linux-kernel - Re: [PATCH] mm/x86: Patch out arch_flush_lazy_mmu

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Date:	Thu, 28 Feb 2013 19:05:40 -0500
From:	Josh Boyer <jwboyer@...hat.com>
To:	Borislav Petkov <bp@...en8.de>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>, hpa@...or.com,
	mingo@...hat.com, tglx@...utronix.de, konrad.wilk@...cle.com,
	rostedt@...dmis.org, gregkh@...uxfoundation.org,
	samu.kallio@...rdeencloud.com, kraman@...hat.com,
	xen-devel@...ts.xen.org, linux-kernel@...r.kernel.org,
	stable@...nel.org
Subject: Re: [PATCH] mm/x86: Patch out arch_flush_lazy_mmu_mode() when
 running on bare metal

On Fri, Mar 01, 2013 at 12:37:20AM +0100, Borislav Petkov wrote:
> On Thu, Feb 28, 2013 at 05:55:49PM -0500, Boris Ostrovsky wrote:
> > Invoking arch_flush_lazy_mmu_mode() results in calls to
> > preempt_enable()/disable() which may have performance impact.
> > 
> > Since lazy MMU is not used on bare metal we can patch away
> > arch_flush_lazy_mmu_mode() so that it is never called in such
> > environment.
> > 
> > Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
> 
> Looks straight-forward enough to me.
> 
> Acked-by: Borislav Petkov <bp@...e.de>

I'll try to get someone to test this tomorrow.

josh
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