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perf events fixes

GIT PULL Merged Ingo Molnar 2 participants 2 messages Oct 1, 2023

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x86 perf events
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Ingo Molnar

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Linus,

Please pull the latest perf/urgent git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git perf-urgent-2023-10-01

# HEAD: 599522d9d2e19d6240e4312577f1c5f3ffca22f6 perf/x86/amd: Do not WARN() on every IRQ

Misc fixes: work around an AMD microcode bug on certain models, and fix kexec kernel PMI handlers on AMD systems that get loaded on older kernels that have an unexpected register state.

Thanks,

Ingo

------------------>
Breno Leitao (1):
perf/x86/amd: Do not WARN() on every IRQ

Sandipan Das (1):
perf/x86/amd/core: Fix overflow reset on hotplug

 arch/x86/events/amd/core.c | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)
arch/x86/events/amd/core.c +17 -7
index abadd5f23425..e24976593a29 100644
@@ -534,8 +534,12 @@ static void amd_pmu_cpu_reset(int cpu)
 	/* Clear enable bits i.e. PerfCntrGlobalCtl.PerfCntrEn */
 	wrmsrl(MSR_AMD64_PERF_CNTR_GLOBAL_CTL, 0);
 
-	/* Clear overflow bits i.e. PerfCntrGLobalStatus.PerfCntrOvfl */
-	wrmsrl(MSR_AMD64_PERF_CNTR_GLOBAL_STATUS_CLR, amd_pmu_global_cntr_mask);
+	/*
+	 * Clear freeze and overflow bits i.e. PerfCntrGLobalStatus.LbrFreeze
+	 * and PerfCntrGLobalStatus.PerfCntrOvfl
+	 */
+	wrmsrl(MSR_AMD64_PERF_CNTR_GLOBAL_STATUS_CLR,
+	       GLOBAL_STATUS_LBRS_FROZEN | amd_pmu_global_cntr_mask);
 }
 
 static int amd_pmu_cpu_prepare(int cpu)

@@ -570,6 +574,7 @@ static void amd_pmu_cpu_starting(int cpu)
 	int i, nb_id;
 
 	cpuc->perf_ctr_virt_mask = AMD64_EVENTSEL_HOSTONLY;
+	amd_pmu_cpu_reset(cpu);
 
 	if (!x86_pmu.amd_nb_constraints)
 		return;

@@ -591,8 +596,6 @@ static void amd_pmu_cpu_starting(int cpu)
 
 	cpuc->amd_nb->nb_id = nb_id;
 	cpuc->amd_nb->refcnt++;
-
-	amd_pmu_cpu_reset(cpu);
 }
 
 static void amd_pmu_cpu_dead(int cpu)

@@ -601,6 +604,7 @@ static void amd_pmu_cpu_dead(int cpu)
 
 	kfree(cpuhw->lbr_sel);
 	cpuhw->lbr_sel = NULL;
+	amd_pmu_cpu_reset(cpu);
 
 	if (!x86_pmu.amd_nb_constraints)
 		return;

@@ -613,8 +617,6 @@ static void amd_pmu_cpu_dead(int cpu)
 
 		cpuhw->amd_nb = NULL;
 	}
-
-	amd_pmu_cpu_reset(cpu);
 }
 
 static inline void amd_pmu_set_global_ctl(u64 ctl)

@@ -884,7 +886,7 @@ static int amd_pmu_v2_handle_irq(struct pt_regs *regs)
 	struct hw_perf_event *hwc;
 	struct perf_event *event;
 	int handled = 0, idx;
-	u64 status, mask;
+	u64 reserved, status, mask;
 	bool pmu_enabled;
 
 	/*

@@ -909,6 +911,14 @@ static int amd_pmu_v2_handle_irq(struct pt_regs *regs)
 		status &= ~GLOBAL_STATUS_LBRS_FROZEN;
 	}
 
+	reserved = status & ~amd_pmu_global_cntr_mask;
+	if (reserved)
+		pr_warn_once("Reserved PerfCntrGlobalStatus bits are set (0x%llx), please consider updating microcode\n",
+			     reserved);
+
+	/* Clear any reserved bits set by buggy microcode */
+	status &= amd_pmu_global_cntr_mask;
+
 	for (idx = 0; idx < x86_pmu.num_counters; idx++) {
 		if (!test_bit(idx, cpuc->active_mask))
 			continue;