From 2a5bf23d5b795d5df33dc284e8f5cf8b6a5b4042 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 20 Nov 2018 18:08:42 +0100 Subject: [PATCH] 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 Signed-off-by: Peter Zijlstra (Intel) Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Kan Liang Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Robert O'Callahan Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Cc: acme@kernel.org Link: http://lkml.kernel.org/r/20181120170842.GZ2131@hirez.programming.kicks-ass.net Signed-off-by: Ingo Molnar --- 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: 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: -- 2.30.2