linux-kernel - Re: [PATCH 35/61] KVM: x86: Handle Intel PT CPUID adjustment in VMX code

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Message-ID: <87pne4ngty.fsf@vitty.brq.redhat.com>
Date:   Mon, 24 Feb 2020 16:30:17 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Paolo Bonzini <pbonzini@...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 35/61] KVM: x86: Handle Intel PT CPUID adjustment in VMX code

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

> Move the Processor Trace CPUID adjustment into VMX code to eliminate
> an instance of the undesirable "unsigned f_* = *_supported ? F(*) : 0"
> pattern in the common CPUID handling code, and to pave the way toward
> eventually removing ->pt_supported().
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> ---
>  arch/x86/kvm/cpuid.c   | 3 +--
>  arch/x86/kvm/vmx/vmx.c | 3 +++
>  2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index fc507270f3f3..f4a3655451dd 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -339,7 +339,6 @@ static int __do_cpuid_func_emulated(struct kvm_cpuid_array *array, u32 func)
>  
>  static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry)
>  {
> -	unsigned f_intel_pt = kvm_x86_ops->pt_supported() ? F(INTEL_PT) : 0;
>  	unsigned f_la57;
>  
>  	/* cpuid 7.0.ebx */
> @@ -348,7 +347,7 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry)
>  		F(BMI2) | F(ERMS) | 0 /*INVPCID*/ | F(RTM) | 0 /*MPX*/ | F(RDSEED) |
>  		F(ADX) | F(SMAP) | F(AVX512IFMA) | F(AVX512F) | F(AVX512PF) |
>  		F(AVX512ER) | F(AVX512CD) | F(CLFLUSHOPT) | F(CLWB) | F(AVX512DQ) |
> -		F(SHA_NI) | F(AVX512BW) | F(AVX512VL) | f_intel_pt;
> +		F(SHA_NI) | F(AVX512BW) | F(AVX512VL) | 0 /*INTEL_PT*/;
>  
>  	/* cpuid 7.0.ecx*/
>  	const u32 kvm_cpuid_7_0_ecx_x86_features =
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 3990ba691d07..fcec3d8a0176 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -7111,6 +7111,9 @@ static void vmx_set_supported_cpuid(struct kvm_cpuid_entry2 *entry)
>  			cpuid_entry_set(entry, X86_FEATURE_MPX);
>  		if (boot_cpu_has(X86_FEATURE_INVPCID) && cpu_has_vmx_invpcid())
>  			cpuid_entry_set(entry, X86_FEATURE_INVPCID);
> +		if (boot_cpu_has(X86_FEATURE_INTEL_PT) &&
> +		    vmx_pt_mode_is_host_guest())
> +			cpuid_entry_set(entry, X86_FEATURE_INTEL_PT);
>  		if (vmx_umip_emulated())
>  			cpuid_entry_set(entry, X86_FEATURE_UMIP);

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

-- 
Vitaly