Re: [PATCH v3 2/3] s390x: KVM: Implementation of Multiprocessor Topology-Change-Report

Pierre Morel
2021-09-01T09:46:13Z

On 8/31/21 4:03 PM, David Hildenbrand wrote:
> On 03.08.21 10:26, Pierre Morel wrote:

...snip...

>> @@ -819,6 +820,23 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
>> struct kvm_enable_cap *cap)
>>           icpt_operexc_on_all_vcpus(kvm);
>>           r = 0;
>>           break;
>> +    case KVM_CAP_S390_CPU_TOPOLOGY:
>> +        mutex_lock(&kvm->lock);
>> +        if (kvm->created_vcpus) {
>> +            r = -EBUSY;
>> +        } else {
>> +            set_kvm_facility(kvm->arch.model.fac_mask, 11);
>> +            set_kvm_facility(kvm->arch.model.fac_list, 11);
>> +            r = 0;
>> +        }
>> +        mutex_unlock(&kvm->lock);
>> +        VM_EVENT(kvm, 3, "ENABLE: CPU TOPOLOGY %s",
>> +             r ? "(not available)" : "(success)");
>> +        break;
>> +
>> +        r = -EINVAL;
>> +        break;
>> +
>>       default:
>>           r = -EINVAL;
>>           break;

This above enables the facility 11.

...snip...

>> @@ -3198,6 +3239,11 @@ static int kvm_s390_vcpu_setup(struct kvm_vcpu
>> *vcpu)
>>           vcpu->arch.sie_block->ecb |= ECB_HOSTPROTINT;
>>       if (test_kvm_facility(vcpu->kvm, 9))
>>           vcpu->arch.sie_block->ecb |= ECB_SRSI;
>> +
>> +    /* PTF needs both host and guest facilities to enable
>> interpretation */
>> +    if (test_kvm_facility(vcpu->kvm, 11) && test_facility(11))
>> +        vcpu->arch.sie_block->ecb |= ECB_PTF;
>
>
> Again, doesn't test_kvm_facility(vcpu->kvm, 11) imply that we have host
> support by checking fac_mask?
>

--
Pierre Morel
IBM Lab Boeblingen