linux-kernel - Re: [PATCH 05/26] KVM: x86: Move MSR_TSC_AUX existence checks into vendor code

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Message-ID: <87blqdksj7.fsf@vitty.brq.redhat.com>
Date:   Wed, 05 Feb 2020 15:39:08 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [PATCH 05/26] KVM: x86: Move MSR_TSC_AUX existence checks into vendor code

Sean Christopherson <sean.j.christopherson@...el.com> writes:

> Move the MSR_TSC_AUX existence check into vendor code using the newly
> introduced ->has_virtualized_msr() hook to help pave the way toward the
> removal of ->rdtscp_supported().
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> ---
>  arch/x86/kvm/svm.c     | 7 +++++++
>  arch/x86/kvm/vmx/vmx.c | 7 +++++++
>  arch/x86/kvm/x86.c     | 4 ----
>  3 files changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 1f9323fbad81..4c8427f57b71 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -5987,6 +5987,13 @@ static bool svm_cpu_has_accelerated_tpr(void)
>  
>  static bool svm_has_virtualized_msr(u32 index)
>  {
> +	switch (index) {
> +	case MSR_TSC_AUX:
> +		return boot_cpu_has(X86_FEATURE_RDTSCP);
> +	default:
> +		break;
> +	}
> +
>  	return true;
>  }
>  
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 3f2c094434e8..9588914e941e 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6276,6 +6276,13 @@ static void vmx_handle_exit_irqoff(struct kvm_vcpu *vcpu,
>  
>  static bool vmx_has_virtualized_msr(u32 index)
>  {
> +	switch (index) {
> +	case MSR_TSC_AUX:
> +		return cpu_has_vmx_rdtscp();
> +	default:
> +		break;
> +	}
> +
>  	return true;
>  }
>  
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 94f90fe1c0de..a8619c52ea86 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -5241,10 +5241,6 @@ static void kvm_init_msr_list(void)
>  			if (!kvm_mpx_supported())
>  				continue;
>  			break;
> -		case MSR_TSC_AUX:
> -			if (!kvm_x86_ops->rdtscp_supported())
> -				continue;
> -			break;
>  		case MSR_IA32_RTIT_CTL:
>  		case MSR_IA32_RTIT_STATUS:
>  			if (!kvm_x86_ops->pt_supported())

Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>

-- 
Vitaly