perf/x86/intel: Support the 4 new OMR MSRs introduced in DMR and NVL

Diamond Rapids (DMR) and Nova Lake (NVL) introduce an enhanced
Off-Module Response (OMR) facility, replacing the Off-Core Response (OCR)
Performance Monitoring of previous processors.

Legacy microarchitectures used the OCR facility to evaluate off-core and
multi-core off-module transactions. The newly named OMR facility improves
OCR capabilities for scalable coverage of new memory systems in
multi-core module systems.

Similar to OCR, 4 additional off-module configuration MSRs
(OFFMODULE_RSP_0 to OFFMODULE_RSP_3) are introduced to specify attributes
of off-module transactions. When multiple identical OMR events are
created, they need to occupy the same OFFMODULE_RSP_x MSR. To ensure
these multiple identical OMR events can work simultaneously, the
intel_alt_er() and intel_fixup_er() helpers are enhanced to rotate these
OMR events across different OFFMODULE_RSP_* MSRs, similar to previous OCR
events.

For more details about OMR, please refer to section 16.1 "OFF-MODULE
 RESPONSE (OMR) FACILITY" in ISE documentation.

Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260114011750.350569-2-dapeng1.mi@linux.intel.com

Author: Dapeng Mi

arch/x86/events/intel/core.c

@@ -3532,34 +3532,59 @@ static int intel_alt_er(struct cpu_hw_events *cpuc,
 	struct extra_reg *extra_regs = hybrid(cpuc->pmu, extra_regs);
 	int alt_idx = idx;
 
-	if (!(x86_pmu.flags & PMU_FL_HAS_RSP_1))
-		return idx;
-
-	if (idx == EXTRA_REG_RSP_0)
-		alt_idx = EXTRA_REG_RSP_1;
+	switch (idx) {
+	case EXTRA_REG_RSP_0 ... EXTRA_REG_RSP_1:
+		if (!(x86_pmu.flags & PMU_FL_HAS_RSP_1))
+			return idx;
+		if (++alt_idx > EXTRA_REG_RSP_1)
+			alt_idx = EXTRA_REG_RSP_0;
+		if (config & ~extra_regs[alt_idx].valid_mask)
+			return idx;
+		break;
 
-	if (idx == EXTRA_REG_RSP_1)
-		alt_idx = EXTRA_REG_RSP_0;
+	case EXTRA_REG_OMR_0 ... EXTRA_REG_OMR_3:
+		if (!(x86_pmu.flags & PMU_FL_HAS_OMR))
+			return idx;
+		if (++alt_idx > EXTRA_REG_OMR_3)
+			alt_idx = EXTRA_REG_OMR_0;
+		/*
+		 * Subtracting EXTRA_REG_OMR_0 ensures to get correct
+		 * OMR extra_reg entries which start from 0.
+		 */
+		if (config & ~extra_regs[alt_idx - EXTRA_REG_OMR_0].valid_mask)
+			return idx;
+		break;
 
-	if (config & ~extra_regs[alt_idx].valid_mask)
-		return idx;
+	default:
+		break;
+	}
 
 	return alt_idx;
 }
 
 static void intel_fixup_er(struct perf_event *event, int idx)
 {
 	struct extra_reg *extra_regs = hybrid(event->pmu, extra_regs);
-	event->hw.extra_reg.idx = idx;
+	int er_idx;
 
-	if (idx == EXTRA_REG_RSP_0) {
-		event->hw.config &= ~INTEL_ARCH_EVENT_MASK;
-		event->hw.config |= extra_regs[EXTRA_REG_RSP_0].event;
-		event->hw.extra_reg.reg = MSR_OFFCORE_RSP_0;
-	} else if (idx == EXTRA_REG_RSP_1) {
+	event->hw.extra_reg.idx = idx;
+	switch (idx) {
+	case EXTRA_REG_RSP_0 ... EXTRA_REG_RSP_1:
+		er_idx = idx - EXTRA_REG_RSP_0;
 		event->hw.config &= ~INTEL_ARCH_EVENT_MASK;
-		event->hw.config |= extra_regs[EXTRA_REG_RSP_1].event;
-		event->hw.extra_reg.reg = MSR_OFFCORE_RSP_1;
+		event->hw.config |= extra_regs[er_idx].event;
+		event->hw.extra_reg.reg = MSR_OFFCORE_RSP_0 + er_idx;
+		break;
+
+	case EXTRA_REG_OMR_0 ... EXTRA_REG_OMR_3:
+		er_idx = idx - EXTRA_REG_OMR_0;
+		event->hw.config &= ~ARCH_PERFMON_EVENTSEL_UMASK;
+		event->hw.config |= 1ULL << (8 + er_idx);
+		event->hw.extra_reg.reg = MSR_OMR_0 + er_idx;
+		break;
+
+	default:
+		pr_warn("The extra reg idx %d is not supported.\n", idx);
 	}
 }
 

arch/x86/events/perf_event.h

@@ -45,6 +45,10 @@ enum extra_reg_type {
 	EXTRA_REG_FE		= 4,  /* fe_* */
 	EXTRA_REG_SNOOP_0	= 5,  /* snoop response 0 */
 	EXTRA_REG_SNOOP_1	= 6,  /* snoop response 1 */
+	EXTRA_REG_OMR_0		= 7,  /* OMR 0 */
+	EXTRA_REG_OMR_1		= 8,  /* OMR 1 */
+	EXTRA_REG_OMR_2		= 9,  /* OMR 2 */
+	EXTRA_REG_OMR_3		= 10,  /* OMR 3 */
 
 	EXTRA_REG_MAX		      /* number of entries needed */
 };
@@ -1099,6 +1103,7 @@ do {									\
 #define PMU_FL_RETIRE_LATENCY	0x200 /* Support Retire Latency in PEBS */
 #define PMU_FL_BR_CNTR		0x400 /* Support branch counter logging */
 #define PMU_FL_DYN_CONSTRAINT	0x800 /* Needs dynamic constraint */
+#define PMU_FL_HAS_OMR		0x1000 /* has 4 equivalent OMR regs */
 
 #define EVENT_VAR(_id)  event_attr_##_id
 #define EVENT_PTR(_id) &event_attr_##_id.attr.attr

arch/x86/include/asm/msr-index.h

@@ -263,6 +263,11 @@
 #define MSR_SNOOP_RSP_0			0x00001328
 #define MSR_SNOOP_RSP_1			0x00001329
 
+#define MSR_OMR_0			0x000003e0
+#define MSR_OMR_1			0x000003e1
+#define MSR_OMR_2			0x000003e2
+#define MSR_OMR_3			0x000003e3
+
 #define MSR_LBR_SELECT			0x000001c8
 #define MSR_LBR_TOS			0x000001c9