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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