Index: head/sys/dev/hyperv/netvsc/hv_net_vsc.c
===================================================================
--- head/sys/dev/hyperv/netvsc/hv_net_vsc.c
+++ head/sys/dev/hyperv/netvsc/hv_net_vsc.c
@@ -102,7 +102,7 @@
 	return (ret);
 }
 
-const void *
+static const void *
 hn_nvs_xact_execute(struct hn_softc *sc, struct vmbus_xact *xact,
     void *req, int reqlen, size_t *resplen0, uint32_t type)
 {
@@ -653,3 +653,54 @@
 
 	return (ret);
 }
+
+int
+hn_nvs_alloc_subchans(struct hn_softc *sc, int *nsubch0)
+{
+	struct vmbus_xact *xact;
+	struct hn_nvs_subch_req *req;
+	const struct hn_nvs_subch_resp *resp;
+	int error, nsubch_req;
+	uint32_t nsubch;
+	size_t resp_len;
+
+	nsubch_req = *nsubch0;
+	KASSERT(nsubch_req > 0, ("invalid # of sub-channels %d", nsubch_req));
+
+	xact = vmbus_xact_get(sc->hn_xact, sizeof(*req));
+	if (xact == NULL) {
+		if_printf(sc->hn_ifp, "no xact for nvs subch alloc\n");
+		return (ENXIO);
+	}
+	req = vmbus_xact_req_data(xact);
+	req->nvs_type = HN_NVS_TYPE_SUBCH_REQ;
+	req->nvs_op = HN_NVS_SUBCH_OP_ALLOC;
+	req->nvs_nsubch = nsubch_req;
+
+	resp_len = sizeof(*resp);
+	resp = hn_nvs_xact_execute(sc, xact, req, sizeof(*req), &resp_len,
+	    HN_NVS_TYPE_SUBCH_RESP);
+	if (resp == NULL) {
+		if_printf(sc->hn_ifp, "exec nvs subch alloc failed\n");
+		error = EIO;
+		goto done;
+	}
+	if (resp->nvs_status != HN_NVS_STATUS_OK) {
+		if_printf(sc->hn_ifp, "nvs subch alloc failed: %x\n",
+		    resp->nvs_status);
+		error = EIO;
+		goto done;
+	}
+
+	nsubch = resp->nvs_nsubch;
+	if (nsubch > nsubch_req) {
+		if_printf(sc->hn_ifp, "%u subchans are allocated, "
+		    "requested %d\n", nsubch, nsubch_req);
+		nsubch = nsubch_req;
+	}
+	*nsubch0 = nsubch;
+	error = 0;
+done:
+	vmbus_xact_put(xact);
+	return (error);
+}
Index: head/sys/dev/hyperv/netvsc/hv_rndis_filter.c
===================================================================
--- head/sys/dev/hyperv/netvsc/hv_rndis_filter.c
+++ head/sys/dev/hyperv/netvsc/hv_rndis_filter.c
@@ -1017,13 +1017,7 @@
 	int ret;
 	netvsc_device_info *dev_info = (netvsc_device_info *)additl_info;
 	device_t dev = sc->hn_dev;
-	struct hn_nvs_subch_req *req;
-	const struct hn_nvs_subch_resp *resp;
-	size_t resp_len;
-	struct vmbus_xact *xact = NULL;
-	uint32_t status, nsubch;
-	int nchan = *nchan0;
-	int rxr_cnt;
+	int nchan = *nchan0, rxr_cnt, nsubch;
 
 	ret = hn_nvs_attach(sc, mtu);
 	if (ret != 0)
@@ -1072,65 +1066,40 @@
 		*nchan0 = 1;
 		return (0);
 	}
-	if (nchan > rxr_cnt)
-		nchan = rxr_cnt;
 	if_printf(sc->hn_ifp, "RX rings offered %u, requested %d\n",
 	    rxr_cnt, nchan);
 
