linux-kernel - Re: [PATCH 28/61] KVM: x86: Refactor cpuid

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Date:   Mon, 24 Feb 2020 14:49:33 +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 28/61] KVM: x86: Refactor cpuid_mask() to auto-retrieve the register

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

> Use the recently introduced cpuid_entry_get_reg() to automatically get
> the appropriate register when masking a CPUID entry.
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> ---
>  arch/x86/kvm/cpuid.c | 28 +++++++++++++++-------------
>  1 file changed, 15 insertions(+), 13 deletions(-)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 195f4dcc8c6a..cb5870a323cc 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -254,10 +254,12 @@ int kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu *vcpu,
>  	return r;
>  }
>  
> -static __always_inline void cpuid_mask(u32 *word, int wordnum)
> +static __always_inline void cpuid_entry_mask(struct kvm_cpuid_entry2 *entry,
> +					     enum cpuid_leafs leaf)
>  {
> -	reverse_cpuid_check(wordnum);
> -	*word &= boot_cpu_data.x86_capability[wordnum];
> +	u32 *reg = cpuid_entry_get_reg(entry, leaf * 32);
> +
> +	*reg &= boot_cpu_data.x86_capability[leaf];
>  }
>  
>  struct kvm_cpuid_array {
> @@ -373,13 +375,13 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry)
>  	case 0:
>  		entry->eax = min(entry->eax, 1u);
>  		entry->ebx &= kvm_cpuid_7_0_ebx_x86_features;
> -		cpuid_mask(&entry->ebx, CPUID_7_0_EBX);
> +		cpuid_entry_mask(entry, CPUID_7_0_EBX);
>  		/* TSC_ADJUST is emulated */
>  		cpuid_entry_set(entry, X86_FEATURE_TSC_ADJUST);
>  
>  		entry->ecx &= kvm_cpuid_7_0_ecx_x86_features;
>  		f_la57 = cpuid_entry_get(entry, X86_FEATURE_LA57);
> -		cpuid_mask(&entry->ecx, CPUID_7_ECX);
> +		cpuid_entry_mask(entry, CPUID_7_ECX);
>  		/* Set LA57 based on hardware capability. */
>  		entry->ecx |= f_la57;
>  		entry->ecx |= f_umip;
> @@ -389,7 +391,7 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry)
>  			cpuid_entry_clear(entry, X86_FEATURE_PKU);
>  
>  		entry->edx &= kvm_cpuid_7_0_edx_x86_features;
> -		cpuid_mask(&entry->edx, CPUID_7_EDX);
> +		cpuid_entry_mask(entry, CPUID_7_EDX);
>  		if (boot_cpu_has(X86_FEATURE_IBPB) && boot_cpu_has(X86_FEATURE_IBRS))
>  			cpuid_entry_set(entry, X86_FEATURE_SPEC_CTRL);
>  		if (boot_cpu_has(X86_FEATURE_STIBP))
> @@ -507,9 +509,9 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
>  		break;
>  	case 1:
>  		entry->edx &= kvm_cpuid_1_edx_x86_features;
> -		cpuid_mask(&entry->edx, CPUID_1_EDX);
> +		cpuid_entry_mask(entry, CPUID_1_EDX);
>  		entry->ecx &= kvm_cpuid_1_ecx_x86_features;
> -		cpuid_mask(&entry->ecx, CPUID_1_ECX);
> +		cpuid_entry_mask(entry, CPUID_1_ECX);
>  		/* we support x2apic emulation even if host does not support
>  		 * it since we emulate x2apic in software */
>  		cpuid_entry_set(entry, X86_FEATURE_X2APIC);
> @@ -619,7 +621,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
>  			goto out;
>  
>  		entry->eax &= kvm_cpuid_D_1_eax_x86_features;
> -		cpuid_mask(&entry->eax, CPUID_D_1_EAX);
> +		cpuid_entry_mask(entry, CPUID_D_1_EAX);
>  		if (entry->eax & (F(XSAVES)|F(XSAVEC)))
>  			entry->ebx = xstate_required_size(supported_xcr0, true);
>  		else
> @@ -699,9 +701,9 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
>  		break;
>  	case 0x80000001:
>  		entry->edx &= kvm_cpuid_8000_0001_edx_x86_features;
> -		cpuid_mask(&entry->edx, CPUID_8000_0001_EDX);
> +		cpuid_entry_mask(entry, CPUID_8000_0001_EDX);
>  		entry->ecx &= kvm_cpuid_8000_0001_ecx_x86_features;
> -		cpuid_mask(&entry->ecx, CPUID_8000_0001_ECX);
> +		cpuid_entry_mask(entry, CPUID_8000_0001_ECX);
>  		break;
>  	case 0x80000007: /* Advanced power management */
>  		/* invariant TSC is CPUID.80000007H:EDX[8] */
> @@ -720,7 +722,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
>  		entry->eax = g_phys_as | (virt_as << 8);
>  		entry->edx = 0;
>  		entry->ebx &= kvm_cpuid_8000_0008_ebx_x86_features;
> -		cpuid_mask(&entry->ebx, CPUID_8000_0008_EBX);
> +		cpuid_entry_mask(entry, CPUID_8000_0008_EBX);
>  		/*
>  		 * AMD has separate bits for each SPEC_CTRL bit.
>  		 * arch/x86/kernel/cpu/bugs.c is kind enough to
> @@ -763,7 +765,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
>  		break;
>  	case 0xC0000001:
>  		entry->edx &= kvm_cpuid_C000_0001_edx_x86_features;
> -		cpuid_mask(&entry->edx, CPUID_C000_0001_EDX);
> +		cpuid_entry_mask(entry, CPUID_C000_0001_EDX);
>  		break;
>  	case 3: /* Processor serial number */
>  	case 5: /* MONITOR/MWAIT */


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

-- 
Vitaly