Comment 4 for bug 1846501

From a users perspective this can be solved simply by not providing updated libvirt/qemu package in the UCA repositories - the versions provided in Xenial are sufficient to run nova, and are also going to get consistent updates during the lifespan of the release.

If a newer version is really desired then ideally I would suggest it is pulled from the next LTS release up, rather than one from a non LTS release - the version requirements in openstack for functionality don't change that much between releases, so there's plenty of warning, and again patching of security updates is handled by someone else.

Upgrading to Queens is not something that is immediately available to us, and would also require a double bump going via Pike, which I guess may also have its own libvirt/qemu deployments which I fear may have the same bugs. I appreciate that the control plane can be upgraded and use "[upgrade_levels]" to maintain compatability, and the hypervisors could potentially skip Pike (or maintain the held libvirt/qemu packages as I have done for Ocata).

My actual aim is to transition to a kolla based deployment, but the ocata image using Ubuntu binaries has the newer qemu and libvirt packages, and so we will be unable to migrate our hypervisors until a later release anyway with this issue.

Thanks for all the references and input here folks :)