From: Andi Kleen <ak@linux.intel.com>
Date: Sun, 10 May 2015 19:22:46 +0000 (-0700)
Subject: perf/x86/intel/lbr: Optimize v4 LBR unfreezing
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=425507fa5f321bb5ce1b5eb57a9586e0cf0b9802;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

perf/x86/intel/lbr: Optimize v4 LBR unfreezing

In Arch perfmon v4 the GLOBAL_STATUS reset automatically unfreezes
LBRs. So no need to do it manually in the LBR code. Add a check
to skip it.

v2: Move test up to beginning of function.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: eranian@google.com
Link: http://lkml.kernel.org/r/1431285767-27027-9-git-send-email-andi@firstfloor.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
index 2fb57373beca..769a42f874dc 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c
@@ -140,6 +140,13 @@ static void __intel_pmu_lbr_enable(bool pmi)
 	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
 	u64 debugctl, lbr_select = 0, orig_debugctl;
 
+	/*
+	 * No need to unfreeze manually, as v4 can do that as part
+	 * of the GLOBAL_STATUS ack.
+	 */
+	if (pmi && x86_pmu.version >= 4)
+		return;
+
 	/*
 	 * No need to reprogram LBR_SELECT in a PMI, as it
 	 * did not change.