** Description changed: + [ Impact ] + + libvirt users who attempt to migrate a VM to a Noble host will + experience failures due to missing CPU features, which ultimately + prevents the migration from concluding successfully. This is related to + bug #2051754. + + [ Test Plan ] + + The reporter has a setup ready to reproduce the problem. In theory, all + that is needed to trigger the error is: + + 1) Create LXD VMs. + + 2) Install libvirt inside each one, create a VM inside one, and then try + to migrate it to the other. + + There is also an extensive testsuite covering many migration scenarios + that is used whenever a new libvirt/QEMU is prepared to be uploaded. I + will be running the testsuite against the new libvirt to make sure it + passes all tests. + + [ Where problems could occur ] + + Fortunately the fix is somewhat simple and contained: it's just one + patch (that's already been accepted upstream), which changes a very + specific code path in the virCPUx86UpdateLive function (inside + src/cpu/cpu_x86.c). The problem happens in a very specific scenario + where you're trying to migrate a VM between hosts using a similar + libvirt version; in this case, the first libvirt (where the VM is + created) correctly detects that there are some CPU features missing, but + the second libvirt (where the VM will be migrated to) will fail when it + notices that those same CPU features are not present. + + Patches modifying code in this area have the possibility of messing up + some (obscure?) migration path. We hope to prevent such a regression + from happening by running our migration testsuite (as described in the + Test Plan); it has already caught failures affecting corner cases in the + past. If this proves insufficient, we can revert the changes + temporarily while working with upstream (who has been responsive about + this issue) to improve the existing solution. + + [ Original Description ] + Trying to live migrate between two libvirt daemons 24.04 hosted on fresh LXD VMs is failing virsh migrate --verbose --live demo-server-$host --copy-storage-all qemu+ssh://$other_host/system error: operation failed: guest CPU doesn't match specification: missing features: vmx-apicv-xapic,vmx-apicv-register,vmx-apicv-vid,vmx-vmfunc,vmx-posted-intr,vmx-eptp-switching Libvirt VMs were created with the following commands: virt-install -n demo-server-$host --virt-type=kvm --arch=x86_64 --machine=q35 --description "demo-server migration" --os-variant=ubuntu22.04 --ram=2048 --cpu host-model,topology.sockets=1,topology.cores=2,topology.threads=1 --vcpus=2 --graphics none --cdrom /tmp/jammy-server-cloudimg-amd64.img --network bridge:br0 lsb_release -rd Description: Ubuntu 24.04 LTS Release: 24.04 apt-cache policy libvirt-daemon libvirt-daemon: - Installed: 10.0.0-2ubuntu8.2 + Installed: 10.0.0-2ubuntu8.2 ProblemType: Bug DistroRelease: Ubuntu 24.04 Package: libvirt-daemon 10.0.0-2ubuntu8.2 ProcVersionSignature: Ubuntu 6.8.0-36.36-generic 6.8.4 Uname: Linux 6.8.0-36-generic x86_64 ApportVersion: 2.28.1-0ubuntu3 Architecture: amd64 CasperMD5CheckResult: unknown CloudArchitecture: x86_64 CloudBuildName: server CloudID: lxd CloudName: lxd CloudPlatform: lxd CloudSerial: 20240702 CloudSubPlatform: LXD socket API v. 1.0 (/dev/lxd/sock) Date: Wed Jul 3 18:43:50 2024 ProcEnviron: - LANG=C.UTF-8 - PATH=(custom, no user) - SHELL=/bin/bash - TERM=xterm-256color - XDG_RUNTIME_DIR=<set> + LANG=C.UTF-8 + PATH=(custom, no user) + SHELL=/bin/bash + TERM=xterm-256color + XDG_RUNTIME_DIR=<set> SourcePackage: libvirt UpgradeStatus: No upgrade log present (probably fresh install)
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2071848 Title: live migration fails because of missing cpu features vmx-* To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/2071848/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
