Messages in this thread | | | Subject | Re: [PATCH v10 11/26] s390: vfio-ap: implement mediated device open callback | From | Tony Krowiak <> | Date | Mon, 24 Sep 2018 14:43:43 -0400 |
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On 09/24/2018 02:40 PM, David Hildenbrand wrote: > On 24/09/2018 18:07, Tony Krowiak wrote: >> On 09/24/2018 04:40 AM, David Hildenbrand wrote: >>> >>>> /** >>>> - * Verify that the AP instructions are available on the guest. This is >>>> indicated >>>> - * via the KVM_S390_VM_CPU_FEAT_AP CPU model feature. >>>> + * Verify that the AP instructions are being interpreted by firmware >>>> for the >>>> + * guest. This is indicated by the kvm->arch.crypto.apie flag. >>>> */ >>>> static int kvm_ap_validate_crypto_setup(struct kvm *kvm) >>>> { >>>> - if (test_bit_inv(KVM_S390_VM_CPU_FEAT_AP, kvm->arch.cpu_feat)) >>>> + if (kvm->arch.crypto.apie) >>>> return 0; >>> >>> I wonder if this check makes sense, because apie can be toggled during >>> runtime. I guess it would be sufficient to check if the ap control block >>> is available and apie is supported by the HW. >> >> I am not clear about what you are getting at here, but I'll attempt >> to respond. There is no need to check if the AP control block (CRYCB) >> is available as the address is set in the CRYCBD three instructions >> above, even if AP instructions are not available. Regarding whether apie >> is supported by the hardware, the value of vcpu->kvm->arch.crypto.apie >> can not be set unless it is supported by the HW. In the patch (24/26) >> that provides the VM attributes to toggle this value, it can only be >> turned on if the AP instructions are available. I might also note that >> the kvm_ap_validate_crypto_setup() function is called whenever one of >> the VM crypto attributes is changed, so it makes sense that decisions >> made in this function are based on a change to a VM crypto attribute. In >> my first pass at changing this function, I checked >> ap_instructions_available() here, but after considering all of the >> above, it made sense to me to check the apie flag. >> > > I prefer ap_instructions_available(). As I said, kvm->arch.crypto.apie > is a moving target.
Okay then.
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