[PATCH RFC v5 01/10] virtio_net: Add functions for hashing

[Akihiko Odaki <akihiko.odaki@daynix.com>]

They are useful to implement VIRTIO_NET_F_RSS and
VIRTIO_NET_F_HASH_REPORT.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
 include/linux/virtio_net.h | 188 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 188 insertions(+)

diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
index 276ca543ef44..6f192bb9ba1d 100644
--- a/include/linux/virtio_net.h
+++ b/include/linux/virtio_net.h
@@ -9,6 +9,194 @@
 #include <uapi/linux/tcp.h>
 #include <uapi/linux/virtio_net.h>
 
+struct virtio_net_hash {
+	u32 value;
+	u16 report;
+};
+
+struct virtio_net_toeplitz_state {
+	u32 hash;
+	const u32 *key;
+};
+
+#define VIRTIO_NET_SUPPORTED_HASH_TYPES (VIRTIO_NET_RSS_HASH_TYPE_IPv4 | \
+					 VIRTIO_NET_RSS_HASH_TYPE_TCPv4 | \
+					 VIRTIO_NET_RSS_HASH_TYPE_UDPv4 | \
+					 VIRTIO_NET_RSS_HASH_TYPE_IPv6 | \
+					 VIRTIO_NET_RSS_HASH_TYPE_TCPv6 | \
+					 VIRTIO_NET_RSS_HASH_TYPE_UDPv6)
+
+#define VIRTIO_NET_RSS_MAX_KEY_SIZE 40
+
+static inline void virtio_net_toeplitz_convert_key(u32 *input, size_t len)
+{
+	while (len >= sizeof(*input)) {
+		*input = be32_to_cpu((__force __be32)*input);
+		input++;
+		len -= sizeof(*input);
+	}
+}
+
+static inline void virtio_net_toeplitz_calc(struct virtio_net_toeplitz_state *state,
+					    const __be32 *input, size_t len)
+{
+	while (len >= sizeof(*input)) {
+		for (u32 map = be32_to_cpu(*input); map; map &= (map - 1)) {
+			u32 i = ffs(map);
+
+			state->hash ^= state->key[0] << (32 - i) |
+				       (u32)((u64)state->key[1] >> i);
+		}
+
+		state->key++;
+		input++;
+		len -= sizeof(*input);
+	}
+}
+
+static inline u8 virtio_net_hash_key_length(u32 types)
+{
+	size_t len = 0;
+
+	if (types & VIRTIO_NET_HASH_REPORT_IPv4)
+		len = max(len,
+			  sizeof(struct flow_dissector_key_ipv4_addrs));
+
+	if (types &
+	    (VIRTIO_NET_HASH_REPORT_TCPv4 | VIRTIO_NET_HASH_REPORT_UDPv4))
+		len = max(len,
+			  sizeof(struct flow_dissector_key_ipv4_addrs) +
+			  sizeof(struct flow_dissector_key_ports));
+
+	if (types & VIRTIO_NET_HASH_REPORT_IPv6)
+		len = max(len,
+			  sizeof(struct flow_dissector_key_ipv6_addrs));
+
+	if (types &
+	    (VIRTIO_NET_HASH_REPORT_TCPv6 | VIRTIO_NET_HASH_REPORT_UDPv6))
+		len = max(len,
+			  sizeof(struct flow_dissector_key_ipv6_addrs) +
+			  sizeof(struct flow_dissector_key_ports));
+
+	return len + 4;
+}
+
+static inline u32 virtio_net_hash_report(u32 types,
+					 const struct flow_keys_basic *keys)
+{
+	switch (keys->basic.n_proto) {
+	case cpu_to_be16(ETH_P_IP):
+		if (!(keys->control.flags & FLOW_DIS_IS_FRAGMENT)) {
+			if (keys->basic.ip_proto == IPPROTO_TCP &&
+			    (types & VIRTIO_NET_RSS_HASH_TYPE_TCPv4))
+				return VIRTIO_NET_HASH_REPORT_TCPv4;
+
+			if (keys->basic.ip_proto == IPPROTO_UDP &&
+			    (types & VIRTIO_NET_RSS_HASH_TYPE_UDPv4))
+				return VIRTIO_NET_HASH_REPORT_UDPv4;
+		}
+
+		if (types & VIRTIO_NET_RSS_HASH_TYPE_IPv4)
