linux-kernel - Re: [PATCH 2/3] [x86, next] Add mce_ser interface in /sys/kernel/debug/mce/ for test

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Date:	Mon, 01 Nov 2010 09:04:10 +0900
From:	Jin Dongming <jin.dongming@...css.fujitsu.com>
To:	Andi Kleen <andi@...stfloor.org>
CC:	Huang Ying <ying.huang@...el.com>, Ingo Molnar <mingo@...e.hu>,
	"H.Peter Anvin" <hpa@...or.com>,
	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>,
	LKLM <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/3] [x86, next] Add mce_ser interface in /sys/kernel/debug/mce/
 for test

(2010/10/29 17:06), Andi Kleen wrote:
> On Fri, Oct 29, 2010 at 01:42:09PM +0900, Jin Dongming wrote:
>> If we want to test the part of mce handler for SRAO and SRAR,  we need to
>> have a test machine whose CPU supports MCG_SER_P. If we don't have such
>> machine, we can not test the part of mce handler for SRAO and SRAR.
>>
>> With this interface we can test the part of mce handler for SRAO and SRAR
>> by setting mce_ser 1 on the machine which does not support MCG_SER_P.
>>
>> Usage:
>>         if val == 1 or val == 0
>>            Set val to mce_ser.
>>         else
>>            Ser the original value to mce_ser.
>>
>> Note:
>>     Please don't use mce_ser interface except mce test.
>>     Because when the real mce exception happened, the unsuitable set
>>     with this interface maybe change the real process of mce handler and
>>     lead to a different result.
> 
> Basic idea is good (I have been using a similar patch for quite some time).
> My patch was a little bit simpler though, not bothering with org_ser:
> 
Yes, it is.

But if you set mce_ser with mca_recovery_set(), 
the original value of mce_ser will be changed, is it right?

If a new guy try to test mce with the test machine, he/she may be
confused by the value of mce_ser. So I think how to tell him
the original value is also important.
> ---
> 
> MCE: Add an debugfs interface to force MCA recovery
> 
> This is useful to run the MCA recovery test cases using
> error injection on a non MCA recovery capable system.
> 
> On a system without MCA recovery this should be a nop.
> 
> Signed-off-by: Andi Kleen <ak@...ux.intel.com>
> 
> ---
>  arch/x86/kernel/cpu/mcheck/mce.c |   20 ++++++++++++++++++--
>  1 file changed, 18 insertions(+), 2 deletions(-)
> 
> Index: linux/arch/x86/kernel/cpu/mcheck/mce.c
> ===================================================================
> --- linux.orig/arch/x86/kernel/cpu/mcheck/mce.c
> +++ linux/arch/x86/kernel/cpu/mcheck/mce.c
> @@ -2346,13 +2346,26 @@ static int fake_panic_set(void *data, u6
>  	fake_panic = val;
>  	return 0;
>  }
> +static int mca_recovery_get(void *data, u64 *val)
> +{
> +	*val = mce_ser;
> +	return 0;
> +}
> +
> +static int mca_recovery_set(void *data, u64 val)
> +{
> +	mce_ser = val;
> +	return 0;
> +}
>  
>  DEFINE_SIMPLE_ATTRIBUTE(fake_panic_fops, fake_panic_get,
>  			fake_panic_set, "%llu\n");
> +DEFINE_SIMPLE_ATTRIBUTE(mca_recovery_fops, mca_recovery_get,
> +			mca_recovery_set, "%llu\n");
>  
>  static int __init mcheck_debugfs_init(void)
>  {
> -	struct dentry *dmce, *ffake_panic;
> +	struct dentry *dmce, *ffake_panic, *fmca_recovery;
>  
>  	dmce = mce_get_debugfs_dir();
>  	if (!dmce)
> @@ -2361,7 +2374,10 @@ static int __init mcheck_debugfs_init(vo
>  					  &fake_panic_fops);
>  	if (!ffake_panic)
>  		return -ENOMEM;
> -
> +	fmca_recovery = debugfs_create_file("mca_recovery_force",0644,dmce,NULL,
> +					&mca_recovery_fops);
> +	if (!fmca_recovery)
> +		return -ENOMEM;
>  	return 0;
>  }
>  late_initcall(mcheck_debugfs_init);
> --
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> 


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