They are useful to implement VIRTIO_NET_F_RSS and
VIRTIO_NET_F_HASH_REPORT.

Signed-off-by: Akihiko Odaki <redacted>
Tested-by: Lei Yang <redacted>
---
 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 02a9f4dc594d..426f33b4b824 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 + sizeof(u32);
+}
+
+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;