linux-kernel - Re: [PATCH 1/2] KVM: x86/pmu: Set MSR_IA32_MISC_ENABLE

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Date:   Fri, 30 Oct 2020 13:30:58 +0800
From:   Like Xu <like.xu@...ux.intel.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     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>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] KVM: x86/pmu: Set MSR_IA32_MISC_ENABLE_EMON when vPMU
 is enabled

Hi,

Is the community not interested in these two patches?
The second one also appears in the LBR patch set and
will benefit other PMU features later, such as PEBS.

Thanks,
Like Xu

On 2020/10/20 22:57, Like Xu wrote:
> On Intel platforms, software may uses IA32_MISC_ENABLE[7]
> bit to detect whether the performance monitoring facility
> is supported in the processor.
> 
> A write to this PMU available bit will be ignored.
> 
> Cc: Yao Yuan <yuan.yao@...el.com>
> Signed-off-by: Like Xu <like.xu@...ux.intel.com>
> ---
>   arch/x86/kvm/vmx/pmu_intel.c | 2 ++
>   arch/x86/kvm/x86.c           | 1 +
>   2 files changed, 3 insertions(+)
> 
> diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
> index a886a47daebd..01c7d84ecf3e 100644
> --- a/arch/x86/kvm/vmx/pmu_intel.c
> +++ b/arch/x86/kvm/vmx/pmu_intel.c
> @@ -339,6 +339,8 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
>   	if (!pmu->version)
>   		return;
>   
> +	vcpu->arch.ia32_misc_enable_msr |= MSR_IA32_MISC_ENABLE_EMON;
> +
>   	perf_get_x86_pmu_capability(&x86_pmu);
>   	if (guest_cpuid_has(vcpu, X86_FEATURE_PDCM))
>   		vcpu->arch.perf_capabilities = vmx_get_perf_capabilities();
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index c4015a43cc8a..d7b8f98ada93 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3042,6 +3042,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>   		}
>   		break;
>   	case MSR_IA32_MISC_ENABLE:
> +		data &= ~MSR_IA32_MISC_ENABLE_EMON;
>   		if (!kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT) &&
>   		    ((vcpu->arch.ia32_misc_enable_msr ^ data) & MSR_IA32_MISC_ENABLE_MWAIT)) {
>   			if (!guest_cpuid_has(vcpu, X86_FEATURE_XMM3))
>