Re: [Qemu-devel] [PATCH v2] s390x/cpumodel: model PTFF subfunctions for Multiple-epoch facility

[Cornelia Huck <cohuck@redhat.com>]

On Mon, 5 Feb 2018 12:27:33 +0100
David Hildenbrand <david@redhat.com> wrote:

> On 05.02.2018 12:22, Christian Borntraeger wrote:
> > Looks sane on a z14.
> > Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
> > 
> > 
> > On 02/05/2018 11:29 AM, David Hildenbrand wrote:  
> >> --- a/target/s390x/kvm.c
> >> +++ b/target/s390x/kvm.c
> >> @@ -2221,6 +2221,14 @@ void kvm_s390_get_host_cpu_model(S390CPUModel *model, Error **errp)
> >>          return;
> >>      }
> >>
> >> +    /* PTFF subfunctions might be indicated although kernel support missing */
> >> +    if (!test_bit(S390_FEAT_MULTIPLE_EPOCH, model->features)) {
> >> +        clear_bit(S390_FEAT_PTFF_QSIE, model->features);
> >> +        clear_bit(S390_FEAT_PTFF_QTOUE, model->features);
> >> +        clear_bit(S390_FEAT_PTFF_STOE, model->features);
> >> +        clear_bit(S390_FEAT_PTFF_STOUE, model->features);
> >> +    }
> >> +
> >>      /* with cpu model support, CMM is only indicated if really available */
> >>      if (kvm_s390_cmma_available()) {
> >>          set_bit(S390_FEAT_CMM, model->features);
> >>  
> > 
> > Do you also want to add something to check_consistency ?
> > 
> > Right now the following user error 
> > -cpu z14,mepoch=off,mepochptff=on
> > is accepted.
> > On the other hand we also have no consistency checks for other subfunctions.
> >   
> 
> Thought about that, but that implies that a CPU model runable now, will
> not run without warnings. Especially if migrating. We could add such
> checks if we would push this into stable.
> 

So, adding this check for the z14 stuff would work iff pushed into
stable - but for the other subfunctions the ship has already sailed?