On Wed, Feb 28, 2024, Paolo Bonzini wrote: > On Wed, Feb 28, 2024 at 5:39 PM Sean Christopherson <seanjc@xxxxxxxxxx> wrote: > > > > This doesn't work. The ENC flag gets set on any SNP *capable* CPU, which results > > > > in false positives for SEV and SEV-ES guests[*]. > > > > > > You didn't look at the patch did you? :) > > > > Guilty, sort of. I looked (and tested) the patch from the TDX series, but I didn't > > look at what you postd. But it's a moot point, because now I did look at what you > > posted, and it's still broken :-) > > > > > It does check for has_private_mem (alternatively I could have dropped the bit > > > in SVM code for SEV and SEV-ES guests). > > > > The problem isn't with *KVM* setting the bit, it's with *hardware* setting the > > bit for SEV and SEV-ES guests. That results in this: > > > > .is_private = vcpu->kvm->arch.has_private_mem && (err & PFERR_GUEST_ENC_MASK), > > > > marking the fault as private. Which, in a vacuum, isn't technically wrong, since > > from hardware's perspective the vCPU access was "private". But from KVM's > > perspective, SEV and SEV-ES guests don't have private memory > > vcpu->kvm->arch.has_private_mem is the flag from the SEV VM types > series. It's false on SEV and SEV-ES VMs, therefore fault->is_private > is going to be false as well. Is it ENOCOFFEE for you or ENODINNER for > me? :) *sigh*, ENOCOFFEE.
