linux-kernel - Re: [PATCH v2 4/6] x86/mtrr: Fix PAT init handling when MTRR MSR is disabled

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Message-ID: <20160322170135.GE5656@pd.tnic>
Date:	Tue, 22 Mar 2016 18:01:35 +0100
From:	Borislav Petkov <bp@...e.de>
To:	Toshi Kani <toshi.kani@....com>
Cc:	mingo@...nel.org, hpa@...or.com, tglx@...utronix.de,
	mcgrof@...e.com, jgross@...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 4/6] x86/mtrr: Fix PAT init handling when MTRR MSR is
 disabled

Subject: [PATCH v2 4/6] x86/mtrr: Fix PAT init handling when MTRR MSR is disabled

s/ MSR//

On Wed, Mar 16, 2016 at 06:46:57PM -0600, Toshi Kani wrote:
> get_mtrr_state() calls pat_init() on BSP even if MTRR is disabled
> by its MSR.

s/by its MSR//

> This causes pat_init() to be called on BSP only since APs do not call

This doesn't cause that - get_mtrr_state() is called only on the BSP by
mtrr_bp_init().

> pat_init() when MTRR is disabled. This inconsistency between BSP and
> APs leads undefined behavior.

      leads to


> Move BSP's PAT init code from get_mtrr_state() to mtrr_bp_pat_init().
> Change mtrr_bp_init() to call mtrr_bp_pat_init() if MTRR is enabled.

No need for those.

> This keeps BSP's calling condition to pat_init() consistent with AP's,
> mtrr_ap_init() and mtrr_aps_init().

This one is fine.

-- 
Regards/Gruss,
    Boris.

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