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

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Date:   Wed, 1 Sep 2021 11:46:02 +0200
From:   Pierre Morel <pmorel@...ux.ibm.com>
To:     David Hildenbrand <david@...hat.com>, kvm@...r.kernel.org
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        borntraeger@...ibm.com, frankja@...ux.ibm.com, cohuck@...hat.com,
        thuth@...hat.com, imbrenda@...ux.ibm.com, hca@...ux.ibm.com,
        gor@...ux.ibm.com
Subject: Re: [PATCH v3 2/3] s390x: KVM: Implementation of Multiprocessor
 Topology-Change-Report



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