context_tracking: Check static key on context_tracking_enabled_*cpu()

guest_enter() doesn't call context_tracking_enabled() before calling
context_tracking_enabled_this_cpu(). Therefore the guest code doesn't
benefit from the static key on the fast path.

Just make sure that context_tracking_enabled_*cpu() functions check
the static key by themselves to propagate the optimization.

Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J . Wysocki <rjw@rjwysocki.net>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Link: https://lkml.kernel.org/r/20191016025700.31277-11-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/linux/vtime.h b/include/linux/vtime.h
index e2733bf33541..2cdeca062db3 100644
--- a/include/linux/vtime.h
+++ b/include/linux/vtime.h
@@ -33,12 +33,12 @@ static inline bool vtime_accounting_enabled(void)
 
 static inline bool vtime_accounting_enabled_cpu(int cpu)
 {
-	return (vtime_accounting_enabled() && context_tracking_enabled_cpu(cpu));
+	return context_tracking_enabled_cpu(cpu);
 }
 
 static inline bool vtime_accounting_enabled_this_cpu(void)
 {
-	return (vtime_accounting_enabled() && context_tracking_enabled_this_cpu());
+	return context_tracking_enabled_this_cpu();
 }
 
 extern void vtime_task_switch_generic(struct task_struct *prev);