diff --git a/sys/x86/include/specialreg.h b/sys/x86/include/specialreg.h
--- a/sys/x86/include/specialreg.h
+++ b/sys/x86/include/specialreg.h
@@ -345,6 +345,13 @@
 /* Ecx. */
 #define	CPUID_PERF_STAT			0x00000001
 #define	CPUID_PERF_BIAS			0x00000008
+#define	CPUID_PERF_TD_CLASSES		0x0000ff00
+
+/* Edx. */
+#define	CPUID_HF_PERFORMANCE		0x00000001
+#define	CPUID_HF_EFFICIENCY		0x00000002
+#define	CPUID_TD_CAPABLITIES		0x0000000f
+#define	CPUID_TD_TBLPAGES		0x00000f00
 
 /* 
  * CPUID instruction 0xb ebx info.
@@ -583,6 +590,8 @@
 #define	MSR_TURBO_RATIO_LIMIT	0x1ad
 #define	MSR_TURBO_RATIO_LIMIT1	0x1ae
 #define	MSR_IA32_ENERGY_PERF_BIAS	0x1b0
+#define	MSR_IA32_PKG_THERM_STATUS	0x1b1
+#define	MSR_IA32_PKG_THERM_INTERRUPT	0x1b2
 #define	MSR_DEBUGCTLMSR		0x1d9
 #define	MSR_LASTBRANCHFROMIP	0x1db
 #define	MSR_LASTBRANCHTOIP	0x1dc
@@ -766,6 +775,14 @@
 #define	TOPA_INT	(1 << 2)
 #define	TOPA_END	(1 << 0)
 
+/*
+ *  Intel Hardware Feedback Interface / Thread Director MSRs
+ */
+#define	MSR_IA32_HW_FEEDBACK_PTR		0x17d0
+#define	MSR_IA32_HW_FEEDBACK_CONFIG		0x17d1
+#define	MSR_IA32_THREAD_FEEDBACK_CHAR		0x17d2
+#define	MSR_IA32_HW_FEEDBACK_THREAD_CONFIG	0x17d4
+
 /*
  * Constants related to MSR's.
  */
@@ -836,6 +853,19 @@
 /* MSR IA32_ENERGY_PERF_BIAS */
 #define	IA32_ENERGY_PERF_BIAS_POLICY_HINT_MASK		(0xfULL << 0)
 
+/* MSR IA32_HW_FEEDBACK_PTR */
+#define	IA32_HW_FEEDBACK_PTR_ENABLE			(0x1ULL << 0)
+
+/* MSR IA32_HW_FEEDBACK_CONFIG */
+#define	IA32_HW_FEEDBACK_CONFIG_EN_HFI			(0x1ULL << 0)
+#define	IA32_HW_FEEDBACK_CONFIG_EN_THDIR		(0x1ULL << 1)
+
+/* MSR IA32_PKG_THERM_STATUS */
+#define	IA32_PKG_THERM_STATUS_HFI_UPDATED		(0x1ULL << 26)
+
+/* MSR IA32_PKG_THERM_INTERRUPT */
+#define	IA32_PKG_THERM_INTERRUPT_HFI_ENABLE		(0x1ULL << 25)
+
 /*
  * PAT modes.
  */