linux-kernel - [PATCH V2 3/3] perf/x86/intel: Add quirk for Goldmont Plus

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Date:   Wed,  8 Aug 2018 00:12:08 -0700
From:   kan.liang@...ux.intel.com
To:     peterz@...radead.org, tglx@...utronix.de, mingo@...hat.com,
        acme@...nel.org, linux-kernel@...r.kernel.org
Cc:     eranian@...gle.com, ak@...ux.intel.com,
        alexander.shishkin@...ux.intel.com,
        Kan Liang <kan.liang@...ux.intel.com>
Subject: [PATCH V2 3/3] perf/x86/intel: Add quirk for Goldmont Plus

From: Kan Liang <kan.liang@...ux.intel.com>

A ucode patch is needed for Goldmont Plus while counter freezing feature
is enabled. Otherwise, there will be some issues, e.g. PMI flood with
some events.

Add a quirk to check microcode version. If the system starts with the
wrong ucode, leave the counter-freezing feature permanently disabled.

Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
---

Changes since V1:
 - Only check the microcode version on CPU 0 at initialization.

 arch/x86/events/intel/core.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index fdd2f99..928a393 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -3839,6 +3839,42 @@ static __init void intel_nehalem_quirk(void)
 	}
 }
 
+static bool intel_glp_counter_freezing_broken(int cpu)
+{
+	u32 rev = UINT_MAX; /* default to broken for unknown stepping */
+
+	switch (cpu_data(cpu).x86_stepping) {
+	case 1:
+		rev = 0x28;
+		break;
+	case 8:
+		rev = 0x6;
+		break;
+	}
+
+	return (cpu_data(cpu).microcode < rev);
+}
+
+static __init void intel_glp_counter_freezing_quirk(void)
+{
+	/* Check if it's already disabled */
+	if (disable_counter_freezing)
+		return;
+
+	/*
+	 * If the system starts with the wrong ucode, leave the
+	 * counter-freezing feature permanently disabled.
+	 * Only checking one CPU is enough. When perf first initializes,
+	 * only CPU 0 is online.
+	 */
+	if (intel_glp_counter_freezing_broken(0)) {
+		pr_info("PMU counter freezing disabled due to CPU errata,"
+			"please upgrade microcode\n");
+		x86_pmu.counter_freezing = false;
+		x86_pmu.handle_irq = intel_pmu_handle_irq;
+	}
+}
+
 /*
  * enable software workaround for errata:
  * SNB: BJ122
@@ -4183,6 +4219,7 @@ __init int intel_pmu_init(void)
 		break;
 
 	case INTEL_FAM6_ATOM_GOLDMONT_PLUS:
+		x86_add_quirk(intel_glp_counter_freezing_quirk);
 		memcpy(hw_cache_event_ids, glp_hw_cache_event_ids,
 		       sizeof(hw_cache_event_ids));
 		memcpy(hw_cache_extra_regs, glp_hw_cache_extra_regs,
@@ -4199,6 +4236,8 @@ __init int intel_pmu_init(void)
 		x86_pmu.pebs_aliases = NULL;
 		x86_pmu.pebs_prec_dist = true;
 		x86_pmu.lbr_pt_coexist = true;
+		x86_pmu.counter_freezing = disable_counter_freezing ?
+					   false : true;
 		x86_pmu.flags |= PMU_FL_HAS_RSP_1;
 		x86_pmu.flags |= PMU_FL_PEBS_ALL;
 		x86_pmu.get_event_constraints = glp_get_event_constraints;
-- 
2.7.4