+			return VIRTIO_NET_HASH_REPORT_IPv4;
+
+		return VIRTIO_NET_HASH_REPORT_NONE;
+
+	case cpu_to_be16(ETH_P_IPV6):
+		if (!(keys->control.flags & FLOW_DIS_IS_FRAGMENT)) {
+			if (keys->basic.ip_proto == IPPROTO_TCP &&
+			    (types & VIRTIO_NET_RSS_HASH_TYPE_TCPv6))
+				return VIRTIO_NET_HASH_REPORT_TCPv6;
+
+			if (keys->basic.ip_proto == IPPROTO_UDP &&
+			    (types & VIRTIO_NET_RSS_HASH_TYPE_UDPv6))
+				return VIRTIO_NET_HASH_REPORT_UDPv6;
+		}
+
+		if (types & VIRTIO_NET_RSS_HASH_TYPE_IPv6)
+			return VIRTIO_NET_HASH_REPORT_IPv6;
+
+		return VIRTIO_NET_HASH_REPORT_NONE;
+
+	default:
+		return VIRTIO_NET_HASH_REPORT_NONE;
+	}
+}
+
+static inline void virtio_net_hash_rss(const struct sk_buff *skb,
+				       u32 types, const u32 *key,
+				       struct virtio_net_hash *hash)
+{
+	struct virtio_net_toeplitz_state toeplitz_state = { .key = key };
+	struct flow_keys flow;
+	struct flow_keys_basic flow_basic;
+	u16 report;
+
+	if (!skb_flow_dissect_flow_keys(skb, &flow, 0)) {
+		hash->report = VIRTIO_NET_HASH_REPORT_NONE;
+		return;
+	}
+
+	flow_basic = (struct flow_keys_basic) {
+		.control = flow.control,
+		.basic = flow.basic
+	};
+
+	report = virtio_net_hash_report(types, &flow_basic);
+
+	switch (report) {
+	case VIRTIO_NET_HASH_REPORT_IPv4:
+		virtio_net_toeplitz_calc(&toeplitz_state,
+					 (__be32 *)&flow.addrs.v4addrs,
+					 sizeof(flow.addrs.v4addrs));
+		break;
+
+	case VIRTIO_NET_HASH_REPORT_TCPv4:
+		virtio_net_toeplitz_calc(&toeplitz_state,
+					 (__be32 *)&flow.addrs.v4addrs,
+					 sizeof(flow.addrs.v4addrs));
+		virtio_net_toeplitz_calc(&toeplitz_state, &flow.ports.ports,
+					 sizeof(flow.ports.ports));
+		break;
+
+	case VIRTIO_NET_HASH_REPORT_UDPv4:
+		virtio_net_toeplitz_calc(&toeplitz_state,
+					 (__be32 *)&flow.addrs.v4addrs,
+					 sizeof(flow.addrs.v4addrs));
+		virtio_net_toeplitz_calc(&toeplitz_state, &flow.ports.ports,
+					 sizeof(flow.ports.ports));
+		break;
+
+	case VIRTIO_NET_HASH_REPORT_IPv6:
+		virtio_net_toeplitz_calc(&toeplitz_state,
+					 (__be32 *)&flow.addrs.v6addrs,
+					 sizeof(flow.addrs.v6addrs));
+		break;
+
+	case VIRTIO_NET_HASH_REPORT_TCPv6:
+		virtio_net_toeplitz_calc(&toeplitz_state,
+					 (__be32 *)&flow.addrs.v6addrs,
+					 sizeof(flow.addrs.v6addrs));
+		virtio_net_toeplitz_calc(&toeplitz_state, &flow.ports.ports,
+					 sizeof(flow.ports.ports));
+		break;
+
+	case VIRTIO_NET_HASH_REPORT_UDPv6:
+		virtio_net_toeplitz_calc(&toeplitz_state,
+					 (__be32 *)&flow.addrs.v6addrs,
+					 sizeof(flow.addrs.v6addrs));
+		virtio_net_toeplitz_calc(&toeplitz_state, &flow.ports.ports,
+					 sizeof(flow.ports.ports));
+		break;
+
+	default:
+		hash->report = VIRTIO_NET_HASH_REPORT_NONE;
+		return;
+	}
+
+	hash->value = toeplitz_state.hash;
+	hash->report = report;
+}
+
 static inline bool virtio_net_hdr_match_proto(__be16 protocol, __u8 gso_type)
 {
 	switch (gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {

-- 
2.46.2