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

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Message-ID: <20150306092738.GE3514@pd.tnic>
Date:	Fri, 6 Mar 2015 10:27:38 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
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 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.

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

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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