linux-kernel - Re: [PATCH 1/2 v2] x86, mce, severity: extend the the mce

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Date:	Thu, 6 Nov 2014 19:56:38 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	"Luck, Tony" <tony.luck@...el.com>
Cc:	Chen Yucong <slaoub@...il.com>,
	"ak@...ux.intel.com" <ak@...ux.intel.com>,
	"aravind.gopalakrishnan@....com" <aravind.gopalakrishnan@....com>,
	"linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2 v2] x86, mce, severity: extend the the mce_severity

On Thu, Nov 06, 2014 at 06:32:37PM +0000, Luck, Tony wrote:
> > Basically, this check is being done only for machine check exceptions
> > only.
> 
> But you proposed setting excp by looking at mcg_status:
> > excp = ((m->mcg_status & MCG_STATUS_MCIP) ? EXCP_CONTEXT : NO_EXCP);
> 
> Which makes the code rather self referential.  If we actually did arrive in MCE handler
> with MCIP == 0 ... then your code would pretend that we'd arrived here from the
> poll code, and skip over the test for MCIP - so fail to report that MCIP wasn't set.

Is that ever possible - to have a discrepancy between the setting of
MCIP and where we call mce_severity()?

I'm under the assumption that at all times, when we get a MCE, MCIP will
be set. For example, mce_gather_info() reads MCG_STATUS before we call
mce_severity() in do_machine_check().

Or am I missing something?

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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