linux-kernel - [tip:x86/urgent] x86/mm/32: Move setup_clear_cpu_cap(X86_FEATURE

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Message-ID: <tip-b8b7abaed7a49b350f8ba659ddc264b04931d581@git.kernel.org>
Date:   Sun, 17 Sep 2017 11:19:30 -0700
From:   tip-bot for Andy Lutomirski <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        mingo@...nel.org, hpa@...or.com, torvalds@...ux-foundation.org,
        bpetkov@...e.de, luto@...nel.org, tglx@...utronix.de
Subject: [tip:x86/urgent] x86/mm/32: Move
 setup_clear_cpu_cap(X86_FEATURE_PCID) earlier

Commit-ID:  b8b7abaed7a49b350f8ba659ddc264b04931d581
Gitweb:     http://git.kernel.org/tip/b8b7abaed7a49b350f8ba659ddc264b04931d581
Author:     Andy Lutomirski <luto@...nel.org>
AuthorDate: Sun, 17 Sep 2017 09:03:50 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Sun, 17 Sep 2017 18:59:08 +0200

x86/mm/32: Move setup_clear_cpu_cap(X86_FEATURE_PCID) earlier

Otherwise we might have the PCID feature bit set during cpu_init().

This is just for robustness.  I haven't seen any actual bugs here.

Signed-off-by: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bpetkov@...e.de>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Fixes: cba4671af755 ("x86/mm: Disable PCID on 32-bit kernels")
Link: http://lkml.kernel.org/r/b16dae9d6b0db5d9801ddbebbfd83384097c61f3.1505663533.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/cpu/bugs.c   | 8 --------
 arch/x86/kernel/cpu/common.c | 8 ++++++++
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index db68488..0af86d9 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -21,14 +21,6 @@
 
 void __init check_bugs(void)
 {
-#ifdef CONFIG_X86_32
-	/*
-	 * Regardless of whether PCID is enumerated, the SDM says
-	 * that it can't be enabled in 32-bit mode.
-	 */
-	setup_clear_cpu_cap(X86_FEATURE_PCID);
-#endif
-
 	identify_boot_cpu();
 
 	if (!IS_ENABLED(CONFIG_SMP)) {
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 775f101..c9176ba 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -904,6 +904,14 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
 
 	setup_force_cpu_cap(X86_FEATURE_ALWAYS);
 	fpu__init_system(c);
+
+#ifdef CONFIG_X86_32
+	/*
+	 * Regardless of whether PCID is enumerated, the SDM says
+	 * that it can't be enabled in 32-bit mode.
+	 */
+	setup_clear_cpu_cap(X86_FEATURE_PCID);
+#endif
 }
 
 void __init early_cpu_init(void)