linux-kernel - Re: [PATCH v2 1/2] x86/MCE: Add function to allow filtering of MCA errors

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Date:   Fri, 22 Mar 2019 19:05:27 +0000
From:   "Ghannam, Yazen" <Yazen.Ghannam@....com>
To:     Borislav Petkov <bp@...en8.de>
CC:     "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "tony.luck@...el.com" <tony.luck@...el.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "rafal@...ecki.pl" <rafal@...ecki.pl>,
        "clemej@...il.com" <clemej@...il.com>
Subject: Re: [PATCH v2 1/2] x86/MCE: Add function to allow filtering of MCA
 errors

On 3/22/2019 12:24 PM, Borislav Petkov wrote:
> On Thu, Mar 21, 2019 at 08:25:17PM +0000, Ghannam, Yazen wrote:
>> From: Yazen Ghannam <yazen.ghannam@....com>
>>
>> Some systems may report spurious MCA errors. In general, spurious MCA
>> errors may be disabled by clearing a particular bit in MCA_CTL. However,
>> clearing a bit in MCA_CTL may not be recommended for some errors, so the
>> only option is to ignore them.
>>
>> An MCA error is printed and handled after it has been added to the MCE
>> event pool. So an MCA error can be ignored by not adding it to the pool.
>>
>> Create a function pointer to filter MCA errors and use this when adding
>> an error to the MCE event pool.
>>
>> Install a default function that does not filter any errors.
>>
>> Cc: <stable@...r.kernel.org> # 4.14.x
>> Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>
>> ---
>> Link:
>> https://lkml.kernel.org/r/20190307212552.8865-1-Yazen.Ghannam@amd.com
>>
>> v1->v2:
>> * This is a new patch replacing V1 Patch 1 which is no longer needed.
>>
>>  arch/x86/include/asm/mce.h        | 3 +++
>>  arch/x86/kernel/cpu/mce/core.c    | 6 ++++++
>>  arch/x86/kernel/cpu/mce/genpool.c | 3 +++
>>  3 files changed, 12 insertions(+)
>>
>> diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
>> index 22d05e3835f0..0b0b797a959c 100644
>> --- a/arch/x86/include/asm/mce.h
>> +++ b/arch/x86/include/asm/mce.h
>> @@ -253,6 +253,9 @@ extern void mce_disable_bank(int bank);
>>  extern void (*machine_check_vector)(struct pt_regs *, long error_code);
>>  void do_machine_check(struct pt_regs *, long);
>>  
>> +/* Filter MCEs from the decoder chain. */
> 
> That should be something like:
> 
> /* Decides whether to add MCE records to the decoder chain or filter them out. */
> 

Okay. I'll make a change.

>> +extern bool (*filter_mce)(struct mce *m);
>> +
>>  /*
>>   * Threshold handler
>>   */
>> diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
>> index b7fb541a4873..effb40581f08 100644
>> --- a/arch/x86/kernel/cpu/mce/core.c
>> +++ b/arch/x86/kernel/cpu/mce/core.c
>> @@ -1771,6 +1771,12 @@ static void __mcheck_cpu_init_timer(void)
>>  	mce_start_timer(t);
>>  }
>>  
>> +/*
>> + * Don't filter MCEs by default. Install a system-specific function, if needed.
>> + */
> 
> That comment is kinda obvious.
> 

Okay. I'll drop it.

Thanks,
Yazen