Hyper-V: hn: add switch to turn on and off RSC

Currently RSC offloading is enabled by default.
With this new change rsc will be disabled by default.
By using sysctl we can enable and disable it.

Reviewed by:	whu
Signed-off-by:	Souradeep Chakrabarti <schakrabarti@microsoft.com>
Fixes:		a491581 Enable vSwitch RSC support in hn netvsc driver
MFC after:	1 week
Sponsored by:	Microsoft
Differential Revision:	https://reviews.freebsd.org/D34507

sys/dev/hyperv/netvsc/hn_rndis.c

@@ -579,6 +579,12 @@ hn_rndis_set(struct hn_softc *sc, uint32_t oid, const void *data, size_t dlen)
 	return (error);
 }
 
+int
+hn_rndis_reconf_offload(struct hn_softc *sc, int mtu)
+{
+	return(hn_rndis_conf_offload(sc, mtu));
+}
+
 static int
 hn_rndis_conf_offload(struct hn_softc *sc, int mtu)
 {
@@ -725,7 +731,8 @@ hn_rndis_conf_offload(struct hn_softc *sc, int mtu)
 
 	/* RSC offload */
 	if (hwcaps.ndis_hdr.ndis_rev >= NDIS_OFFLOAD_PARAMS_REV_3) {
-		if (hwcaps.ndis_rsc.ndis_ip4 && hwcaps.ndis_rsc.ndis_ip6) {
+		if (hwcaps.ndis_rsc.ndis_ip4 && hwcaps.ndis_rsc.ndis_ip6 &&
+		    sc->hn_rsc_ctrl) {
 			params.ndis_rsc_ip4 = NDIS_OFFLOAD_RSC_ON;
 			params.ndis_rsc_ip6 = NDIS_OFFLOAD_RSC_ON;
 		} else {

sys/dev/hyperv/netvsc/hn_rndis.h

@@ -46,5 +46,6 @@ int		hn_rndis_get_mtu(struct hn_softc *sc, uint32_t *mtu);
 int		hn_rndis_set_rxfilter(struct hn_softc *sc, uint32_t filter);
 void		hn_rndis_rx_ctrl(struct hn_softc *sc, const void *data,
 		    int dlen);
+int		hn_rndis_reconf_offload(struct hn_softc *sc, int mtu);
 
 #endif  /* !_HN_RNDIS_H_ */

sys/dev/hyperv/netvsc/if_hn.c

@@ -454,6 +454,8 @@ static void			hn_start_txeof(struct hn_tx_ring *);
 static void			hn_start_txeof_taskfunc(void *, int);
 #endif
 
+static int			hn_rsc_sysctl(SYSCTL_HANDLER_ARGS);
+
 SYSCTL_NODE(_hw, OID_AUTO, hn, CTLFLAG_RD | CTLFLAG_MPSAFE, NULL,
     "Hyper-V network interface");
 
@@ -2370,6 +2372,10 @@ hn_attach(device_t dev)
 		    "Accurate BPF for transparent VF");
 	}
 
+	SYSCTL_ADD_PROC(ctx, child, OID_AUTO, "rsc_switch",
+	    CTLTYPE_UINT | CTLFLAG_RW, sc, 0, hn_rsc_sysctl, "A",
+	    "switch to rsc");
+
 	/*
 	 * Setup the ifmedia, which has been initialized earlier.
 	 */
@@ -4567,6 +4573,30 @@ hn_rxfilter_sysctl(SYSCTL_HANDLER_ARGS)
 	return sysctl_handle_string(oidp, filter_str, sizeof(filter_str), req);
 }
 
+static int
+hn_rsc_sysctl(SYSCTL_HANDLER_ARGS)
+{
+	struct hn_softc *sc = arg1;
+	uint32_t mtu;
+	int error;
+	HN_LOCK(sc);
+	error = hn_rndis_get_mtu(sc, &mtu);
+	if (error) {
+		if_printf(sc->hn_ifp, "failed to get mtu\n");
+		goto back;
+	}
+	error = SYSCTL_OUT(req, &(sc->hn_rsc_ctrl), sizeof(sc->hn_rsc_ctrl));
+	if (error || req->newptr == NULL)
+		goto back;
+
+	error = SYSCTL_IN(req, &(sc->hn_rsc_ctrl), sizeof(sc->hn_rsc_ctrl));
+	if (error)
+		goto back;
+	error = hn_rndis_reconf_offload(sc, mtu);
+back:
+	HN_UNLOCK(sc);
+	return (error);
+}
 #ifndef RSS
 
 static int

sys/dev/hyperv/netvsc/if_hnvar.h

@@ -282,6 +282,11 @@ struct hn_softc {
 	u_int			hn_saved_tsomax;
 	u_int			hn_saved_tsosegcnt;
 	u_int			hn_saved_tsosegsz;
+
+	/*
+	 * RSC switch, default off
+	 */
+	u_int			hn_rsc_ctrl;
 };
 
 #define HN_FLAG_RXBUF_CONNECTED		0x0001