linux-kernel - Re: [PATCH v11 07/11] KVM: x86: Expose MSR_IA32_PERF

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Message-ID: <07806259-d9dd-53ec-1b63-84d8e081a296@intel.com>
Date:   Tue, 19 May 2020 20:19:21 +0800
From:   "Xu, Like" <like.xu@...el.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Like Xu <like.xu@...ux.intel.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>, ak@...ux.intel.com,
        wei.w.wang@...el.com
Subject: Re: [PATCH v11 07/11] KVM: x86: Expose MSR_IA32_PERF_CAPABILITIES for
 LBR record format

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)