Messages in this thread |  | | Subject | Re: [PATCH v3 04/14] KVM: s390: device attribute to set AP interpretive execution | From | Halil Pasic <> | Date | Tue, 20 Mar 2018 23:48:32 +0100 |
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On 03/20/2018 06:58 PM, Tony Krowiak wrote: > I spoke with Christian this morning and he made a suggestion which I think would provide the best solution here. > This is my proposal: > 1. Get rid of the KVM_S390_VM_CRYPTO_INTERPRET_AP device attribute and return to setting ECA.28 from the > mdev device open callback. > 2. Since there may be vcpus online at the time the mdev device open is called, we must first take all running vcpus out of > SIE and block them. Christian suggested the kvm_s390_vcpu_block_all(struct kvm *kvm) function will do the trick. So I > propose introducing a function like the following to be called during mdev open:
There is one thing you missed, otherwise I'm *very* satisfied with this proposal.
What you have missed IMHO is vcpu hottplug. So IMHO you should keep kvm->arch.crypto.apie, and update it accordingly ...
> > int kvm_ap_set_interpretive_exec(struct kvm *kvm, bool enable) > { > int i; > struct kvm_vcpu *vcpu; > > if (!test_kvm_cpu_feat(kvm, KVM_S390_VM_CPU_FEAT_AP)) > return -EOPNOTSUPP; > > mutex_lock(&kvm->lock); > > kvm_s390_vcpu_block_all(kvm);
... let's say here.
> > kvm_for_each_vcpu(i, vcpu, kvm) {
And here you can call kvm_s390_vcpu_crypto_setup(vcpu) (the changes to this function will be required for hotplug) if you like
> if (enable) > vcpu->arch.sie_block->eca |= ECA_APIE; > else > vcpu->arch.sie_block->eca &= ~ECA_APIE;
or keep this stuff, it does not really matter to me.
> } > > kvm_s390_vcpu_unblock_all(kvm); > > mutex_unlock(&kvm->lock); > > return 0; > } > > This interface allows us to set ECA.28 even if vcpus are running
I tend to agree. I will give it a proper review when this gets more formal (e.g. v4 (preferably) or patches to be fixed up to this series).
Please don't forget to revisit the discussion on kvm_s390_vm_set_crypto: if the mechanism there isn't right for ECA.28 I think you should tell us why it's OK for the other attributes if it's OK. If it is not then I guess you will want to do a stand alone patch for that.
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