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)