ionic: support ethtool rxhash disable

We can disable rxhashing by setting rss_types to 0.  The user
can toggle this with "ethtool -K <ethX> rxhash off|on",
which calls into the .ndo_set_features callback with the
NETIF_F_RXHASH feature bit set or cleared.  This patch adds
a check for that bit and updates the FW if necessary.
Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/pensando/ionic/ionic_lif.c

@@ -1094,6 +1094,7 @@ static int ionic_set_nic_features(struct ionic_lif *lif,
 	u64 vlan_flags = IONIC_ETH_HW_VLAN_TX_TAG |
 			 IONIC_ETH_HW_VLAN_RX_STRIP |
 			 IONIC_ETH_HW_VLAN_RX_FILTER;
+	u64 old_hw_features;
 	int err;
 
 	ctx.cmd.lif_setattr.features = ionic_netdev_features_to_nic(features);
@@ -1101,9 +1102,13 @@ static int ionic_set_nic_features(struct ionic_lif *lif,
 	if (err)
 		return err;
 
+	old_hw_features = lif->hw_features;
 	lif->hw_features = le64_to_cpu(ctx.cmd.lif_setattr.features &
 				       ctx.comp.lif_setattr.features);
 
+	if ((old_hw_features ^ lif->hw_features) & IONIC_ETH_HW_RX_HASH)
+		ionic_lif_rss_config(lif, lif->rss_types, NULL, NULL);
+
 	if ((vlan_flags & features) &&
 	    !(vlan_flags & le64_to_cpu(ctx.comp.lif_setattr.features)))
 		dev_info_once(lif->ionic->dev, "NIC is not supporting vlan offload, likely in SmartNIC mode\n");
@@ -1357,13 +1362,15 @@ int ionic_lif_rss_config(struct ionic_lif *lif, const u16 types,
 		.cmd.lif_setattr = {
 			.opcode = IONIC_CMD_LIF_SETATTR,
 			.attr = IONIC_LIF_ATTR_RSS,
-			.rss.types = cpu_to_le16(types),
 			.rss.addr = cpu_to_le64(lif->rss_ind_tbl_pa),
 		},
 	};
 	unsigned int i, tbl_sz;
 
-	lif->rss_types = types;
+	if (lif->hw_features & IONIC_ETH_HW_RX_HASH) {
+		lif->rss_types = types;
+		ctx.cmd.lif_setattr.rss.types = cpu_to_le16(types);
+	}
 
 	if (key)
 		memcpy(lif->rss_hash_key, key, IONIC_RSS_HASH_KEY_SIZE);