linux-kernel - Re: [PATCH 2/4] x86/pat: Merge pat_init_cache

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Date:	Mon, 01 Jun 2015 12:15:54 -0600
From:	Toshi Kani <toshi.kani@...com>
To:	Borislav Petkov <bp@...en8.de>
Cc:	jgross@...e.com, Andrew Morton <akpm@...ux-foundation.org>,
	Andy Lutomirski <luto@...capital.net>, arnd@...db.de,
	Elliott@...com, hch@....de, hmh@....eng.br,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
	konrad.wilk@...cle.com, linux-mm <linux-mm@...ck.org>,
	linux-nvdimm@...ts.01.org, "Luis R. Rodriguez" <mcgrof@...e.com>,
	stefan.bader@...onical.com, Thomas Gleixner <tglx@...utronix.de>,
	x86-ml <x86@...nel.org>, yigal@...xistor.com,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/4] x86/pat: Merge pat_init_cache_modes() into its
 caller

On Sun, 2015-05-31 at 12:23 +0200, Borislav Petkov wrote:
> On Sun, May 31, 2015 at 11:48:04AM +0200, Borislav Petkov wrote:
> > From: Borislav Petkov <bp@...e.de>
> > 
> > This way we can pass pat MSR value directly.
> 
> This breaks xen as that function is used there, doh. :-\
> 
> Jürgen,
> 
> can you check the enlighten.c changes below please?
> 
> I'm reading xen's PAT config from MSR_IA32_CR_PAT and handing it down to
> pat_init_cache_modes(). That shouldn't change current behavior AFAICT
> because pat_init_cache_modes() did it itself before.
> 
> Right?
> 
> Thanks.
> 
> ---
> Author: Borislav Petkov <bp@...e.de>
> Date:   Sat May 30 13:09:55 2015 +0200
> 
>     x86/pat: Emulate PAT when it is disabled
>     
>     In the case when PAT is disabled on the command line with "nopat" or
>     when virtualization doesn't support PAT (correctly) - see
>     
>       9d34cfdf4796 ("x86: Don't rely on VMWare emulating PAT MSR correctly").
>     
>     we emulate it using the PWT and PCD cache attribute bits. Get rid of
>     boot_pat_state while at it.
>     
>     Based on a conglomerate patch from Toshi Kani.
>     
>     Signed-off-by: Borislav Petkov <bp@...e.de>

Reviewed-by: Toshi Kani <toshi.kani@...com>

Thanks,
-Toshi



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