Messages in this thread | | | Subject | Re: [PATCH v10 24/26] KVM: s390: device attrs to enable/disable AP interpretation | From | Tony Krowiak <> | Date | Tue, 25 Sep 2018 09:26:12 -0400 |
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On 09/25/2018 03:32 AM, David Hildenbrand wrote: > On 24/09/2018 20:42, Tony Krowiak wrote: >> On 09/24/2018 12:25 PM, Tony Krowiak wrote: >>> On 09/24/2018 07:23 AM, David Hildenbrand wrote: >> >> (...) >> >>>> Will you also fixup this patch to expose KVM_S390_VM_CRYPTO_ENABLE_APIE >>>> only if supported by HW? (ap_instructions_available) >>> >>> Given that this patch DOES expose KVM_S390_VM_CRYPTO_ENABLE_APIE only if >>> supported by HW, I assume you are talking about >>> KVM_S390_VM_CRYPTO_DISABLE_APIE. I didn't check >>> ap_instructions_available() for disabling APIE because I didn't >>> think it necessary given that ECA.28 will be set to 0 (intercept) by >>> default, whether AP instructions are installed or not; so why not allow >>> disabling apie. I suppose from the perspective of consistency, since the >>> kvm_s390_vm_has_attr() function checks ap_instructions_available() for >>> both attributes, then it probably makes sense to add that check to >>> KVM_S390_VM_CRYPTO_DISABLE_APIE here. Then again, we could make a change >>> in ap_instructions_available() to allow KVM_S390_VM_CRYPTO_DISABLE_APIE >>> regardless of whether AP instructions are available. It boils down to >>> whether APIE needs to be dynamically disabled at some point when it has >>> been enabled. The only case I can think of where that may be necessary >>> is if a guest is migrated to a system without AP instructions. I don't >>> think that can happen and may even be protected against precisely >>> because the VM attributes won't be available on the target system due to >>> no AP instructions. What say you? >>> >> David, >> >> I'm sorry, I misinterpreted what you were asking for. Check out the >> fixup! patch below and let me know if that is what you are looking for. >> If so, I will integrate that change and post v11 tomorrow (Tuesday 9/24). >> >> -----------------------------------8<----------------------------------- >> >> From: Tony Krowiak <akrowiak@linux.ibm.com> >> Date: Mon, 24 Sep 2018 14:18:37 -0400 >> Subject: [FIXUP v10] fixup! KVM: s390: device attrs to enable/disable AP >> interpretation >> >> --- >> arch/s390/kvm/kvm-s390.c | 9 ++++++++- >> 1 file changed, 8 insertions(+), 1 deletion(-) >> >> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c >> index 6654bb1fc26a..a528558baa78 100644 >> --- a/arch/s390/kvm/kvm-s390.c >> +++ b/arch/s390/kvm/kvm-s390.c >> @@ -901,6 +901,10 @@ static int kvm_s390_vm_set_crypto(struct kvm *kvm, >> struct kvm_device_attr *attr) >> kvm->arch.crypto.apie = 1; >> break; >> case KVM_S390_VM_CRYPTO_DISABLE_APIE: >> + if (!ap_instructions_available()) { >> + mutex_unlock(&kvm->lock); >> + return -EOPNOTSUPP; >> + } >> kvm->arch.crypto.apie = 0; >> break; >> default: >> @@ -1509,9 +1513,11 @@ static int kvm_s390_vm_has_attr(struct kvm *kvm, >> struct kvm_device_attr *attr) >> case KVM_S390_VM_CRYPTO_ENABLE_DEA_KW: >> case KVM_S390_VM_CRYPTO_DISABLE_AES_KW: >> case KVM_S390_VM_CRYPTO_DISABLE_DEA_KW: >> + ret = 0; >> + break; >> case KVM_S390_VM_CRYPTO_ENABLE_APIE: >> case KVM_S390_VM_CRYPTO_DISABLE_APIE: >> - ret = 0; >> + ret = ap_instructions_available(); > > Just a little remark, I guess we want to report 0 if available and > -ENXIO if not.
That makes sense ... I'll fix it.
>
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