Commit 023e9deb authored Oct 16, 2019 by Frederic Weisbecker Committed by Ingo Molnar Oct 29, 2019

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>

parent 9adbb9dd

include/linux/context_tracking_state.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -33,12 +33,12 @@ static inline bool context_tracking_enabled(void)

		static inline bool context_tracking_enabled_cpu(int cpu)
		{
		return per_cpu(context_tracking.active, cpu);
		return context_tracking_enabled() && per_cpu(context_tracking.active, cpu);
		}

		static inline bool context_tracking_enabled_this_cpu(void)
		{
		return __this_cpu_read(context_tracking.active);
		return context_tracking_enabled() && __this_cpu_read(context_tracking.active);
		}

		static inline bool context_tracking_in_user(void)

include/linux/vtime.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -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);

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