On Wed, Jun 10, 2020 at 09:22:45AM +0200, David Hildenbrand wrote: > On 10.06.20 06:31, David Gibson wrote: > > On Tue, Jun 09, 2020 at 12:44:39PM -0400, Michael S. Tsirkin wrote: > >> On Tue, Jun 09, 2020 at 06:28:39PM +0200, Halil Pasic wrote: > >>> On Tue, 9 Jun 2020 17:47:47 +0200 > >>> Claudio Imbrenda <imbre...@linux.ibm.com> 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. > >>>> > >>>> What __could__ be done is to prevent qemu from even starting if an > >>>> incompatible device is specified together with PV. > >>> > >>> AFAIU, the "specified together with PV" is the problem here. Currently > >>> we don't "specify PV" but PV is just a capability that is managed by the > >>> CPU model (like so many other). > >> > >> So if we want to keep it user friendly, there could be > >> protection property with values on/off/auto, and auto > >> would poke at host capability to figure out whether > >> it's supported. > >> > >> Both virtio and CPU would inherit from that. > > > > Right, that's what I have in mind for my 'host-trust-limitation' > > property (a generalized version of the existing 'memory-encryption' > > machine option). My draft patches already set virtio properties > > accordingly, it should be possible to set (default) cpu properties as > > well. > > No crazy CPU model hacks please (at least speaking for the s390x).
Uh... I'm not really sure what you have in mind here.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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