Index: head/sys/dev/hyperv/include/hyperv.h
===================================================================
--- head/sys/dev/hyperv/include/hyperv.h
+++ head/sys/dev/hyperv/include/hyperv.h
@@ -523,12 +523,13 @@
 	hv_vmbus_channel_state		state;
 	uint32_t			ch_flags;	/* VMBUS_CHAN_FLAG_ */
 	uint32_t			ch_id;		/* channel id */
+
 	/*
 	 * These are based on the offer_msg.monitor_id.
 	 * Save it here for easy access.
 	 */
-	uint8_t				monitor_group;
-	uint8_t				monitor_bit;
+	int				ch_montrig_idx;	/* MNF trig index */
+	uint32_t			ch_montrig_mask;/* MNF trig mask */
 
 	uint32_t			ring_buffer_gpadl_handle;
 	/*
Index: head/sys/dev/hyperv/vmbus/hv_channel.c
===================================================================
--- head/sys/dev/hyperv/vmbus/hv_channel.c
+++ head/sys/dev/hyperv/vmbus/hv_channel.c
@@ -50,7 +50,7 @@
 #include <dev/hyperv/vmbus/vmbus_reg.h>
 #include <dev/hyperv/vmbus/vmbus_var.h>
 
-static void 	vmbus_channel_set_event(hv_vmbus_channel* channel);
+static void 	vmbus_chan_send_event(hv_vmbus_channel* channel);
 static void	vmbus_chan_update_evtflagcnt(struct vmbus_softc *,
 		    const struct hv_vmbus_channel *);
 static void	vmbus_chan_task(void *, int);
@@ -60,7 +60,7 @@
  *  @brief Trigger an event notification on the specified channel
  */
 static void
-vmbus_channel_set_event(hv_vmbus_channel *channel)
+vmbus_chan_send_event(hv_vmbus_channel *channel)
 {
 	struct vmbus_softc *sc = channel->vmbus_sc;
 	uint32_t chanid = channel->ch_id;
@@ -69,16 +69,12 @@
 	    1UL << (chanid & VMBUS_EVTFLAG_MASK));
 
 	if (channel->ch_flags & VMBUS_CHAN_FLAG_HASMNF) {
-		hv_vmbus_monitor_page *monitor_page;
-
-		monitor_page = sc->vmbus_mnf2;
-		synch_set_bit(channel->monitor_bit,
-			(uint32_t *)&monitor_page->
-				trigger_group[channel->monitor_group].u.pending);
+		atomic_set_int(
+		&sc->vmbus_mnf2->mnf_trigs[channel->ch_montrig_idx].mt_pending,
+		channel->ch_montrig_mask);
 	} else {
 		hypercall_signal_event(channel->ch_monprm_dma.hv_paddr);
 	}
-
 }
 
 static int
@@ -622,9 +618,8 @@
 	    &need_sig);
 
 	/* TODO: We should determine if this is optional */
-	if (ret == 0 && need_sig) {
-		vmbus_channel_set_event(channel);
-	}
+	if (ret == 0 && need_sig)
+		vmbus_chan_send_event(channel);
 
 	return (ret);
 }
@@ -690,9 +685,8 @@
 	    &need_sig);
 
 	/* TODO: We should determine if this is optional */
-	if (ret == 0 && need_sig) {
-		vmbus_channel_set_event(channel);
-	}
+	if (ret == 0 && need_sig)
+		vmbus_chan_send_event(channel);
 
 	return (ret);
 }
@@ -766,9 +760,8 @@
 	    &need_sig);
 
 	/* TODO: We should determine if this is optional */
-	if (ret == 0 && need_sig) {
-	    vmbus_channel_set_event(channel);
-	}
+	if (ret == 0 && need_sig)
+		vmbus_chan_send_event(channel);
 
 	return (ret);
 }
Index: head/sys/dev/hyperv/vmbus/hv_channel_mgmt.c
===================================================================
--- head/sys/dev/hyperv/vmbus/hv_channel_mgmt.c
+++ head/sys/dev/hyperv/vmbus/hv_channel_mgmt.c
@@ -311,8 +311,14 @@
 	if (sc->vmbus_version != VMBUS_VERSION_WS2008)
 		new_channel->ch_monprm->mp_connid = offer->connection_id;
 
