selftests/bpf: Add XDP load-balancer BPF program

Add the BPF datapath for the XDP load-balancer benchmark, a
simplified L4 load-balancer inspired by katran.

The pipeline: L3/L4 parse -> VIP lookup -> per-CPU LRU connection
table or consistent-hash fallback -> real server lookup -> per-VIP
and per-real stats -> IPIP/IP6IP6 encapsulation.  TCP SYN forces
the consistent-hash path (skipping LRU); TCP RST skips LRU insert
to avoid polluting the table.

process_packet() is marked __noinline so that the BENCH_BPF_LOOP
reset block (which strips encapsulation) operates on valid packet
pointers after bpf_xdp_adjust_head().

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20260427232313.1582588-6-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Puranjay Mohan 2026-04-27 16:23:02 -07:00 • committed by Alexei Starovoitov
commit 4b4f222910