linux-kernel - [tip:x86/mm] x86/mtrr: Fix PAT init handling when MTRR is disabled

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Message-ID: <tip-ad025a73f0e9344ac73ffe1b74c184033e08e7d5@git.kernel.org>
Date:	Tue, 29 Mar 2016 03:39:34 -0700
From:	tip-bot for Toshi Kani <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	toshi.kani@...com, peterz@...radead.org, mingo@...nel.org,
	torvalds@...ux-foundation.org, jgross@...e.com,
	linux-kernel@...r.kernel.org, mcgrof@...e.com, hpa@...or.com,
	bp@...e.de, luto@...capital.net, brgerst@...il.com,
	dvlasenk@...hat.com, tglx@...utronix.de, akpm@...ux-foundation.org,
	bp@...en8.de, toshi.kani@....com
Subject: [tip:x86/mm] x86/mtrr: Fix PAT init handling when MTRR is disabled

Commit-ID:  ad025a73f0e9344ac73ffe1b74c184033e08e7d5
Gitweb:     http://git.kernel.org/tip/ad025a73f0e9344ac73ffe1b74c184033e08e7d5
Author:     Toshi Kani <toshi.kani@....com>
AuthorDate: Wed, 23 Mar 2016 15:42:01 -0600
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 29 Mar 2016 12:23:26 +0200

x86/mtrr: Fix PAT init handling when MTRR is disabled

get_mtrr_state() calls pat_init() on BSP even if MTRR is disabled.
This results in calling pat_init() on BSP only since APs do not call
pat_init() when MTRR is disabled.  This inconsistency between BSP
and APs leads to undefined behavior.

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

Signed-off-by: Toshi Kani <toshi.kani@....com>
Reviewed-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Borislav Petkov <bp@...e.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Juergen Gross <jgross@...e.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Luis R. Rodriguez <mcgrof@...e.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Toshi Kani <toshi.kani@...com>
Cc: elliott@....com
Cc: konrad.wilk@...cle.com
Cc: paul.gortmaker@...driver.com
Cc: xen-devel@...ts.xenproject.org
Link: http://lkml.kernel.org/r/1458769323-24491-6-git-send-email-toshi.kani@hpe.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/cpu/mtrr/generic.c | 24 ++++++++++++++----------
 arch/x86/kernel/cpu/mtrr/main.c    |  3 +++
 arch/x86/kernel/cpu/mtrr/mtrr.h    |  1 +
 3 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index 19f5736..8d7a29e 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -444,11 +444,24 @@ static void __init print_mtrr_state(void)
 		pr_debug("TOM2: %016llx aka %lldM\n", mtrr_tom2, mtrr_tom2>>20);
 }
 
+/* PAT setup for BP. We need to go through sync steps here */
+void __init mtrr_bp_pat_init(void)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	prepare_set();
+
+	pat_init();
+
+	post_set();
+	local_irq_restore(flags);
+}
+
 /* Grab all of the MTRR state for this CPU into *state */
 bool __init get_mtrr_state(void)
 {
 	struct mtrr_var_range *vrs;
-	unsigned long flags;
 	unsigned lo, dummy;
 	unsigned int i;
 
@@ -481,15 +494,6 @@ bool __init get_mtrr_state(void)
 
 	mtrr_state_set = 1;
 
-	/* PAT setup for BP. We need to go through sync steps here */
-	local_irq_save(flags);
-	prepare_set();
-
-	pat_init();
-
-	post_set();
-	local_irq_restore(flags);
-
 	return !!(mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED);
 }
 
diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c
index 8b1947b..7d393ec 100644
--- a/arch/x86/kernel/cpu/mtrr/main.c
+++ b/arch/x86/kernel/cpu/mtrr/main.c
@@ -752,6 +752,9 @@ void __init mtrr_bp_init(void)
 			/* BIOS may override */
 			__mtrr_enabled = get_mtrr_state();
 
+			if (mtrr_enabled())
+				mtrr_bp_pat_init();
+
 			if (mtrr_cleanup(phys_addr)) {
 				changed_by_mtrr_cleanup = 1;
 				mtrr_if->set_all();
diff --git a/arch/x86/kernel/cpu/mtrr/mtrr.h b/arch/x86/kernel/cpu/mtrr/mtrr.h
index 951884d..6c7ced0 100644
--- a/arch/x86/kernel/cpu/mtrr/mtrr.h
+++ b/arch/x86/kernel/cpu/mtrr/mtrr.h
@@ -52,6 +52,7 @@ void set_mtrr_prepare_save(struct set_mtrr_context *ctxt);
 void fill_mtrr_var_range(unsigned int index,
 		u32 base_lo, u32 base_hi, u32 mask_lo, u32 mask_hi);
 bool get_mtrr_state(void);
+void mtrr_bp_pat_init(void);
 
 extern void set_mtrr_ops(const struct mtrr_ops *ops);