linux-kernel - Re: [PATCH] x86, MCE, AMD: save IA32_MCi_STATUS before machine_check

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Date:	Tue, 30 Sep 2014 17:56:31 +0800
From:	Chen Yucong <slaoub@...il.com>
To:	Borislav Petkov <bp@...en8.de>
Cc:	tony.luck@...el.com, linux-edac@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86, MCE, AMD: save IA32_MCi_STATUS before
 machine_check_poll() resets it

On Tue, 2014-09-30 at 09:25 +0200, Borislav Petkov wrote:
> >                       if (high & MASK_OVERFLOW_HI) {
> >                               rdmsrl(address, m.misc);
> >                               rdmsrl(MSR_IA32_MCx_STATUS(bank),
> m.status);
> > +                             if (m.status & MCI_STATUS_ADDRV)
> >
> +                                     rdmsrl(MSR_IA32_MCx_ADDR(bank),
> m.addr);
> >                               m.bank = K8_MCE_THRESHOLD_BASE
> >                                      + bank * NR_BLOCKS
> >                                      + block;
> >                               mce_log(&m);
> > -                             return;
> > +
> > +                             wrmsrl(MSR_IA32_MCx_STATUS(bank), 0);
> 
> No, machine_check_poll will clear it anyway and now you're adding a
> purely useless MSR write here which costs.
I just clear it to avoid that the mce_log() call logs the above
threshold event again in machine_check_poll().
> 
> > +                             goto log_mcheck;
> 
> Why goto? It will hit that machine_check_poll below even without
> it... 
It is just used for scanning other banks for recording other valid 
error information.

thx!
cyc

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