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linux-stable/arch/x86/events
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Lendacky, Thomas 3966c3feca x86/perf/amd: Remove need to check "running" bit in NMI handler 
Spurious interrupt support was added to perf in the following commit, almost
a decade ago:

  63e6be6d98 ("perf, x86: Catch spurious interrupts after disabling counters")

The two previous patches (resolving the race condition when disabling a
PMC and NMI latency mitigation) allow for the removal of this older
spurious interrupt support.

Currently in x86_pmu_stop(), the bit for the PMC in the active_mask bitmap
is cleared before disabling the PMC, which sets up a race condition. This
race condition was mitigated by introducing the running bitmap. That race
condition can be eliminated by first disabling the PMC, waiting for PMC
reset on overflow and then clearing the bit for the PMC in the active_mask
bitmap. The NMI handler will not re-enable a disabled counter.

If x86_pmu_stop() is called from the perf NMI handler, the NMI latency
mitigation support will guard against any unhandled NMI messages.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org> # 4.14.x-
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: https://lkml.kernel.org/r/Message-ID:
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-04-10 13:03:18 +02:00
..
amd x86/perf/amd: Remove need to check "running" bit in NMI handler 2019-04-10 13:03:18 +02:00
intel perf/x86/intel: Initialize TFA MSR 2019-04-03 11:40:32 +02:00
core.c x86/perf/amd: Remove need to check "running" bit in NMI handler 2019-04-10 13:03:18 +02:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Makefile perf/x86/events: Add an AMD-specific Makefile 2017-01-30 12:01:19 +01:00
msr.c perf/core, arch/x86: Use PERF_PMU_CAP_NO_EXCLUDE for exclusion incapable PMUs 2019-01-21 11:01:27 +01:00
perf_event.h perf/x86: Fixup typo in stub functions 2019-03-15 13:12:42 +01:00