drivers/net/virtio_net: Added RSS hash report control.

Now it's possible to control supported hashflows.
Added hashflow set/get callbacks.
Also, disabling RXH_IP_SRC/DST for TCP would disable then for UDP.
TCP and UDP supports only:
ethtool -U eth0 rx-flow-hash tcp4 sd
    RXH_IP_SRC + RXH_IP_DST
ethtool -U eth0 rx-flow-hash tcp4 sdfn
    RXH_IP_SRC + RXH_IP_DST + RXH_L4_B_0_1 + RXH_L4_B_2_3
Disabling happens because VirtioNET hashtype for IP doesn't check L4 proto,
it works for all IP packets(TCP, UDP, ICMP, etc.).
For TCP and UDP, it's possible to set IP+PORT hashes.
But disabling IP hashes will disable them for TCP and UDP simultaneously.
It's possible to set IP+PORT for TCP/UDP and disable/enable IP
for everything else(UDP, ICMP, etc.).
Signed-off-by: Andrew Melnychenko <andrew@daynix.com>
Link: https://lore.kernel.org/r/20220328175336.10802-5-andrew@daynix.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/net/virtio_net.c

@@ -231,6 +231,7 @@ struct virtnet_info {
 	u8 rss_key_size;
 	u16 rss_indir_table_size;
 	u32 rss_hash_types_supported;
+	u32 rss_hash_types_saved;
 
 	/* Has control virtqueue */
 	bool has_cvq;
@@ -2278,6 +2279,7 @@ static void virtnet_init_default_rss(struct virtnet_info *vi)
 	int i = 0;
 
 	vi->ctrl->rss.hash_types = vi->rss_hash_types_supported;
+	vi->rss_hash_types_saved = vi->rss_hash_types_supported;
 	vi->ctrl->rss.indirection_table_mask = vi->rss_indir_table_size
 						? vi->rss_indir_table_size - 1 : 0;
 	vi->ctrl->rss.unclassified_queue = 0;
@@ -2293,6 +2295,121 @@ static void virtnet_init_default_rss(struct virtnet_info *vi)
 	netdev_rss_key_fill(vi->ctrl->rss.key, vi->rss_key_size);
 }
 
