linux-kernel - Re: [PATCH v6] x86: mce: kexec: switch MCE handler for kexec/kdump

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Message-ID: <20150306093212.GB14982@hori1.linux.bs1.fc.nec.co.jp>
Date:	Fri, 6 Mar 2015 09:32:12 +0000
From:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
To:	Borislav Petkov <bp@...en8.de>
CC:	"Luck, Tony" <tony.luck@...el.com>,
	Prarit Bhargava <prarit@...hat.com>,
	Vivek Goyal <vgoyal@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Junichi Nomura <j-nomura@...jp.nec.com>,
	Kiyoshi Ueda <k-ueda@...jp.nec.com>
Subject: Re: [PATCH v6] x86: mce: kexec: switch MCE handler for kexec/kdump

On Fri, Mar 06, 2015 at 10:27:38AM +0100, Borislav Petkov wrote:
> On Fri, Mar 06, 2015 at 09:09:30AM +0000, Naoya Horiguchi wrote:
> > I'm not sure why that works, could you elabroate it?
> 
> Because the _safe() variants are only for handling reads to possibly
> non-existent MSRs. The _STATUS MSRs which you're accessing are
> guaranteed to be present, otherwise __mcheck_cpu_cap_init() would've
> disabled MCA on the first kernel, thus the mca_cfg.disabled check.

Great, thanks.

> We can always switch to the _safe() variants later if really needed - I
> just don't see the need for them right now.

OK, I'll do with rdmsrl().

Thanks,
Naoya Horiguchi--
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