linux-kernel - Re: [PATCH v2 5/6] x86/xen,pat: Remove PAT table init code from Xen

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Date:	Tue, 22 Mar 2016 18:02:06 +0100
From:	Borislav Petkov <bp@...e.de>
To:	Toshi Kani <toshi.kani@....com>, jgross@...e.com
Cc:	mingo@...nel.org, hpa@...or.com, tglx@...utronix.de,
	mcgrof@...e.com, paul.gortmaker@...driver.com,
	konrad.wilk@...cle.com, elliott@....com, x86@...nel.org,
	xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 5/6] x86/xen,pat: Remove PAT table init code from Xen

On Wed, Mar 16, 2016 at 06:46:58PM -0600, Toshi Kani wrote:
> Xen supports PAT without MTRR for its guests.  In order to
> enable WC attribute, it was necessary for xen_start_kernel()
> to call pat_init_cache_modes() to update PAT table before
> starting guest kernel.
> 
> Now that the kernel initializes PAT table to the BIOS handoff
> state when MTRR is disabled, this Xen-specific PAT init code
> is no longer necessary.  Delete it from xen_start_kernel().
> 
> Also change pat_init_cache_modes() to a static function since
> PAT table should not be tweaked by other modules.
> 
> Signed-off-by: Toshi Kani <toshi.kani@....com>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> Cc: Borislav Petkov <bp@...e.de>
> Cc: Luis R. Rodriguez <mcgrof@...e.com>
> Cc: Juergen Gross <jgross@...e.com>
> Cc: Ingo Molnar <mingo@...nel.org>
> Cc: H. Peter Anvin <hpa@...or.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> ---
>  arch/x86/include/asm/pat.h |    1 -
>  arch/x86/mm/pat.c          |    2 +-
>  arch/x86/xen/enlighten.c   |    9 ---------
>  3 files changed, 1 insertion(+), 11 deletions(-)

Jürgen, ack?

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--