linux-kernel - [PATCH 3/3] perf/x86/intel: Increase max number of the fixed counters

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Date:   Tue,  1 Feb 2022 13:23:23 -0800
From:   kan.liang@...ux.intel.com
To:     peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        linux-kernel@...r.kernel.org
Cc:     ak@...ux.intel.com, Kan Liang <kan.liang@...ux.intel.com>
Subject: [PATCH 3/3] perf/x86/intel: Increase max number of the fixed counters

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

The new PEBS format 5 implies that the number of the fixed counters can
be up to 16. The current INTEL_PMC_MAX_FIXED is still 4. If the current
kernel runs on a future platform which has more than 4 fixed counters,
a warning will be triggered. The number of the fixed counters will be
clipped to 4. Users have to upgrade the kernel to access the new fixed
counters.

Add a new default constraint for PerfMon v5 and up, which can support
up to 16 fixed counters. The pseudo-encoding is applied for the fixed
counters 4 and later. The user can have generic support for the new
fixed counters on the future platfroms without updating the kernel.

Increase the INTEL_PMC_MAX_FIXED to 16.

Reviewed-by: Andi Kleen <ak@...ux.intel.com>
Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
---
 arch/x86/events/intel/core.c      | 40 ++++++++++++++++++++++++++++++++++++++-
 arch/x86/include/asm/perf_event.h |  2 +-
 2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 46ac451..24a4a75 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -181,6 +181,27 @@ static struct event_constraint intel_gen_event_constraints[] __read_mostly =
 	EVENT_CONSTRAINT_END
 };
 
+static struct event_constraint intel_v5_gen_event_constraints[] __read_mostly =
+{
+	FIXED_EVENT_CONSTRAINT(0x00c0, 0), /* INST_RETIRED.ANY */
+	FIXED_EVENT_CONSTRAINT(0x003c, 1), /* CPU_CLK_UNHALTED.CORE */
+	FIXED_EVENT_CONSTRAINT(0x0300, 2), /* CPU_CLK_UNHALTED.REF */
+	FIXED_EVENT_CONSTRAINT(0x0400, 3), /* SLOTS */
+	FIXED_EVENT_CONSTRAINT(0x0500, 4),
+	FIXED_EVENT_CONSTRAINT(0x0600, 5),
+	FIXED_EVENT_CONSTRAINT(0x0700, 6),
+	FIXED_EVENT_CONSTRAINT(0x0800, 7),
+	FIXED_EVENT_CONSTRAINT(0x0900, 8),
+	FIXED_EVENT_CONSTRAINT(0x0a00, 9),
+	FIXED_EVENT_CONSTRAINT(0x0b00, 10),
+	FIXED_EVENT_CONSTRAINT(0x0c00, 11),
+	FIXED_EVENT_CONSTRAINT(0x0d00, 12),
+	FIXED_EVENT_CONSTRAINT(0x0e00, 13),
+	FIXED_EVENT_CONSTRAINT(0x0f00, 14),
+	FIXED_EVENT_CONSTRAINT(0x1000, 15),
+	EVENT_CONSTRAINT_END
+};
+
 static struct event_constraint intel_slm_event_constraints[] __read_mostly =
 {
 	FIXED_EVENT_CONSTRAINT(0x00c0, 0), /* INST_RETIRED.ANY */
@@ -6296,7 +6317,9 @@ __init int intel_pmu_init(void)
 			pr_cont("generic architected perfmon v1, ");
 			name = "generic_arch_v1";
 			break;
-		default:
+		case 2:
+		case 3:
+		case 4:
 			/*
 			 * default constraints for v2 and up
 			 */
@@ -6304,6 +6327,21 @@ __init int intel_pmu_init(void)
 			pr_cont("generic architected perfmon, ");
 			name = "generic_arch_v2+";
 			break;
+		default:
+			/*
+			 * The default constraints for v5 and up can support up to
+			 * 16 fixed counters. For the fixed counters 4 and later,
+			 * the pseudo-encoding is applied.
+			 * The constraints may be cut according to the CPUID enumeration
+			 * by inserting the EVENT_CONSTRAINT_END.
+			 */
+			if (x86_pmu.num_counters_fixed > INTEL_PMC_MAX_FIXED)
+				x86_pmu.num_counters_fixed = INTEL_PMC_MAX_FIXED;
+			intel_v5_gen_event_constraints[x86_pmu.num_counters_fixed].weight = -1;
+			x86_pmu.event_constraints = intel_v5_gen_event_constraints;
+			pr_cont("generic architected perfmon, ");
+			name = "generic_arch_v5+";
+			break;
 		}
 	}
 
diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index 8fc1b50..58d9e4b 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -7,7 +7,7 @@
  */
 
 #define INTEL_PMC_MAX_GENERIC				       32
-#define INTEL_PMC_MAX_FIXED					4
+#define INTEL_PMC_MAX_FIXED				       16
 #define INTEL_PMC_IDX_FIXED				       32
 
 #define X86_PMC_IDX_MAX					       64
-- 
2.7.4