Re: [PATCH v11 07/11] KVM: x86: Expose MSR_IA32_PERF_CAPABILITIES for LBR record format

[Xu, Like]

On 2020/5/19 18:53, Peter Zijlstra wrote:
> On Thu, May 14, 2020 at 04:30:50PM +0800, Like Xu wrote:
> > @@ -203,6 +206,12 @@ static int intel_pmu_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> >   	case MSR_CORE_PERF_GLOBAL_OVF_CTRL:
> >   		msr_info->data = pmu->global_ovf_ctrl;
> >   		return 0;
> > +	case MSR_IA32_PERF_CAPABILITIES:
> > +		if (!msr_info->host_initiated &&
> > +			!guest_cpuid_has(vcpu, X86_FEATURE_PDCM))
> > +			return 1;
> I know this is KVM code, so maybe they feel differently, but I find the
> above indentation massively confusing. Consider using: "set cino=:0(0"
> if you're a vim user.
Nice tip and I'll apply it. Thanks.
> > +		msr_info->data = vcpu->arch.perf_capabilities;
> > +		return 0;
> >   	default:
> >   		if ((pmc = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0))) {
> >   			u64 val = pmc_read_counter(pmc);
> > @@ -261,6 +270,16 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> >   			return 0;
> >   		}
> >   		break;
> > +	case MSR_IA32_PERF_CAPABILITIES:
> > +		if (!msr_info->host_initiated ||
> > +			!guest_cpuid_has(vcpu, X86_FEATURE_PDCM))
> > +			return 1;
> Idem.
>
> > +		if (!(data & ~vmx_get_perf_capabilities()))
> > +			return 1;
> > +		if ((data ^ vmx_get_perf_capabilities()) & PERF_CAP_LBR_FMT)
> > +			return 1;
> > +		vcpu->arch.perf_capabilities = data;
> > +		return 0;
> >   	default:
> >   		if ((pmc = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0))) {
> >   			if (!msr_info->host_initiated)