[libvirt] Question about the host-model CPU mode

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. The definition will have the machine expanded to s390-virtio-ccw-2.9 but retain the host-model CPU mode. 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). Is this behavior expected? There are some ways to avoid this problem: - CPU model expansion is performed at domain definition time - host-model is related to the machine type of a domain Thank you in advance. Beste Grüße / Kind regards Marc Hartmayer IBM Deutschland Research & Development GmbH Vorsitzende des Aufsichtsrats: Martina Koederitz Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen Registergericht: Amtsgericht Stuttgart, HRB 243294