linux-kernel - [tip:x86/fpu] x86/fpu: Get rid of two redundant clts() calls

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Date:   Tue, 1 Nov 2016 00:13:50 -0700
From:   tip-bot for Andy Lutomirski <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     kvm@...r.kernel.org, quentin.casasnovas@...cle.com,
        dave.hansen@...ux.intel.com, riel@...hat.com, jpoimboe@...hat.com,
        luto@...nel.org, torvalds@...ux-foundation.org,
        peterz@...radead.org, rusty@...tcorp.com.au, oleg@...hat.com,
        bp@...en8.de, brgerst@...il.com, linux-kernel@...r.kernel.org,
        mingo@...nel.org, tglx@...utronix.de, hpa@...or.com,
        dvlasenk@...hat.com, fenghua.yu@...el.com, pbonzini@...hat.com
Subject: [tip:x86/fpu] x86/fpu: Get rid of two redundant clts() calls

Commit-ID:  36fd4f0249f8cb445835acb7c6937a0ffa2b5f14
Gitweb:     http://git.kernel.org/tip/36fd4f0249f8cb445835acb7c6937a0ffa2b5f14
Author:     Andy Lutomirski <luto@...nel.org>
AuthorDate: Mon, 31 Oct 2016 15:18:42 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 1 Nov 2016 07:47:53 +0100

x86/fpu: Get rid of two redundant clts() calls

CR0.TS is cleared by a direct CR0 write in fpu__init_cpu_generic().
We don't need to call clts() two more times right after that.

Signed-off-by: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: Fenghua Yu <fenghua.yu@...el.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@...cle.com>
Cc: Rik van Riel <riel@...hat.com>
Cc: Rusty Russell <rusty@...tcorp.com.au>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: kvm list <kvm@...r.kernel.org>
Link: http://lkml.kernel.org/r/476d2d5066eda24838853426ea74c94140b50c85.1477951965.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/fpu/init.c | 18 ------------------
 1 file changed, 18 deletions(-)

diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index 1a09d13..60dece3 100644
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -10,15 +10,6 @@
 #include <linux/init.h>
 
 /*
- * Initialize the TS bit in CR0 according to the style of context-switches
- * we are using:
- */
-static void fpu__init_cpu_ctx_switch(void)
-{
-	clts();
-}
-
-/*
  * Initialize the registers found in all CPUs, CR0 and CR4:
  */
 static void fpu__init_cpu_generic(void)
@@ -55,7 +46,6 @@ void fpu__init_cpu(void)
 {
 	fpu__init_cpu_generic();
 	fpu__init_cpu_xstate();
-	fpu__init_cpu_ctx_switch();
 }
 
 /*
@@ -290,14 +280,6 @@ void __init fpu__init_system(struct cpuinfo_x86 *c)
 	 */
 	fpu__init_cpu();
 
-	/*
-	 * But don't leave CR0::TS set yet, as some of the FPU setup
-	 * methods depend on being able to execute FPU instructions
-	 * that will fault on a set TS, such as the FXSAVE in
-	 * fpu__init_system_mxcsr().
-	 */
-	clts();
-
 	fpu__init_system_generic();
 	fpu__init_system_xstate_size_legacy();
 	fpu__init_system_xstate();