diff --git a/sys/x86/include/specialreg.h b/sys/x86/include/specialreg.h
index c9a1240e4033..ff6a7771c5fa 100644
--- a/sys/x86/include/specialreg.h
+++ b/sys/x86/include/specialreg.h
@@ -358,11 +358,45 @@
 #define	MSR_MC4_ADDR		0x412
 #define	MSR_MC4_MISC		0x413
 
+/*
+ * X2APIC MSRs
+ */
+#define	MSR_APIC_ID		0x802
+#define	MSR_APIC_VERSION	0x803
+#define	MSR_APIC_TPR		0x808
+#define	MSR_APIC_EOI		0x80b
+#define	MSR_APIC_LDR		0x80d
+#define	MSR_APIC_SVR		0x80f
+#define	MSR_APIC_ISR0		0x810
+#define	MSR_APIC_ISR1		0x811
+#define	MSR_APIC_ISR2		0x812
+#define	MSR_APIC_ISR3		0x813
+#define	MSR_APIC_ISR4		0x814
+#define	MSR_APIC_ISR5		0x815
+#define	MSR_APIC_ISR6		0x816
+#define	MSR_APIC_ISR7		0x817
+#define	MSR_APIC_TMR0		0x818
+#define	MSR_APIC_IRR0		0x820
+#define	MSR_APIC_ESR		0x828
+#define	MSR_APIC_LVT_CMCI	0x82F
+#define	MSR_APIC_ICR		0x830
+#define	MSR_APIC_LVT_TIMER	0x832
+#define	MSR_APIC_LVT_THERMAL	0x833
+#define	MSR_APIC_LVT_PCINT	0x834
+#define	MSR_APIC_LVT_LINT0	0x835
+#define	MSR_APIC_LVT_LINT1	0x836
+#define	MSR_APIC_LVT_ERROR	0x837
+#define	MSR_APIC_ICR_TIMER	0x838
+#define	MSR_APIC_CCR_TIMER	0x839
+#define	MSR_APIC_DCR_TIMER	0x83e
+#define	MSR_APIC_SELF_IPI	0x83f
+
 /*
  * Constants related to MSR's.
  */
-#define	APICBASE_RESERVED	0x000006ff
+#define	APICBASE_RESERVED	0x000002ff
 #define	APICBASE_BSP		0x00000100
+#define	APICBASE_X2APIC		0x00000400
 #define	APICBASE_ENABLED	0x00000800
 #define	APICBASE_ADDRESS	0xfffff000