+static void virtnet_get_hashflow(const struct virtnet_info *vi, struct ethtool_rxnfc *info)
+{
+	info->data = 0;
+	switch (info->flow_type) {
+	case TCP_V4_FLOW:
+		if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_TCPv4) {
+			info->data = RXH_IP_SRC | RXH_IP_DST |
+						 RXH_L4_B_0_1 | RXH_L4_B_2_3;
+		} else if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_IPv4) {
+			info->data = RXH_IP_SRC | RXH_IP_DST;
+		}
+		break;
+	case TCP_V6_FLOW:
+		if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_TCPv6) {
+			info->data = RXH_IP_SRC | RXH_IP_DST |
+						 RXH_L4_B_0_1 | RXH_L4_B_2_3;
+		} else if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_IPv6) {
+			info->data = RXH_IP_SRC | RXH_IP_DST;
+		}
+		break;
+	case UDP_V4_FLOW:
+		if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_UDPv4) {
+			info->data = RXH_IP_SRC | RXH_IP_DST |
+						 RXH_L4_B_0_1 | RXH_L4_B_2_3;
+		} else if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_IPv4) {
+			info->data = RXH_IP_SRC | RXH_IP_DST;
+		}
+		break;
+	case UDP_V6_FLOW:
+		if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_UDPv6) {
+			info->data = RXH_IP_SRC | RXH_IP_DST |
+						 RXH_L4_B_0_1 | RXH_L4_B_2_3;
+		} else if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_IPv6) {
+			info->data = RXH_IP_SRC | RXH_IP_DST;
+		}
+		break;
+	case IPV4_FLOW:
+		if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_IPv4)
+			info->data = RXH_IP_SRC | RXH_IP_DST;
+
+		break;
+	case IPV6_FLOW:
+		if (vi->rss_hash_types_saved & VIRTIO_NET_RSS_HASH_TYPE_IPv6)
+			info->data = RXH_IP_SRC | RXH_IP_DST;
+
+		break;
+	default:
+		info->data = 0;
+		break;
+	}
+}
+
+static bool virtnet_set_hashflow(struct virtnet_info *vi, struct ethtool_rxnfc *info)
+{
+	u32 new_hashtypes = vi->rss_hash_types_saved;
+	bool is_disable = info->data & RXH_DISCARD;
+	bool is_l4 = info->data == (RXH_IP_SRC | RXH_IP_DST | RXH_L4_B_0_1 | RXH_L4_B_2_3);
+
+	/* supports only 'sd', 'sdfn' and 'r' */
+	if (!((info->data == (RXH_IP_SRC | RXH_IP_DST)) | is_l4 | is_disable))
+		return false;
+
+	switch (info->flow_type) {
+	case TCP_V4_FLOW:
+		new_hashtypes &= ~(VIRTIO_NET_RSS_HASH_TYPE_IPv4 | VIRTIO_NET_RSS_HASH_TYPE_TCPv4);
+		if (!is_disable)
+			new_hashtypes |= VIRTIO_NET_RSS_HASH_TYPE_IPv4
+				| (is_l4 ? VIRTIO_NET_RSS_HASH_TYPE_TCPv4 : 0);
+		break;
+	case UDP_V4_FLOW:
+		new_hashtypes &= ~(VIRTIO_NET_RSS_HASH_TYPE_IPv4 | VIRTIO_NET_RSS_HASH_TYPE_UDPv4);
+		if (!is_disable)
+			new_hashtypes |= VIRTIO_NET_RSS_HASH_TYPE_IPv4
+				| (is_l4 ? VIRTIO_NET_RSS_HASH_TYPE_UDPv4 : 0);
+		break;
+	case IPV4_FLOW:
+		new_hashtypes &= ~VIRTIO_NET_RSS_HASH_TYPE_IPv4;
+		if (!is_disable)
+			new_hashtypes = VIRTIO_NET_RSS_HASH_TYPE_IPv4;
+		break;
+	case TCP_V6_FLOW:
+		new_hashtypes &= ~(VIRTIO_NET_RSS_HASH_TYPE_IPv6 | VIRTIO_NET_RSS_HASH_TYPE_TCPv6);
+		if (!is_disable)
+			new_hashtypes |= VIRTIO_NET_RSS_HASH_TYPE_IPv6
+				| (is_l4 ? VIRTIO_NET_RSS_HASH_TYPE_TCPv6 : 0);
+		break;
+	case UDP_V6_FLOW:
+		new_hashtypes &= ~(VIRTIO_NET_RSS_HASH_TYPE_IPv6 | VIRTIO_NET_RSS_HASH_TYPE_UDPv6);
+		if (!is_disable)
+			new_hashtypes |= VIRTIO_NET_RSS_HASH_TYPE_IPv6
+				| (is_l4 ? VIRTIO_NET_RSS_HASH_TYPE_UDPv6 : 0);
+		break;
+	case IPV6_FLOW:
+		new_hashtypes &= ~VIRTIO_NET_RSS_HASH_TYPE_IPv6;
+		if (!is_disable)
+			new_hashtypes = VIRTIO_NET_RSS_HASH_TYPE_IPv6;
+		break;
+	default:
+		/* unsupported flow */
+		return false;
+	}
+
+	/* if unsupported hashtype was set */
+	if (new_hashtypes != (new_hashtypes & vi->rss_hash_types_supported))
+		return false;
+
+	if (new_hashtypes != vi->rss_hash_types_saved) {
+		vi->rss_hash_types_saved = new_hashtypes;
+		vi->ctrl->rss.hash_types = vi->rss_hash_types_saved;
+		if (vi->dev->features & NETIF_F_RXHASH)
+			return virtnet_commit_rss_command(vi);
+	}
+
+	return true;
+}
 
 static void virtnet_get_drvinfo(struct net_device *dev,
 				struct ethtool_drvinfo *info)
@@ -2578,6 +2695,27 @@ static int virtnet_get_rxnfc(struct net_device *dev, struct ethtool_rxnfc *info,
 	switch (info->cmd) {
 	case ETHTOOL_GRXRINGS:
 		info->data = vi->curr_queue_pairs;
+		break;
+	case ETHTOOL_GRXFH:
+		virtnet_get_hashflow(vi, info);
+		break;
+	default:
+		rc = -EOPNOTSUPP;
+	}
+
+	return rc;
+}
+
+static int virtnet_set_rxnfc(struct net_device *dev, struct ethtool_rxnfc *info)
+{
+	struct virtnet_info *vi = netdev_priv(dev);
+	int rc = 0;
+
+	switch (info->cmd) {
+	case ETHTOOL_SRXFH:
+		if (!virtnet_set_hashflow(vi, info))
+			rc = -EINVAL;
+
 		break;
 	default:
 		rc = -EOPNOTSUPP;
@@ -2606,6 +2744,7 @@ static const struct ethtool_ops virtnet_ethtool_ops = {
 	.get_rxfh = virtnet_get_rxfh,
 	.set_rxfh = virtnet_set_rxfh,
 	.get_rxnfc = virtnet_get_rxnfc,
+	.set_rxnfc = virtnet_set_rxnfc,
 };
 
 static void virtnet_freeze_down(struct virtio_device *vdev)
@@ -2860,7 +2999,7 @@ static int virtnet_set_features(struct net_device *dev,
 
 	if ((dev->features ^ features) & NETIF_F_RXHASH) {
 		if (features & NETIF_F_RXHASH)
-			vi->ctrl->rss.hash_types = vi->rss_hash_types_supported;
+			vi->ctrl->rss.hash_types = vi->rss_hash_types_saved;
 		else
 			vi->ctrl->rss.hash_types = VIRTIO_NET_HASH_REPORT_NONE;