Re: [PATCH v8 1/2] s390x: KVM: guest support for topology function

Claudio Imbrenda
2022-04-20T13:22:56Z

On Wed, 20 Apr 2022 14:05:00 +0200
Heiko Carstens <hca@linux.ibm.com> wrote:

> > +static inline bool kvm_s390_topology_changed(struct kvm_vcpu *vcpu)
> > +{
> > + if (!test_kvm_facility(vcpu->kvm, 11))
> > + return false;
> > +
> > + /* A new vCPU has been hotplugged */
> > + if (vcpu->arch.prev_cpu == S390_KVM_TOPOLOGY_NEW_CPU)
> > + return true;
> > +
> > + /* The real CPU backing up the vCPU moved to another socket */
> > + if (cpumask_test_cpu(vcpu->cpu,
> > + topology_core_cpumask(vcpu->arch.prev_cpu)))
> > + return true;
> > +
> > + return false;
> > +}
>
> This seems to be wrong. I'd guess that you need
>
> if (cpumask_test_cpu(vcpu->cpu,
> topology_core_cpumask(vcpu->arch.prev_cpu)))
> --> return false;
> --> return true;

so if the CPU moved to a different socket, it's not a change?
and if nothing happened, it is a change?