linux-kernel - [tip:x86/pti] sched/smt: Expose sched_smt

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Date:   Wed, 28 Nov 2018 06:25:34 -0800
From:   tip-bot for Thomas Gleixner <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     tglx@...utronix.de, keescook@...omium.org,
        torvalds@...ux-foundation.org, asit.k.mallick@...el.com,
        david.c.stewart@...el.com, dave.hansen@...el.com,
        ak@...ux.intel.com, dwmw@...zon.co.uk, gregkh@...uxfoundation.org,
        thomas.lendacky@....com, tim.c.chen@...ux.intel.com,
        luto@...nel.org, longman9394@...il.com, casey.schaufler@...el.com,
        linux-kernel@...r.kernel.org, jpoimboe@...hat.com,
        peterz@...radead.org, jcm@...hat.com, jkosina@...e.cz,
        aarcange@...hat.com, arjan@...ux.intel.com, hpa@...or.com,
        mingo@...nel.org
Subject: [tip:x86/pti] sched/smt: Expose sched_smt_present static key

Commit-ID:  321a874a7ef85655e93b3206d0f36b4a6097f948
Gitweb:     https://git.kernel.org/tip/321a874a7ef85655e93b3206d0f36b4a6097f948
Author:     Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Sun, 25 Nov 2018 19:33:38 +0100
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Wed, 28 Nov 2018 11:57:07 +0100

sched/smt: Expose sched_smt_present static key

Make the scheduler's 'sched_smt_present' static key globaly available, so
it can be used in the x86 speculation control code.

Provide a query function and a stub for the CONFIG_SMP=n case.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Ingo Molnar <mingo@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Jiri Kosina <jkosina@...e.cz>
Cc: Tom Lendacky <thomas.lendacky@....com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: David Woodhouse <dwmw@...zon.co.uk>
Cc: Tim Chen <tim.c.chen@...ux.intel.com>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Casey Schaufler <casey.schaufler@...el.com>
Cc: Asit Mallick <asit.k.mallick@...el.com>
Cc: Arjan van de Ven <arjan@...ux.intel.com>
Cc: Jon Masters <jcm@...hat.com>
Cc: Waiman Long <longman9394@...il.com>
Cc: Greg KH <gregkh@...uxfoundation.org>
Cc: Dave Stewart <david.c.stewart@...el.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: stable@...r.kernel.org
Link: https://lkml.kernel.org/r/20181125185004.430168326@linutronix.de

---
 include/linux/sched/smt.h | 18 ++++++++++++++++++
 kernel/sched/sched.h      |  4 +---
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/include/linux/sched/smt.h b/include/linux/sched/smt.h
new file mode 100644
index 000000000000..c9e0be514110
--- /dev/null
+++ b/include/linux/sched/smt.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_SCHED_SMT_H
+#define _LINUX_SCHED_SMT_H
+
+#include <linux/static_key.h>
+
+#ifdef CONFIG_SCHED_SMT
+extern struct static_key_false sched_smt_present;
+
+static __always_inline bool sched_smt_active(void)
+{
+	return static_branch_likely(&sched_smt_present);
+}
+#else
+static inline bool sched_smt_active(void) { return false; }
+#endif
+
+#endif
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 618577fc9aa8..4e524ab589c9 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -23,6 +23,7 @@
 #include <linux/sched/prio.h>
 #include <linux/sched/rt.h>
 #include <linux/sched/signal.h>
+#include <linux/sched/smt.h>
 #include <linux/sched/stat.h>
 #include <linux/sched/sysctl.h>
 #include <linux/sched/task.h>
@@ -936,9 +937,6 @@ static inline int cpu_of(struct rq *rq)
 
 
 #ifdef CONFIG_SCHED_SMT
-
-extern struct static_key_false sched_smt_present;
-
 extern void __update_idle_core(struct rq *rq);
 
 static inline void update_idle_core(struct rq *rq)