perf/x86/intel: Factor out intel_pmu_check_extra_regs

Each Hybrid PMU has to check and update its own extra registers before
registration.

The intel_pmu_check_extra_regs will be reused later to check the extra
registers of each hybrid PMU.
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Link: https://lkml.kernel.org/r/1618237865-33448-14-git-send-email-kan.liang@linux.intel.com

arch/x86/events/intel/core.c

@@ -5127,6 +5127,26 @@ static void intel_pmu_check_event_constraints(struct event_constraint *event_con
 	}
 }
 
+static void intel_pmu_check_extra_regs(struct extra_reg *extra_regs)
+{
+	struct extra_reg *er;
+
+	/*
+	 * Access extra MSR may cause #GP under certain circumstances.
+	 * E.g. KVM doesn't support offcore event
+	 * Check all extra_regs here.
+	 */
+	if (!extra_regs)
+		return;
+
+	for (er = extra_regs; er->msr; er++) {
+		er->extra_msr_access = check_msr(er->msr, 0x11UL);
+		/* Disable LBR select mapping */
+		if ((er->idx == EXTRA_REG_LBR) && !er->extra_msr_access)
+			x86_pmu.lbr_sel_map = NULL;
+	}
+}
+
 __init int intel_pmu_init(void)
 {
 	struct attribute **extra_skl_attr = &empty_attrs;
@@ -5138,7 +5158,6 @@ __init int intel_pmu_init(void)
 	union cpuid10_eax eax;
 	union cpuid10_ebx ebx;
 	unsigned int fixed_mask;
-	struct extra_reg *er;
 	bool pmem = false;
 	int version, i;
 	char *name;
@@ -5795,19 +5814,7 @@ __init int intel_pmu_init(void)
 	if (x86_pmu.lbr_nr)
 		pr_cont("%d-deep LBR, ", x86_pmu.lbr_nr);
 
-	/*
-	 * Access extra MSR may cause #GP under certain circumstances.
-	 * E.g. KVM doesn't support offcore event
-	 * Check all extra_regs here.
-	 */
-	if (x86_pmu.extra_regs) {
-		for (er = x86_pmu.extra_regs; er->msr; er++) {
-			er->extra_msr_access = check_msr(er->msr, 0x11UL);
-			/* Disable LBR select mapping */
-			if ((er->idx == EXTRA_REG_LBR) && !er->extra_msr_access)
-				x86_pmu.lbr_sel_map = NULL;
-		}
-	}
+	intel_pmu_check_extra_regs(x86_pmu.extra_regs);
 
 	/* Support full width counters using alternative MSR range */
 	if (x86_pmu.intel_cap.full_width_write) {