linux-kernel - Re: [RFC PATCH 1/6] x86/CPU: Add X86_FEATURE

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Message-ID: <20161206080806.mh6wnm3gqe7czvs4@pd.tnic>
Date:   Tue, 6 Dec 2016 09:08:06 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     x86@...nel.org, One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Brian Gerst <brgerst@...il.com>,
        Matthew Whitehead <tedheadster@...il.com>,
        Borislav Petkov <bp@...e.de>
Subject: Re: [RFC PATCH 1/6] x86/CPU: Add X86_FEATURE_CPUID

On Mon, Dec 05, 2016 at 05:01:10PM -0800, Andy Lutomirski wrote:
> From: Borislav Petkov <bp@...e.de>
> 
> Add a synthetic CPUID flag denoting whether the CPU sports the CPUID
> instruction or not. This will come useful later when accomodating
> CPUID-less CPUs.
> 
> Signed-off-by: Borislav Petkov <bp@...e.de>
> Signed-off-by: Andy Lutomirski <luto@...nel.org>
> ---
>  arch/x86/include/asm/cpufeatures.h | 2 +-
>  arch/x86/kernel/cpu/common.c       | 7 ++++---
>  2 files changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
> index a4f9aee62217..e6be43b2679a 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -100,7 +100,7 @@
>  #define X86_FEATURE_XTOPOLOGY	( 3*32+22) /* cpu topology enum extensions */
>  #define X86_FEATURE_TSC_RELIABLE ( 3*32+23) /* TSC is known to be reliable */
>  #define X86_FEATURE_NONSTOP_TSC	( 3*32+24) /* TSC does not stop in C states */
> -/* free, was #define X86_FEATURE_CLFLUSH_MONITOR ( 3*32+25) * "" clflush reqd with monitor */
> +#define X86_FEATURE_CPUID	( 3*32+25) /* CPU has CPUID instruction itself */
>  #define X86_FEATURE_EXTD_APICID	( 3*32+26) /* has extended APICID (8 bits) */
>  #define X86_FEATURE_AMD_DCM     ( 3*32+27) /* multi-node processor */
>  #define X86_FEATURE_APERFMPERF	( 3*32+28) /* APERFMPERF */
> diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
> index cc9e980c68ec..37f031f39e27 100644
> --- a/arch/x86/kernel/cpu/common.c
> +++ b/arch/x86/kernel/cpu/common.c
> @@ -800,14 +800,12 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
>  	memset(&c->x86_capability, 0, sizeof c->x86_capability);
>  	c->extended_cpuid_level = 0;
>  
> -	if (!have_cpuid_p())
> -		identify_cpu_without_cpuid(c);
> -
>  	/* cyrix could have cpuid enabled via c_identify()*/
>  	if (have_cpuid_p()) {
>  		cpu_detect(c);
>  		get_cpu_vendor(c);
>  		get_cpu_cap(c);
> +		setup_force_cpu_cap(X86_FEATURE_CPUID);
>  
>  		if (this_cpu->c_early_init)
>  			this_cpu->c_early_init(c);
> @@ -817,6 +815,9 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
>  
>  		if (this_cpu->c_bsp_init)
>  			this_cpu->c_bsp_init(c);
> +	 } else {
> +		identify_cpu_without_cpuid(c);
> +		setup_clear_cpu_cap(X86_FEATURE_CPUID);

checkpatch complains here:

WARNING: Statements should start on a tabstop
#68: FILE: arch/x86/kernel/cpu/common.c:818:
+        } else {


Please reflow tabs.

-- 
Regards/Gruss,
    Boris.

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