+	if (nchan > rxr_cnt)
+		nchan = rxr_cnt;
 	if (nchan == 1) {
 		device_printf(dev, "only 1 channel is supported, no vRSS\n");
-		goto out;
+		*nchan0 = 1;
+		return (0);
 	}
 	
 	/*
-	 * Ask NVS to allocate sub-channels.
+	 * Allocate sub-channels from NVS.
 	 */
-	xact = vmbus_xact_get(sc->hn_xact, sizeof(*req));
-	if (xact == NULL) {
-		if_printf(sc->hn_ifp, "no xact for nvs subch req\n");
-		ret = ENXIO;
-		goto out;
-	}
-	req = vmbus_xact_req_data(xact);
-	req->nvs_type = HN_NVS_TYPE_SUBCH_REQ;
-	req->nvs_op = HN_NVS_SUBCH_OP_ALLOC;
-	req->nvs_nsubch = nchan - 1;
-
-	resp_len = sizeof(*resp);
-	resp = hn_nvs_xact_execute(sc, xact, req, sizeof(*req), &resp_len,
-	    HN_NVS_TYPE_SUBCH_RESP);
-	if (resp == NULL) {
-		if_printf(sc->hn_ifp, "exec subch failed\n");
-		ret = EIO;
-		goto out;
-	}
-
-	status = resp->nvs_status;
-	nsubch = resp->nvs_nsubch;
-	vmbus_xact_put(xact);
-	xact = NULL;
-
-	if (status != HN_NVS_STATUS_OK) {
-		if_printf(sc->hn_ifp, "subch req failed: %x\n", status);
-		ret = EIO;
-		goto out;
-	}
-	if (nsubch > nchan - 1) {
-		if_printf(sc->hn_ifp, "%u subchans are allocated, requested %u\n",
-		    nsubch, nchan - 1);
-		nsubch = nchan - 1;
+	nsubch = nchan - 1;
+	ret = hn_nvs_alloc_subchans(sc, &nsubch);
+	if (ret || nsubch == 0) {
+		/* Failed to allocate sub-channels. */
+		*nchan0 = 1;
+		return (0);
 	}
 	nchan = nsubch + 1;
 
+	/*
+	 * Configure RSS key and indirect table after all sub-channels
+	 * are allocated.
+	 */
 	ret = hn_rndis_conf_rss(sc, nchan);
-	if (ret != 0)
-		*nchan0 = 1;
-	else
-		*nchan0 = nchan;
-out:
-	if (xact != NULL)
-		vmbus_xact_put(xact);
-	return (ret);
+	if (ret != 0) {
+		/* Failed to configure RSS key or indirect table. */
+		nchan = 1;
+	}
+	*nchan0 = nchan;
+	return (0);
 }
 
 /*
Index: head/sys/dev/hyperv/netvsc/if_hnvar.h
===================================================================
--- head/sys/dev/hyperv/netvsc/if_hnvar.h
+++ head/sys/dev/hyperv/netvsc/if_hnvar.h
@@ -114,9 +114,6 @@
 struct vmbus_xact;
 struct rndis_packet_msg;
 
-const void	*hn_nvs_xact_execute(struct hn_softc *sc,
-		    struct vmbus_xact *xact, void *req, int reqlen,
-		    size_t *resp_len, uint32_t type);
 void		hn_nvs_sent_xact(struct hn_send_ctx *sndc, struct hn_softc *sc,
 		    struct vmbus_channel *chan, const void *data, int dlen);
 uint32_t	hn_chim_alloc(struct hn_softc *sc);
@@ -125,6 +122,7 @@
 void		*hn_rndis_pktinfo_append(struct rndis_packet_msg *,
 		    size_t pktsize, size_t pi_dlen, uint32_t pi_type);
 
+int		hn_nvs_alloc_subchans(struct hn_softc *sc, int *nsubch);
 int		hn_rxpkt(struct hn_rx_ring *rxr, const void *data, int dlen,
 		    const struct hn_recvinfo *info);
 void		hn_chan_rollup(struct hn_rx_ring *rxr, struct hn_tx_ring *txr);