Re: [PATCH v2 0/5] s390x: CPU Topology

[Pierre Morel]

On 8/30/21 11:54 AM, Christian Borntraeger wrote:
> On 26.08.21 11:22, Pierre Morel wrote:
> > a gentle ping :)
> >
> > I would like if you have time, comments on the architecture I propose,
> > if the handling is done at the right level, KVM vs QEMU.
>
> Do we expect changes in this series due to the discussed changes of PTF 
> interpretion?

No we do not expect any change.
The configuration topology feature is enabled in QEMU if KVM provides 
the KVM_CAP_S390_CPU_TOPOLOGY.

Interpretation is set in KVM if QEMU activated the feature and if the 
host supports the configuration topology feature.

If the host does not support the feature, interception is done and QEMU 
emulates the PTF instruction.

The feature can be fenced with qemu -cpu XX,ctop=off for CPU already 
having the feature activated as default in QEMU (newer GEN10_GA1)


Regards,
Pierre


--
Pierre Morel
IBM Lab Boeblingen