Re: [PATCH v5 11/19] KVM:VMX: Emulate read and write to CET MSRs

[Paolo Bonzini]

On 8/4/23 23:27, Sean Christopherson wrote:
> > > +
> > > +	if (!kvm_cpu_cap_has(X86_FEATURE_SHSTK) &&
> > > +	    !kvm_cpu_cap_has(X86_FEATURE_IBT))
> > > +		return false;
> > > +
> > > +	return msr->host_initiated ||
> > > +		guest_cpuid_has(vcpu, X86_FEATURE_IBT) ||
> > > +		guest_cpuid_has(vcpu, X86_FEATURE_SHSTK);
>
> Similar to my suggestsion for XSS, I think we drop the waiver for host_initiated
> accesses, i.e. require the feature to be enabled and exposed to the guest, even
> for the host.

No, please don't.  Allowing host-initiated accesses is what makes it 
possible to take the list of MSR indices and pass it blindly to 
KVM_GET_MSR and KVM_SET_MSR.  This should be documented, will send a patch.

Paolo