linux-kernel - Re: [PATCH 32/61] KVM: x86: Handle UMIP emulation CPUID adjustment in VMX code

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Message-ID: <87y2ssnh8a.fsf@vitty.brq.redhat.com>
Date:   Mon, 24 Feb 2020 16:21:41 +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 32/61] KVM: x86: Handle UMIP emulation CPUID adjustment in VMX code

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

> Move the CPUID adjustment for UMIP emulation into VMX code to eliminate
> an instance of the undesirable "unsigned f_* = *_supported ? F(*) : 0"
> pattern in the common CPUID handling code.
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> ---
>  arch/x86/kvm/cpuid.c   | 2 --
>  arch/x86/kvm/vmx/vmx.c | 2 ++
>  2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index a5f150204d73..202a6c0f1db8 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_umip = kvm_x86_ops->umip_emulated() ? F(UMIP) : 0;
>  	unsigned f_intel_pt = kvm_x86_ops->pt_supported() ? F(INTEL_PT) : 0;
>  	unsigned f_la57;
>  	unsigned f_pku = kvm_x86_ops->pku_supported() ? F(PKU) : 0;
> @@ -382,7 +381,6 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry)
>  		cpuid_entry_mask(entry, CPUID_7_ECX);
>  		/* Set LA57 based on hardware capability. */
>  		entry->ecx |= f_la57;
> -		entry->ecx |= f_umip;
>  		entry->ecx |= f_pku;
>  		/* PKU is not yet implemented for shadow paging. */
>  		if (!tdp_enabled || !boot_cpu_has(X86_FEATURE_OSPKE))
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 49ee4c600934..9d2e36a5ecb9 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -7111,6 +7111,8 @@ 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 (vmx_umip_emulated())
> +			cpuid_entry_set(entry, X86_FEATURE_UMIP);
>  		break;
>  	default:
>  		break;

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

-- 
Vitaly