On Tue, Jun 09, 2020 at 05:47:47PM +0200, Claudio Imbrenda wrote: > On Tue, 9 Jun 2020 11:41:30 +0200 > Halil Pasic <pa...@linux.ibm.com> wrote: > > [...] > > > I don't know. Janosch could answer that, but he is on vacation. Adding > > Claudio maybe he can answer. My understanding is, that while it might > > be possible, it is ugly at best. The ability to do a transition is > > indicated by a CPU model feature. Indicating the feature to the guest > > and then failing the transition sounds wrong to me. > > I agree. If the feature is advertised, then it has to work. I don't > think we even have an architected way to fail the transition for that > reason.
So my suggestion was basically a flag that sets both the CPU model feature and the virtio feature. > What __could__ be done is to prevent qemu from even starting if an > incompatible device is specified together with PV. > > Another option is to disable PV at the qemu level if an incompatible > device is present. This will have the effect that trying to boot a > secure guest will fail mysteriously, which is IMHO also not too great. > > do we really have that many incompatible devices? >
