Index: head/sys/dev/hyperv/vmbus/hv_et.c
===================================================================
--- head/sys/dev/hyperv/vmbus/hv_et.c
+++ head/sys/dev/hyperv/vmbus/hv_et.c
@@ -37,12 +37,17 @@
 #include <sys/time.h>
 #include <sys/timeet.h>
 
-#include "hv_vmbus_priv.h"
+#include <dev/hyperv/vmbus/hv_vmbus_priv.h>
+#include <dev/hyperv/vmbus/hyperv_reg.h>
 
 #define HV_TIMER_FREQUENCY		(10 * 1000 * 1000LL) /* 100ns period */
 #define HV_MAX_DELTA_TICKS		0xffffffffLL
 #define HV_MIN_DELTA_TICKS		1LL
 
+#define MSR_HV_STIMER0_CFG_SINT		\
+	((((uint64_t)HV_VMBUS_TIMER_SINT) << MSR_HV_STIMER_CFG_SINT_SHIFT) & \
+	 MSR_HV_STIMER_CFG_SINT_MASK)
+
 static struct eventtimer *et;
 
 static inline uint64_t
@@ -57,18 +62,15 @@
 static int
 hv_et_start(struct eventtimer *et, sbintime_t firsttime, sbintime_t periodtime)
 {
-	union hv_timer_config timer_cfg;
-	uint64_t current;
+	uint64_t current, config;
 
-	timer_cfg.as_uint64 = 0;
-	timer_cfg.auto_enable = 1;
-	timer_cfg.sintx = HV_VMBUS_TIMER_SINT;
+	config = MSR_HV_STIMER_CFG_AUTOEN | MSR_HV_STIMER0_CFG_SINT;
 
-	current = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
+	current = rdmsr(MSR_HV_TIME_REF_COUNT);
 	current += sbintime2tick(firsttime);
 
-	wrmsr(HV_X64_MSR_STIMER0_CONFIG, timer_cfg.as_uint64);
-	wrmsr(HV_X64_MSR_STIMER0_COUNT, current);
+	wrmsr(MSR_HV_STIMER0_CONFIG, config);
+	wrmsr(MSR_HV_STIMER0_COUNT, current);
 
 	return (0);
 }
@@ -76,8 +78,8 @@
 static int
 hv_et_stop(struct eventtimer *et)
 {
-	wrmsr(HV_X64_MSR_STIMER0_CONFIG, 0);
-	wrmsr(HV_X64_MSR_STIMER0_COUNT, 0);
+	wrmsr(MSR_HV_STIMER0_CONFIG, 0);
+	wrmsr(MSR_HV_STIMER0_COUNT, 0);
 
 	return (0);
 }
Index: head/sys/dev/hyperv/vmbus/hv_hv.c
===================================================================
--- head/sys/dev/hyperv/vmbus/hv_hv.c
+++ head/sys/dev/hyperv/vmbus/hv_hv.c
@@ -91,8 +91,7 @@
 static u_int
 hv_get_timecount(struct timecounter *tc)
 {
-	u_int now = rdmsr(HV_X64_MSR_TIME_REF_COUNT);
-	return (now);
+	return rdmsr(MSR_HV_TIME_REF_COUNT);
 }
 
 /**
Index: head/sys/dev/hyperv/vmbus/hyperv_reg.h
===================================================================
--- head/sys/dev/hyperv/vmbus/hyperv_reg.h
+++ head/sys/dev/hyperv/vmbus/hyperv_reg.h
@@ -54,6 +54,8 @@
 
 #define MSR_HV_VP_INDEX			0x40000002
 
+#define MSR_HV_TIME_REF_COUNT		0x40000020
+
 #define MSR_HV_SCONTROL			0x40000080
 #define MSR_HV_SCTRL_ENABLE		0x0001ULL
 #define MSR_HV_SCTRL_RSVD_MASK		0xfffffffffffffffeULL
@@ -77,6 +79,16 @@
 #define MSR_HV_SINT_RSVD_MASK		(MSR_HV_SINT_RSVD1_MASK |	\
 					 MSR_HV_SINT_RSVD2_MASK)
 
+#define MSR_HV_STIMER0_CONFIG		0x400000b0
+#define MSR_HV_STIMER_CFG_ENABLE	0x0001ULL
+#define MSR_HV_STIMER_CFG_PERIODIC	0x0002ULL
+#define MSR_HV_STIMER_CFG_LAZY		0x0004ULL
+#define MSR_HV_STIMER_CFG_AUTOEN	0x0008ULL
+#define MSR_HV_STIMER_CFG_SINT_MASK	0x000f0000ULL
+#define MSR_HV_STIMER_CFG_SINT_SHIFT	16
+
+#define MSR_HV_STIMER0_COUNT		0x400000b1
+
 /*
  * CPUID leaves
  */