From 6e52499ecb74510ad00dcf15343c329052646509 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 17 Mar 2013 15:44:43 -0700 Subject: [PATCH] perf,x86: fix wrmsr_on_cpu() warning on suspend/resume commit 2a6e06b2aed6995af401dcd4feb5e79a0c7ea554 upstream. Commit 1d9d8639c063 ("perf,x86: fix kernel crash with PEBS/BTS after suspend/resume") fixed a crash when doing PEBS performance profiling after resuming, but in using init_debug_store_on_cpu() to restore the DS_AREA mtrr it also resulted in a new WARN_ON() triggering. init_debug_store_on_cpu() uses "wrmsr_on_cpu()", which in turn uses CPU cross-calls to do the MSR update. Which is not really valid at the early resume stage, and the warning is quite reasonable. Now, it all happens to _work_, for the simple reason that smp_call_function_single() ends up just doing the call directly on the CPU when the CPU number matches, but we really should just do the wrmsr() directly instead. This duplicates the wrmsr() logic, but hopefully we can just remove the wrmsr_on_cpu() version eventually. Reported-and-tested-by: Parag Warudkar Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- arch/x86/kernel/cpu/perf_event_intel_ds.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c index 41a7d21a098f..2d4e76ba2b5c 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_ds.c +++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c @@ -739,8 +739,10 @@ void intel_ds_init(void) void perf_restore_debug_store(void) { + struct debug_store *ds = __this_cpu_read(cpu_hw_events.ds); + if (!x86_pmu.bts && !x86_pmu.pebs) return; - init_debug_store_on_cpu(smp_processor_id()); + wrmsrl(MSR_IA32_DS_AREA, (unsigned long)ds); } -- 2.11.4.GIT