perf/x86/ibs: Fix race with IBS_STARTING state
authorPeter Zijlstra <peterz@infradead.org>
Wed, 16 Mar 2016 22:55:21 +0000 (23:55 +0100)
committerIngo Molnar <mingo@kernel.org>
Mon, 21 Mar 2016 08:08:15 +0000 (09:08 +0100)
commit5a50f52917011365a4a2c0f1d2cea0990c4465cd
tree35a40bdf23e947e83caa3ebb5d3948e3ff72e69c
parent0158b83f7508851cda9e62c4b14678c5bd492cb2
perf/x86/ibs: Fix race with IBS_STARTING state

While tracing the IBS bits I saw the NMI hitting between clearing
IBS_STARTING and the actual MSR writes to disable the counter.

Since IBS_STARTING was cleared, the handler assumed these were spurious
NMIs and because STOPPING wasn't set yet either, insta-triggered an
"Unknown NMI".

Cure this by clearing IBS_STARTING after disabling the hardware.

Tested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/events/amd/ibs.c