Index: sys/dev/hyperv/vmbus/hv_vmbus_drv_freebsd.c
===================================================================
--- sys/dev/hyperv/vmbus/hv_vmbus_drv_freebsd.c
+++ sys/dev/hyperv/vmbus/hv_vmbus_drv_freebsd.c
@@ -356,82 +356,9 @@
 	return (BUS_PROBE_DEFAULT);
 }
 
-#ifdef HYPERV
 extern inthand_t IDTVEC(rsvd), IDTVEC(hv_vmbus_callback);
 
 /**
- * @brief Find a free IDT slot and setup the interrupt handler.
- */
-static int
-vmbus_vector_alloc(void)
-{
-	int vector;
-	uintptr_t func;
-	struct gate_descriptor *ip;
-
-	/*
-	 * Search backwards form the highest IDT vector available for use
-	 * as vmbus channel callback vector. We install 'hv_vmbus_callback'
-	 * handler at that vector and use it to interrupt vcpus.
-	 */
-	vector = APIC_SPURIOUS_INT;
-	while (--vector >= APIC_IPI_INTS) {
-		ip = &idt[vector];
-		func = ((long)ip->gd_hioffset << 16 | ip->gd_looffset);
-		if (func == (uintptr_t)&IDTVEC(rsvd)) {
-#ifdef __i386__
-			setidt(vector , IDTVEC(hv_vmbus_callback), SDT_SYS386IGT,
-			    SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
-#else
-			setidt(vector , IDTVEC(hv_vmbus_callback), SDT_SYSIGT,
-			    SEL_KPL, 0);
-#endif
-
-			return (vector);
-		}
-	}
-	return (0);
-}
-
-/**
- * @brief Restore the IDT slot to rsvd.
- */
-static void
-vmbus_vector_free(int vector)
-{
-        uintptr_t func;
-        struct gate_descriptor *ip;
-
-	if (vector == 0)
-		return;
-
-        KASSERT(vector >= APIC_IPI_INTS && vector < APIC_SPURIOUS_INT,
-            ("invalid vector %d", vector));
-
-        ip = &idt[vector];
-        func = ((long)ip->gd_hioffset << 16 | ip->gd_looffset);
-        KASSERT(func == (uintptr_t)&IDTVEC(hv_vmbus_callback),
-            ("invalid vector %d", vector));
-
-        setidt(vector, IDTVEC(rsvd), SDT_SYSIGT, SEL_KPL, 0);
-}
-
-#else /* HYPERV */
-
-static int
-vmbus_vector_alloc(void)
-{
-	return(0);
-}
-
-static void
-vmbus_vector_free(int vector)
-{
-}
-
-#endif /* HYPERV */
-
-/**
  * @brief Main vmbus driver initialization routine.
  *
  * Here, we
@@ -466,23 +393,18 @@
 	/*
 	 * Find a free IDT slot for vmbus callback.
 	 */
-	hv_vmbus_g_context.hv_cb_vector = vmbus_vector_alloc();
-
-	if (hv_vmbus_g_context.hv_cb_vector == 0) {
-		if(bootverbose)
-			printf("Error VMBUS: Cannot find free IDT slot for "
-			    "vmbus callback!\n");
-		goto cleanup;
-	}
-
-	if(bootverbose)
-		printf("VMBUS: vmbus callback vector %d\n",
-		    hv_vmbus_g_context.hv_cb_vector);
+#ifdef __i386__
+	setidt(IDT_EVTCHN, IDTVEC(hv_vmbus_callback), SDT_SYS386IGT,
+		SEL_KPL, GSEL(GCODE_SEL, SEL_KPL));
+#else
+	setidt(IDT_EVTCHN, IDTVEC(hv_vmbus_callback), SDT_SYSIGT,
+		SEL_KPL, 0);
+#endif
 
 	/*
 	 * Notify the hypervisor of our vector.
 	 */
-	setup_args.vector = hv_vmbus_g_context.hv_cb_vector;
+	setup_args.vector = IDT_EVTCHN;
 
 	CPU_FOREACH(j) {
 		hv_vmbus_g_context.hv_msg_intr_event[j] = NULL;
@@ -583,9 +505,8 @@
 		hv_vmbus_g_context.hv_msg_intr_event[j] = NULL;	
 	}
 
-	vmbus_vector_free(hv_vmbus_g_context.hv_cb_vector);
+	setidt(IDT_EVTCHN, IDTVEC(rsvd), SDT_SYSIGT, SEL_KPL, 0);
 
-	cleanup:
 	hv_vmbus_cleanup();
 
 	return (ret);
@@ -652,7 +573,7 @@
 		hv_vmbus_g_context.hv_msg_intr_event[i] = NULL;	
 	}
 
-	vmbus_vector_free(hv_vmbus_g_context.hv_cb_vector);
+	setidt(IDT_EVTCHN, IDTVEC(rsvd), SDT_SYSIGT, SEL_KPL, 0);
 
 	return;
 }
Index: sys/dev/hyperv/vmbus/hv_vmbus_priv.h
===================================================================
--- sys/dev/hyperv/vmbus/hv_vmbus_priv.h
+++ sys/dev/hyperv/vmbus/hv_vmbus_priv.h
@@ -205,11 +205,6 @@
 	struct taskqueue		*hv_event_queue[MAXCPU];
 	struct intr_event		*hv_msg_intr_event[MAXCPU];
 	void				*msg_swintr[MAXCPU];
-	/*
-	 * Host use this vector to intrrupt guest for vmbus channel
-	 * event and msg.
-	 */
-	unsigned int			hv_cb_vector;
 } hv_vmbus_context;
 
 /*