linux-kernel - Re: [PATCH 2/4] x86, CPU: Extend TLB size detection for AMD

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Date:	Fri, 03 Aug 2012 11:32:51 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Borislav Petkov <bp@...64.org>
CC:	Alex Shi <alex.shi@...el.com>, X86-ML <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Borislav Petkov <borislav.petkov@....com>
Subject: Re: [PATCH 2/4] x86, CPU: Extend TLB size detection for AMD

On 08/03/2012 09:37 AM, Borislav Petkov wrote:
> From: Borislav Petkov <borislav.petkov@....com>
> 
> TLB characteristics on AMD are in the extended CPUID level, leafs
> 0x8000000{5,6} so we need to check those before doing the detection.
> 
> Signed-off-by: Borislav Petkov <borislav.petkov@....com>
> ---
>  arch/x86/kernel/cpu/common.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
> index d239977f361f..ebab0e77e691 100644
> --- a/arch/x86/kernel/cpu/common.c
> +++ b/arch/x86/kernel/cpu/common.c
> @@ -940,7 +940,8 @@ void __init identify_boot_cpu(void)
>  #else
>  	vgetcpu_set_mode();
>  #endif
> -	if (boot_cpu_data.cpuid_level >= 2)
> +	if (boot_cpu_data.cpuid_level >= 2 ||
> +	    boot_cpu_data.extended_cpuid_level >= 0x80000006)
>  		cpu_detect_tlb(&boot_cpu_data);
>  }
>  

This really belongs in cpu_detect_tlb() itself (or rather, in the
subfunctions called by it.)  Can we just lose the general test here, please?

	-hpa

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