perf/x86/intel: Don't disable "intel_bts" around "intel" event batching

At the moment, intel_bts events get disabled from intel PMU's disable
callback, which includes event scheduling transactions of said PMU,
which have nothing to do with intel_bts events.

We do want to keep intel_bts events off inside the PMI handler to
avoid filling up their buffer too soon.

This patch moves intel_bts enabling/disabling directly to the PMI
handler.

Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160915082233.11065-1-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 8 insertions, 7 deletions

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 2cbde2f449aa..4c9a79b9cd69 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -1730,9 +1730,11 @@ static __initconst const u64 knl_hw_cache_extra_regs
  * disabled state if called consecutively.
  *
  * During consecutive calls, the same disable value will be written to related
- * registers, so the PMU state remains unchanged. hw.state in
- * intel_bts_disable_local will remain PERF_HES_STOPPED too in consecutive
- * calls.
+ * registers, so the PMU state remains unchanged.
+ *
+ * intel_bts events don't coexist with intel PMU's BTS events because of
+ * x86_add_exclusive(x86_lbr_exclusive_lbr); there's no need to keep them
+ * disabled around intel PMU's event batching etc, only inside the PMI handler.
  */
 static void __intel_pmu_disable_all(void)
 {
@@ -1742,8 +1744,6 @@ static void __intel_pmu_disable_all(void)
 
         if (test_bit(INTEL_PMC_IDX_FIXED_BTS, cpuc->active_mask))
                 intel_pmu_disable_bts();
-        else
-                intel_bts_disable_local();
 
         intel_pmu_pebs_disable_all();
 }
@@ -1771,8 +1771,7 @@ static void __intel_pmu_enable_all(int added, bool pmi)
                         return;
 
                 intel_pmu_enable_bts(event->hw.config);
-        } else
-                intel_bts_enable_local();
+        }
 }
 
 static void intel_pmu_enable_all(int added)
@@ -2073,6 +2072,7 @@ static int intel_pmu_handle_irq(struct pt_regs *regs)
          */
         if (!x86_pmu.late_ack)
                 apic_write(APIC_LVTPC, APIC_DM_NMI);
+        intel_bts_disable_local();
         __intel_pmu_disable_all();
         handled = intel_pmu_drain_bts_buffer();
         handled += intel_bts_interrupt();
@@ -2172,6 +2172,7 @@ done:
         /* Only restore PMU state when it's active. See x86_pmu_disable(). */
         if (cpuc->enabled)
                 __intel_pmu_enable_all(0, true);
+        intel_bts_enable_local();
 
         /*
          * Only unmask the NMI after the overflow counters