diff --git a/sys/platform/pc64/apic/lapic.c b/sys/platform/pc64/apic/lapic.c
index 255d96f..c789e9c 100644
--- a/sys/platform/pc64/apic/lapic.c
+++ b/sys/platform/pc64/apic/lapic.c
@@ -785,3 +785,75 @@ lapic_fixup_noioapic(void)
 	temp |= APIC_LVT_MASKED;
 	lapic->lvt_lint1 = temp;
 }
+
+#ifdef HWPMC_HOOKS
+void
+lapic_reenable_pmc(void)
+{
+	uint32_t value;
+	value = lapic->lvt_pcint;
+	value &= ~APIC_LVT_MASKED;
+	lapic->lvt_pcint = value;
+}
+
+static void
+lapic_enable_pmc_oncpu(void *dummy __unused)
+{
+	uint32_t value;
+	
+	value = lapic->lvt_pcint;
+	value &= ~(APIC_LVT_MASKED | APIC_LVT_TRIG_MASK | APIC_LVT_POLARITY_MASK |
+		   APIC_LVT_DM_MASK | APIC_LVT_VECTOR);
+	value |= APIC_LVT_DM_NMI | APIC_LVT_LEVELTRIG;
+	lapic->lvt_pcint = value;
+}
+
+int
+lapic_enable_pmc(void)
+{
+	/* XXX: need to check if lapic is initialized! */
+	/* XXX: we're optimistic and assume the PMC LVT is always available */
+#ifdef SMP
+	lwkt_cpusync_simple(-1, lapic_enable_pmc_oncpu, NULL);
+#else
+	lapic_enable_pmc_oncpu(NULL);
+#endif
+	return 1;
+}
+
+static void
+lapic_disable_pmc_oncpu(void *dummy __unused)
+{
+	uint32_t value;
+	value = lapic->lvt_pcint;
+	value |= APIC_LVT_MASKED;
+	lapic->lvt_pcint = value;
+}
+
+void
+lapic_disable_pmc(void)
+{
+#ifdef SMP
+	lwkt_cpusync_simple(-1, lapic_disable_pmc_oncpu, NULL);
+#else
+	lapic_disable_pmc_oncpu(NULL);
+#endif
+}
+
+#else	/* !HWPMC_HOOKS */
+void
+lapic_reenable_pmc(void)
+{
+}
+
+int
+lapic_enable_pmc(void)
+{
+	return 0;
+}
+
+void
+lapic_disable_pmc(void)
+{
+}
+#endif	/* HWPMC_HOOKS */