linux-kernel - Re: [PATCH 3/6] x86-mce: Clear CMCI enable on all claimed CMCI banks before reboot.

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Message-ID: <CAFQmdRb-qENEhFrEeNzvBrMuBjusZcxvhanTuzL9VmKncv-1Tg@mail.gmail.com>
Date:	Thu, 10 Jul 2014 10:56:05 -0700
From:	Havard Skinnemoen <hskinnemoen@...gle.com>
To:	Borislav Petkov <bp@...en8.de>
Cc:	"Luck, Tony" <tony.luck@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ewout van Bekkum <ewout@...gle.com>
Subject: Re: [PATCH 3/6] x86-mce: Clear CMCI enable on all claimed CMCI banks
 before reboot.

On Thu, Jul 10, 2014 at 9:24 AM, Borislav Petkov <bp@...en8.de> wrote:
> We don't need all that atomicity special fun if we register the reboot
> notifier on the BSP, say from mcheck_init() which is done even pre-SMP.
>
> If that's too early, we can add an initcall or whatever...

OK, will see if I can find a better place for it.

> Also, since this is kexec-only, this all should be nicely enabled only
> on KEXEC kernels. Please use the ifdeffery sparingly :-)
>
> I'm saying that because I'm assuming BIOS will clear those MSRs upon
> warm reset. If it doesn't, then we have a bigger problem.

Even on kexec-enabled kernels, we might be doing a regular BIOS boot.
Is there any way to detect that we're doing a kexec boot and only
clearing the MSRs in that case?

Havard
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