Commit-ID: e4557c1a46b0d32746bd309e1941914b5a6912b4
Gitweb: https://git.kernel.org/tip/e4557c1a46b0d32746bd309e1941914b5a6912b4
Author: Kan Liang <[email protected]>
AuthorDate: Tue, 25 Jun 2019 07:21:35 -0700
Committer: Ingo Molnar <[email protected]>
CommitDate: Sat, 13 Jul 2019 11:21:29 +0200
perf/x86/intel: Fix spurious NMI on fixed counter
If a user first sample a PEBS event on a fixed counter, then sample a
non-PEBS event on the same fixed counter on Icelake, it will trigger
spurious NMI. For example:
perf record -e 'cycles:p' -a
perf record -e 'cycles' -a
The error message for spurious NMI:
[June 21 15:38] Uhhuh. NMI received for unknown reason 30 on CPU 2.
[ +0.000000] Do you have a strange power saving mode enabled?
[ +0.000000] Dazed and confused, but trying to continue
The bug was introduced by the following commit:
commit 6f55967ad9d9 ("perf/x86/intel: Fix race in intel_pmu_disable_event()")
The commit moves the intel_pmu_pebs_disable() after intel_pmu_disable_fixed(),
which returns immediately. The related bit of PEBS_ENABLE MSR will never be
cleared for the fixed counter. Then a non-PEBS event runs on the fixed counter,
but the bit on PEBS_ENABLE is still set, which triggers spurious NMIs.
Check and disable PEBS for fixed counters after intel_pmu_disable_fixed().
Reported-by: Yi, Ammy <[email protected]>
Signed-off-by: Kan Liang <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Cc: <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vince Weaver <[email protected]>
Fixes: 6f55967ad9d9 ("perf/x86/intel: Fix race in intel_pmu_disable_event()")
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
arch/x86/events/intel/core.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index bda450ff51ee..9e911a96972b 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -2161,12 +2161,10 @@ static void intel_pmu_disable_event(struct perf_event
*event)
cpuc->intel_ctrl_host_mask &= ~(1ull << hwc->idx);
cpuc->intel_cp_status &= ~(1ull << hwc->idx);
- if (unlikely(hwc->config_base == MSR_ARCH_PERFMON_FIXED_CTR_CTRL)) {
+ if (unlikely(hwc->config_base == MSR_ARCH_PERFMON_FIXED_CTR_CTRL))
intel_pmu_disable_fixed(hwc);
- return;
- }
-
- x86_pmu_disable_event(event);
+ else
+ x86_pmu_disable_event(event);
/*
* Needs to be called after x86_pmu_disable_event,
