On 11.03.22 10:17, Daniel P. Berrangé wrote: > On Thu, Mar 10, 2022 at 11:17:38PM -0500, Collin Walling wrote: >> CPU models past gen16a will no longer support the csske feature. In >> order to secure migration of guests running on machines that still >> support this feature to machines that do not, let's disable csske >> in the host-model. Sorry to say, removing CPU features is a no-go when wanting to guarantee forward migration without taking care about CPU model details manually and simply using the host model. Self-made HW vendor problem. > > The problem scenario you describe is the intended semantics of > host-model though. It enables all features available in the host > that you launched on. It lets you live migrate to a target host > with the same, or a greater number of features. If the target has > a greater number of features, it should restrict the VM to the > subset of features that were present on the original source CPU. > If the target has fewer features, then you simply can't live > migrate a VM using host-model. > > To get live migration in both directions across CPUs with differing > featuresets, then the VM needs to be configured with a named CPU > model that is a subset of both, rather than host-model. Right, and cpu-model-baseline does that job for you if you're lazy to lookup the proper model. -- Thanks, David / dhildenb
