linux-kernel - Re: [PATCH v9 07/22] KVM: s390: refactor crypto initialization

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Message-ID: <4b3f91be-48ef-ba68-22ba-50088e5d3509@redhat.com>
Date:   Mon, 20 Aug 2018 22:41:58 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Tony Krowiak <akrowiak@...ux.ibm.com>,
        Tony Krowiak <akrowiak@...ux.vnet.ibm.com>,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     freude@...ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, borntraeger@...ibm.com,
        cohuck@...hat.com, kwankhede@...dia.com,
        bjsdjshi@...ux.vnet.ibm.com, pbonzini@...hat.com,
        alex.williamson@...hat.com, pmorel@...ux.vnet.ibm.com,
        alifm@...ux.vnet.ibm.com, mjrosato@...ux.vnet.ibm.com,
        jjherne@...ux.vnet.ibm.com, thuth@...hat.com,
        pasic@...ux.vnet.ibm.com, berrange@...hat.com,
        fiuczy@...ux.vnet.ibm.com, buendgen@...ibm.com,
        frankja@...ux.ibm.com
Subject: Re: [PATCH v9 07/22] KVM: s390: refactor crypto initialization

>>
>>> +	if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_AP))
>>> +		vcpu->arch.sie_block->eca |= ECA_APIE;
>>>   
>>> -	vcpu->arch.sie_block->crycbd = vcpu->kvm->arch.crypto.crycbd;
>>> +	/* If MSAX3 is installed on the guest, set up protected key support */
>>> +	if (test_kvm_facility(vcpu->kvm, 76)) {
>>> +		if (vcpu->kvm->arch.crypto.aes_kw)
>>> +			vcpu->arch.sie_block->ecb3 |= ECB3_AES;
>>> +		if (vcpu->kvm->arch.crypto.dea_kw)
>>> +			vcpu->arch.sie_block->ecb3 |= ECB3_DEA;
>>> +	}
>> As the feature can never change, and aes_kw/dea_kw are only set to 1 in
>> case we have test_kvm_facility(vcpu->kvm, 76), this change is not needed.
>>
>> I think this function can be pretty much left alone. Just add the
>> KVM_S390_VM_CPU_FEAT_AP handling.
> 
> I disagree, what about the case where the KVM_S390_VM_CPU_FEAT_AP is
> configured for the guest but the MSAX3 facility (76) is not?

Then aes_kw/dea_kw can never be set.

kvm_s390_vm_set_crypto() and kvm_s390_crypto_init() correctly test for
facility 76.

Or am I missing a case?

> 
>>
>>>   }
>>>   
>>>   void kvm_s390_vcpu_unsetup_cmma(struct kvm_vcpu *vcpu)
>>>
>>
> 


-- 

Thanks,

David / dhildenb