Messages in this thread | | | Subject | Re: [PATCH v3 04/14] KVM: s390: device attribute to set AP interpretive execution | From | Tony Krowiak <> | Date | Thu, 15 Mar 2018 19:37:36 -0400 |
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On 03/15/2018 12:00 PM, Pierre Morel wrote: > On 15/03/2018 16:23, Tony Krowiak wrote: >> On 03/14/2018 05:57 PM, Halil Pasic wrote: >>> >>> On 03/14/2018 07:25 PM, Tony Krowiak wrote: >>>> The VFIO AP device model exploits interpretive execution of AP >>>> instructions (APIE) to provide guests passthrough access to AP >>>> devices. This patch introduces a new device attribute in the >>>> KVM_S390_VM_CRYPTO device attribute group to set APIE from >>>> the VFIO AP device defined on the guest. >>>> >>>> Signed-off-by: Tony Krowiak <akrowiak@linux.vnet.ibm.com> >>>> --- >>> [..] >>> >>>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c >>>> index a60c45b..bc46b67 100644 >>>> --- a/arch/s390/kvm/kvm-s390.c >>>> +++ b/arch/s390/kvm/kvm-s390.c >>>> @@ -815,6 +815,19 @@ static int kvm_s390_vm_set_crypto(struct kvm >>>> *kvm, struct kvm_device_attr *attr) >>>> sizeof(kvm->arch.crypto.crycb->dea_wrapping_key_mask)); >>>> VM_EVENT(kvm, 3, "%s", "DISABLE: DEA keywrapping support"); >>>> break; >>>> + case KVM_S390_VM_CRYPTO_INTERPRET_AP: >>>> + if (attr->addr) { >>>> + if (!test_kvm_cpu_feat(kvm, KVM_S390_VM_CPU_FEAT_AP)) >>> Unlock mutex before returning? >> The mutex is unlocked prior to return at the end of the function. >>> >>> Maybe flip conditions (don't allow manipulating apie if feature not >>> there). >>> Clearing the anyways clear apie if feature not there ain't too bad, but >>> rejecting the operation appears nicer to me. >> I think what you're saying is something like this: >> >> if (!test_kvm_cpu_feat(kvm, KVM_S390_VM_CPU_FEAT_AP)) >> return -EOPNOTSUPP; >> >> kvm->arch.crypto.apie = (attr->addr) ? 1 : 0; >> >> I can make arguments for doing this either way, but since the attribute >> is will most likely only be set by an AP device in userspace, I suppose >> it makes sense to allow setting of the attribute if the AP feature is >> installed. It certainly makes sense for the dedicated implementation. >>> >>>> + return -EOPNOTSUPP; > > Obviously Halil is speaking on this return statement. > Which returns without unlocking the mutex. Got it. > > > >
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