Hi all,
we recently encountered the problem that the 'host-model' [1] has to be related to the machine type of a domain. We have following problem:
Let's assume we've a z13 system with a QEMU 2.9 and we define a domain using the default s390-virtio-ccw machine together with the host-model CPU mode [1]. The definition will have the machine expanded to s390-virtio-ccw-2.9 but retain the host-model CPU mode in the domain definition. In a next step we upgrade to QEMU 2.10 (first version to recognize z14). Everything is still fine, even though the machine runs in 2.9 compatibility mode. Finally we upgrade to a z14. As a consequence it is not possible to start the domain anymore as the machine type doesn't support our CPU host model (which is expanded at start time of the domain).
Actually, what is the cause of that problem? I assume it is the gs feature (gs_allowed)? We should really avoid such things (..._allowed) for CPU model features in the future and clue all new such stuff to cpumodel_allowed. -- Thanks, David