The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y git checkout FETCH_HEAD git cherry-pick -x a5f5e1238f4ff919816f69e77d2537a48911767b # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025042126-outgrow-kiln-e518@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From a5f5e1238f4ff919816f69e77d2537a48911767b Mon Sep 17 00:00:00 2001 From: Dapeng Mi dapeng1.mi@linux.intel.com Date: Tue, 15 Apr 2025 10:41:34 +0000 Subject: [PATCH] perf/x86/intel: Don't clear perf metrics overflow bit unconditionally
The below code would always unconditionally clear other status bits like perf metrics overflow bit once PEBS buffer overflows:
status &= intel_ctrl | GLOBAL_STATUS_TRACE_TOPAPMI;
This is incorrect. Perf metrics overflow bit should be cleared only when fixed counter 3 in PEBS counter group. Otherwise perf metrics overflow could be missed to handle.
Closes: https://lore.kernel.org/all/20250225110012.GK31462@noisy.programming.kicks-a... Fixes: 7b2c05a15d29 ("perf/x86/intel: Generic support for hardware TopDown metrics") Signed-off-by: Dapeng Mi dapeng1.mi@linux.intel.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Signed-off-by: Ingo Molnar mingo@kernel.org Reviewed-by: Kan Liang kan.liang@linux.intel.com Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250415104135.318169-1-dapeng1.mi@linux.intel.com
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index 09d2d66c9f21..2b70a3adde2f 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -3049,7 +3049,6 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status) struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); int bit; int handled = 0; - u64 intel_ctrl = hybrid(cpuc->pmu, intel_ctrl);
inc_irq_stat(apic_perf_irqs);
@@ -3093,7 +3092,6 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status) handled++; x86_pmu_handle_guest_pebs(regs, &data); static_call(x86_pmu_drain_pebs)(regs, &data); - status &= intel_ctrl | GLOBAL_STATUS_TRACE_TOPAPMI;
/* * PMI throttle may be triggered, which stops the PEBS event. @@ -3104,6 +3102,15 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status) */ if (pebs_enabled != cpuc->pebs_enabled) wrmsrl(MSR_IA32_PEBS_ENABLE, cpuc->pebs_enabled); + + /* + * Above PEBS handler (PEBS counters snapshotting) has updated fixed + * counter 3 and perf metrics counts if they are in counter group, + * unnecessary to update again. + */ + if (cpuc->events[INTEL_PMC_IDX_FIXED_SLOTS] && + is_pebs_counter_event_group(cpuc->events[INTEL_PMC_IDX_FIXED_SLOTS])) + status &= ~GLOBAL_STATUS_PERF_METRICS_OVF_BIT; }
/* @@ -3123,6 +3130,8 @@ static int handle_pmi_common(struct pt_regs *regs, u64 status) static_call(intel_pmu_update_topdown_event)(NULL, NULL); }
+ status &= hybrid(cpuc->pmu, intel_ctrl); + /* * Checkpointed counters can lead to 'spurious' PMIs because the * rollback caused by the PMI will have cleared the overflow status