linux-kernel - Re: [PATCH 2/4] x86/mce/amd: Introduce deferred error interrupt handler

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Date:	Mon, 4 May 2015 14:06:43 -0500
From:	Aravind Gopalakrishnan <aravind.gopalakrishnan@....com>
To:	Borislav Petkov <bp@...en8.de>
CC:	<tglx@...utronix.de>, <mingo@...hat.com>, <hpa@...or.com>,
	<tony.luck@...el.com>, <jiang.liu@...ux.intel.com>,
	<yinghai@...nel.org>, <x86@...nel.org>, <dvlasenk@...hat.com>,
	<JBeulich@...e.com>, <slaoub@...il.com>, <luto@...capital.net>,
	<dave.hansen@...ux.intel.com>, <oleg@...hat.com>,
	<rostedt@...dmis.org>, <rusty@...tcorp.com.au>,
	<prarit@...hat.com>, <linux@...musvillemoes.dk>, <jroedel@...e.de>,
	<andriy.shevchenko@...ux.intel.com>, <macro@...ux-mips.org>,
	<wangnan0@...wei.com>, <linux-kernel@...r.kernel.org>,
	<linux-edac@...r.kernel.org>, Robert Richter <rric@...nel.org>
Subject: Re: [PATCH 2/4] x86/mce/amd: Introduce deferred error interrupt handler

On 5/4/2015 1:46 PM, Borislav Petkov wrote:
>> For deferred errors, the workaround is a little different as it
>> applies to only the given family/model right now. If the workaround
>> needs to be applied for future processors, we can extend the family
>> check for those right?
> Or, you can do the check for all families as we're behind a CPUID bit
> anyway. This is why CPUID bits are a good thing :-)

Yep. Ok, Will do that.

>> If we setup 'm.addr' in amd_threshold_interrupt() and
>> amd_deferred_error_interrupt() properly, then amd_decode_mce() would
>> actually have some value in m->addr to report.
>>
>> I didn't mean to say HW doesn't provide us the information in the addr
>> and/or the misc registers.
> So you can use mce_read_aux(), yeah, you can move it to mce-internal.h


Ok, will do.
Is it ok to grow another patch in a V2 for this instead of fixing it in 
this patch since it's a real bug?
That should be helpful when someone wants to look up git logs of why 
this was done..

>> The addr, misc registers are still valid for threshold, deferred errors.
>> (Of course, misc is valid only if m->status & MCI_STATUS_MISCV)
>>
>> My point was, in __log_error(), we can read relevant status and addr MSRs to
>> be passed to mce_log() as those are the only pieces of information we use in
>> the decoding chain; and discard the m.misc assignment we do for threshold
>> errors.
> But MCx_MISC is important for thresholding errors, it carries the ErrCnt
> and stuff.
>
> So you can pass a parameter to __log_error(..., threshold=true, misc)
> and do
>
> 	if (threshold)
> 		m.misc = misc;
>
> Right?
>

Yeah, just wanted to keep __log_error() as generic as possible and not 
special case for threshold.
But ok, since MCx_MISC is needed, I'll work it up as you suggested.

Thanks,
-Aravind.
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