Re: [PATCH 1/2] KVM: vmx, pmu: accept 0 for absent MSRs when host-initiated

[Paolo Bonzini]

On 5/31/22 20:37, Sean Christopherson wrote:
> > +
> >   		/*
> >   		 * Writing depth MSR from guest could either setting the
> >   		 * MSR or resetting the LBR records with the side-effect.
> > @@ -535,6 +542,8 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> >   	case MSR_ARCH_LBR_CTL:
> >   		if (!arch_lbr_ctl_is_valid(vcpu, data))
> >   			break;
> > +		if (!guest_cpuid_has(vcpu, X86_FEATURE_ARCH_LBR))
> > +			return 0;
>
> Similar bug here.
>
> Can we just punt this out of kvm/queue until its been properly reviewed?

Yes, I agree.  I have started making some changes and pushed the result 
to kvm/arch-lbr-for-weijiang.

Most of the MSR handling is rewritten (and untested).

The nested VMX handling was also completely broken so I just removed it. 
 Instead, KVM should be adjusted so that it does not whine.

Paolo