linux-kernel - Re: [PATCH v1 2/4] x86, CPU: Push TLB detection CPUID check down

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Date:	Tue, 07 Aug 2012 08:35:20 +0800
From:	Alex Shi <alex.shi@...el.com>
To:	Borislav Petkov <bp@...64.org>
CC:	"H. Peter Anvin" <hpa@...or.com>, X86-ML <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Borislav Petkov <borislav.petkov@....com>
Subject: Re: [PATCH v1 2/4] x86, CPU: Push TLB detection CPUID check down

On 08/07/2012 01:00 AM, Borislav Petkov wrote:

> From: Borislav Petkov <borislav.petkov@....com>
> 
> Push the max CPUID leaf check into the ->detect_tlb function and remove
> general test case from the generic path.
> 
> Signed-off-by: Borislav Petkov <borislav.petkov@....com>


Acked-by: Alex Shi <alex.shi@...el.com>

> ---
>  arch/x86/kernel/cpu/common.c | 3 +--
>  arch/x86/kernel/cpu/intel.c  | 4 ++++
>  2 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
> index d239977f361f..080f4a737e3e 100644
> --- a/arch/x86/kernel/cpu/common.c
> +++ b/arch/x86/kernel/cpu/common.c
> @@ -940,8 +940,7 @@ void __init identify_boot_cpu(void)
>  #else
>  	vgetcpu_set_mode();
>  #endif
> -	if (boot_cpu_data.cpuid_level >= 2)
> -		cpu_detect_tlb(&boot_cpu_data);
> +	cpu_detect_tlb(&boot_cpu_data);
>  }
>  
>  void __cpuinit identify_secondary_cpu(struct cpuinfo_x86 *c)
> diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
> index 0a4ce2980a5a..198e019a531a 100644
> --- a/arch/x86/kernel/cpu/intel.c
> +++ b/arch/x86/kernel/cpu/intel.c
> @@ -648,6 +648,10 @@ static void __cpuinit intel_detect_tlb(struct cpuinfo_x86 *c)
>  	int i, j, n;
>  	unsigned int regs[4];
>  	unsigned char *desc = (unsigned char *)regs;
> +
> +	if (c->cpuid_level < 2)
> +		return;
> +
>  	/* Number of times to iterate */
>  	n = cpuid_eax(2) & 0xFF;
>  


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