Commit-ID:  ad025a73f0e9344ac73ffe1b74c184033e08e7d5
Gitweb:     http://git.kernel.org/tip/ad025a73f0e9344ac73ffe1b74c184033e08e7d5
Author:     Toshi Kani <toshi.k...@hpe.com>
AuthorDate: Wed, 23 Mar 2016 15:42:01 -0600
Committer:  Ingo Molnar <mi...@kernel.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.k...@hpe.com>
Reviewed-by: Thomas Gleixner <t...@linutronix.de>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Andy Lutomirski <l...@amacapital.net>
Cc: Borislav Petkov <b...@alien8.de>
Cc: Borislav Petkov <b...@suse.de>
Cc: Brian Gerst <brge...@gmail.com>
Cc: Denys Vlasenko <dvlas...@redhat.com>
Cc: H. Peter Anvin <h...@zytor.com>
Cc: Juergen Gross <jgr...@suse.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Luis R. Rodriguez <mcg...@suse.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Toshi Kani <toshi.k...@hp.com>
Cc: elli...@hpe.com
Cc: konrad.w...@oracle.com
Cc: paul.gortma...@windriver.com
Cc: xen-de...@lists.xenproject.org
Link: 
http://lkml.kernel.org/r/1458769323-24491-6-git-send-email-toshi.k...@hpe.com
Signed-off-by: Ingo Molnar <mi...@kernel.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);
 

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