linux-kernel - Re: [PATCH] x86: clean up setup_clear/force_cpu_cap handling

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Date:	Sat, 18 Apr 2009 14:36:05 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: clean up setup_clear/force_cpu_cap handling - resend

ping.

Ingo, can you pick it up?

YH

Yinghai Lu wrote:
> it looks get lost somehow,... resend again.
> 
> Impact: fix and cleanup
> 
> setup_force_cpu_cap() only have one user xen
> but it should not reuse cleared_cpu_cpus. it will have problem
> for smp.
> 
> need to have cpu_cpus_set array too.
> also need to setup handling before all cpus cap AND
> 
> Signed-off-by: Yinghai Lu <yinghai.lu@...nel.org>
> 
> ---
>  arch/x86/include/asm/cpufeature.h |    4 ++--
>  arch/x86/include/asm/processor.h  |    3 ++-
>  arch/x86/kernel/cpu/common.c      |   17 ++++++++++++-----
>  3 files changed, 16 insertions(+), 8 deletions(-)
> 
> Index: linux-2.6/arch/x86/include/asm/cpufeature.h
> ===================================================================
> --- linux-2.6.orig/arch/x86/include/asm/cpufeature.h
> +++ linux-2.6/arch/x86/include/asm/cpufeature.h
> @@ -192,11 +192,11 @@ extern const char * const x86_power_flag
>  #define clear_cpu_cap(c, bit)	clear_bit(bit, (unsigned long *)((c)->x86_capability))
>  #define setup_clear_cpu_cap(bit) do { \
>  	clear_cpu_cap(&boot_cpu_data, bit);	\
> -	set_bit(bit, (unsigned long *)cleared_cpu_caps); \
> +	set_bit(bit, (unsigned long *)cpu_caps_cleared); \
>  } while (0)
>  #define setup_force_cpu_cap(bit) do { \
>  	set_cpu_cap(&boot_cpu_data, bit);	\
> -	clear_bit(bit, (unsigned long *)cleared_cpu_caps);	\
> +	set_bit(bit, (unsigned long *)cpu_caps_set);	\
>  } while (0)
>  
>  #define cpu_has_fpu		boot_cpu_has(X86_FEATURE_FPU)
> Index: linux-2.6/arch/x86/include/asm/processor.h
> ===================================================================
> --- linux-2.6.orig/arch/x86/include/asm/processor.h
> +++ linux-2.6/arch/x86/include/asm/processor.h
> @@ -135,7 +135,8 @@ extern struct cpuinfo_x86	boot_cpu_data;
>  extern struct cpuinfo_x86	new_cpu_data;
>  
>  extern struct tss_struct	doublefault_tss;
> -extern __u32			cleared_cpu_caps[NCAPINTS];
> +extern __u32			cpu_caps_cleared[NCAPINTS];
> +extern __u32			cpu_caps_set[NCAPINTS];
>  
>  #ifdef CONFIG_SMP
>  DECLARE_PER_CPU(struct cpuinfo_x86, cpu_info);
> Index: linux-2.6/arch/x86/kernel/cpu/common.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/cpu/common.c
> +++ linux-2.6/arch/x86/kernel/cpu/common.c
> @@ -293,7 +293,8 @@ static const char *__cpuinit table_looku
>  	return NULL;		/* Not found */
>  }
>  
> -__u32 cleared_cpu_caps[NCAPINTS] __cpuinitdata;
> +__u32 cpu_caps_cleared[NCAPINTS] __cpuinitdata;
> +__u32 cpu_caps_set[NCAPINTS] __cpuinitdata;
>  
>  void load_percpu_segment(int cpu)
>  {
> @@ -807,6 +808,16 @@ static void __cpuinit identify_cpu(struc
>  #endif
>  
>  	init_hypervisor(c);
> +
> +	/*
> +	 * Clear/Set all flags overriden by options, need do it
> +	 * before following smp all cpus cap AND.
> +	 */
> +	for (i = 0; i < NCAPINTS; i++) {
> +		c->x86_capability[i] &= ~cpu_caps_cleared[i];
> +		c->x86_capability[i] |= cpu_caps_set[i];
> +	}
> +
>  	/*
>  	 * On SMP, boot_cpu_data holds the common feature set between
>  	 * all CPUs; so make sure that we indicate which features are
> @@ -819,10 +830,6 @@ static void __cpuinit identify_cpu(struc
>  			boot_cpu_data.x86_capability[i] &= c->x86_capability[i];
>  	}
>  
> -	/* Clear all flags overriden by options */
> -	for (i = 0; i < NCAPINTS; i++)
> -		c->x86_capability[i] &= ~cleared_cpu_caps[i];
> -
>  #ifdef CONFIG_X86_MCE
>  	/* Init Machine Check Exception if available. */
>  	mcheck_init(c);
> 

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