selftests/bpf: Add XDP load-balancer common definitions

Add the shared header for the XDP load-balancer benchmark.  This
defines the data structures used by both the BPF program and
userspace: flow_key, vip_definition, real_definition, and the
stats/control structures.

Also provides the encapsulation source-address helpers shared
between the BPF datapath (for encap) and userspace (for building
expected output packets used in validation).

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20260427232313.1582588-5-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/xdp_lb_bench_common.h b/tools/testing/selftests/bpf/xdp_lb_bench_common.h
new file mode 100644 (file)
index 0000000..aed20a9
--- /dev/null
+++ b/tools/testing/selftests/bpf/xdp_lb_bench_common.h
@@ -0,0 +1,112 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */
+
+#ifndef XDP_LB_BENCH_COMMON_H
+#define XDP_LB_BENCH_COMMON_H
+
+#define F_IPV6         (1 << 0)
+#define F_LRU_BYPASS   (1 << 1)
+
+#define CH_RING_SIZE   65537           /* per-VIP consistent hash ring slots */
+#define MAX_VIPS       16
+#define CH_RINGS_SIZE  (MAX_VIPS * CH_RING_SIZE)
+#define MAX_REALS      512
+#define DEFAULT_LRU_SIZE 100000                /* connection tracking cache size */
+#define ONE_SEC                1000000000U     /* 1 sec in nanosec */
+#define MAX_CONN_RATE  100000000       /* high enough to never trigger in bench */
+#define LRU_UDP_TIMEOUT        30000000000ULL  /* 30 sec in nanosec */
+#define PCKT_FRAGMENTED        0x3FFF
+#define KNUTH_HASH_MULT        2654435761U
+#define IPIP_V4_PREFIX 4268            /* 172.16/12 in network order */
+#define IPIP_V6_PREFIX1        1               /* 0100::/64 (RFC 6666 discard) */
+#define IPIP_V6_PREFIX2        0
+#define IPIP_V6_PREFIX3        0
+
+/* Stats indices (0..MAX_VIPS-1 are per-VIP packet/byte counters) */
+#define STATS_LRU      (MAX_VIPS + 0)  /* v1: total VIP packets, v2: LRU misses */
+#define STATS_XDP_TX   (MAX_VIPS + 1)
+#define STATS_XDP_PASS (MAX_VIPS + 2)
+#define STATS_XDP_DROP (MAX_VIPS + 3)
+#define STATS_NEW_CONN (MAX_VIPS + 4)  /* v1: conn count, v2: last reset ts */
+#define STATS_LRU_MISS (MAX_VIPS + 5)  /* v1: TCP LRU misses */
+#define STATS_SIZE     (MAX_VIPS + 6)
+
+#ifdef __BPF__
+#define lb_htons(x)    bpf_htons(x)
+#define LB_INLINE      static __always_inline
+#else
+#define lb_htons(x)    htons(x)
+#define LB_INLINE      static inline
+#endif
+
+LB_INLINE __be32 create_encap_ipv4_src(__u16 port, __be32 src)
+{
+       __u32 ip_suffix = lb_htons(port);
+
+       ip_suffix <<= 16;
+       ip_suffix ^= src;
+       return (0xFFFF0000 & ip_suffix) | IPIP_V4_PREFIX;
+}
+
+LB_INLINE void create_encap_ipv6_src(__u16 port, __be32 src, __be32 *saddr)
+{
+       saddr[0] = IPIP_V6_PREFIX1;
+       saddr[1] = IPIP_V6_PREFIX2;
+       saddr[2] = IPIP_V6_PREFIX3;
+       saddr[3] = src ^ port;
+}
+
+struct flow_key {
+       union {
+               __be32 src;
+               __be32 srcv6[4];
+       };
+       union {
+               __be32 dst;
+               __be32 dstv6[4];
+       };
+       union {
+               __u32 ports;
+               __u16 port16[2];
+       };
+       __u8 proto;
+       __u8 pad[3];
+};
+
+struct vip_definition {
+       union {
+               __be32 vip;
+               __be32 vipv6[4];
+       };
+       __u16 port;
+       __u8 proto;
+       __u8 pad;
+};
+
+struct vip_meta {
+       __u32 flags;
+       __u32 vip_num;
+};
+
+struct real_pos_lru {
+       __u32 pos;
+       __u64 atime;
+};
+
+struct real_definition {
+       __be32 dst;
+       __be32 dstv6[4];
+       __u8   flags;
+};
+
+struct lb_stats {
+       __u64 v1;
+       __u64 v2;
+};
+
+struct ctl_value {
+       __u8 mac[6];
+       __u8 pad[2];
+};
+
+#endif /* XDP_LB_BENCH_COMMON_H */