke'/> Or the same with disable instead of optional. Now your guest will start again. --- [1]: https://git.qemu.org/?p=qemu.git;a=commit;h=f1a23522b03a569f13aad49294bb4c4b1a9500c7 [2]: https://git.qemu.org/?p=qemu.git;a=commit;h=9ccb9784b57804f5c74434ad6ccb66650a015ffc [3]: https://www.mail-archive.com/qemu-devel@nongnu.org/msg561877.html [4]: https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1825195/comments/14 [5]: https://bugzilla.redhat.com/show_bug.cgi?id=1644848 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1825195 Title: qemu dropped osxsave/ospke feature triggering upgrade issues To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1825195/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