-	new_channel->monitor_group = (uint8_t) offer->monitor_id / 32;
-	new_channel->monitor_bit = (uint8_t) offer->monitor_id % 32;
+	if (new_channel->ch_flags & VMBUS_CHAN_FLAG_HASMNF) {
+		new_channel->ch_montrig_idx =
+		    offer->monitor_id / VMBUS_MONTRIG_LEN;
+		if (new_channel->ch_montrig_idx >= VMBUS_MONTRIGS_MAX)
+			panic("invalid monitor id %u", offer->monitor_id);
+		new_channel->ch_montrig_mask =
+		    1 << (offer->monitor_id % VMBUS_MONTRIG_LEN);
+	}
 
 	/* Select default cpu for this channel. */
 	vmbus_channel_select_defcpu(new_channel);
Index: head/sys/dev/hyperv/vmbus/vmbus.c
===================================================================
--- head/sys/dev/hyperv/vmbus/vmbus.c
+++ head/sys/dev/hyperv/vmbus/vmbus.c
@@ -835,7 +835,8 @@
 		return ENOMEM;
 
 	sc->vmbus_mnf2 = hyperv_dmamem_alloc(parent_dtag, PAGE_SIZE, 0,
-	    PAGE_SIZE, &sc->vmbus_mnf2_dma, BUS_DMA_WAITOK | BUS_DMA_ZERO);
+	    sizeof(struct vmbus_mnf), &sc->vmbus_mnf2_dma,
+	    BUS_DMA_WAITOK | BUS_DMA_ZERO);
 	if (sc->vmbus_mnf2 == NULL)
 		return ENOMEM;
 
Index: head/sys/dev/hyperv/vmbus/vmbus_reg.h
===================================================================
--- head/sys/dev/hyperv/vmbus/vmbus_reg.h
+++ head/sys/dev/hyperv/vmbus/vmbus_reg.h
@@ -72,6 +72,34 @@
 CTASSERT(sizeof(struct vmbus_evtflags) == VMBUS_EVTFLAGS_SIZE);
 
 /*
+ * Hyper-V Monitor Notification Facility
+ */
+
+struct vmbus_mon_trig {
+	uint32_t	mt_pending;
+	uint32_t	mt_armed;
+} __packed;
+
+#define VMBUS_MONTRIGS_MAX	4
+#define VMBUS_MONTRIG_LEN	32
+
+struct vmbus_mnf {
+	uint32_t	mnf_state;
+	uint32_t	mnf_rsvd1;
+
+	struct vmbus_mon_trig mnf_trigs[VMBUS_MONTRIGS_MAX];
+	uint8_t		mnf_rsvd2[536];
+
+	uint16_t	mnf_lat[VMBUS_MONTRIGS_MAX][VMBUS_MONTRIG_LEN];
+	uint8_t		mnf_rsvd3[256];
+
+	struct hyperv_mon_param
+			mnf_param[VMBUS_MONTRIGS_MAX][VMBUS_MONTRIG_LEN];
+	uint8_t		mnf_rsvd4[1984];
+} __packed;
+CTASSERT(sizeof(struct vmbus_mnf) == PAGE_SIZE);
+
+/*
  * Channel
  */
 
Index: head/sys/dev/hyperv/vmbus/vmbus_var.h
===================================================================
--- head/sys/dev/hyperv/vmbus/vmbus_var.h
+++ head/sys/dev/hyperv/vmbus/vmbus_var.h
@@ -71,7 +71,7 @@
 	void			(*vmbus_event_proc)(struct vmbus_softc *, int);
 	u_long			*vmbus_tx_evtflags;
 						/* event flags to host */
-	void			*vmbus_mnf2;	/* monitored by host */
+	struct vmbus_mnf	*vmbus_mnf2;	/* monitored by host */
 
 	u_long			*vmbus_rx_evtflags;
 						/* compat evtflgs from host */