Commit-ID: 2a5bf23d5b795d5df33dc284e8f5cf8b6a5b4042
Gitweb: https://git.kernel.org/tip/2a5bf23d5b795d5df33dc284e8f5cf8b6a5b4042
Author: Peter Zijlstra <pet...@infradead.org>
AuthorDate: Tue, 20 Nov 2018 18:08:42 +0100
Committer: Ingo Molnar <mi...@kernel.org>
CommitDate: Tue, 20 Nov 2018 18:57:48 +0100
perf/x86/intel: Fix regression by default disabling perfmon v4 interrupt
handling
Kyle Huey reported that 'rr', a replay debugger, broke due to the following
commit:
af3bdb991a5c ("perf/x86/intel: Add a separate Arch Perfmon v4 PMI handler")
Rework the 'disable_counter_freezing' __setup() parameter such that we
can explicitly enable/disable it and switch to default disabled.
To this purpose, rename the parameter to "perf_v4_pmi=" which is a much
better description and allows requiring a bool argument.
[ mingo: Improved the changelog some more. ]
Reported-by: Kyle Huey <m...@kylehuey.com>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Cc: Alexander Shishkin <alexander.shish...@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <a...@redhat.com>
Cc: Jiri Olsa <jo...@redhat.com>
Cc: Kan Liang <kan.li...@linux.intel.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Robert O'Callahan <rob...@ocallahan.org>
Cc: Stephane Eranian <eran...@google.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Vince Weaver <vincent.wea...@maine.edu>
Cc: a...@kernel.org
Link:
http://lkml.kernel.org/r/20181120170842.gz2...@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mi...@kernel.org>
---
Documentation/admin-guide/kernel-parameters.txt | 3 ++-
arch/x86/events/intel/core.c | 12 ++++++++----
2 files changed, 10 insertions(+), 5 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt
b/Documentation/admin-guide/kernel-parameters.txt
index 81d1d5a74728..5463d5a4d85c 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -856,7 +856,8 @@
causing system reset or hang due to sending
INIT from AP to BSP.
- disable_counter_freezing [HW]
+ perf_v4_pmi= [X86,INTEL]
+ Format: <bool>
Disable Intel PMU counter freezing feature.
The feature only exists starting from
Arch Perfmon v4 (Skylake and newer).
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 273c62e81546..af8bea9d4006 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -2306,14 +2306,18 @@ static int handle_pmi_common(struct pt_regs *regs, u64
status)
return handled;
}
-static bool disable_counter_freezing;
+static bool disable_counter_freezing = true;
static int __init intel_perf_counter_freezing_setup(char *s)
{
- disable_counter_freezing = true;
- pr_info("Intel PMU Counter freezing feature disabled\n");
+ bool res;
+
+ if (kstrtobool(s, &res))
+ return -EINVAL;
+
+ disable_counter_freezing = !res;
return 1;
}
-__setup("disable_counter_freezing", intel_perf_counter_freezing_setup);
+__setup("perf_v4_pmi=", intel_perf_counter_freezing_setup);
/*
* Simplified handler for Arch Perfmon v4:
