[RFCv2 bpf-next 0/7] Add bpf_xdp_get_xfrm_state() kfunc

[Daniel Xu <dxu@dxuuu.xyz>]

This patchset adds two kfunc helpers, bpf_xdp_get_xfrm_state() and
bpf_xdp_xfrm_state_release() that wrap xfrm_state_lookup() and
xfrm_state_put(). The intent is to support software RSS (via XDP) for
the ongoing/upcoming ipsec pcpu work [0]. Recent experiments performed
on (hopefully) reproducible AWS testbeds indicate that single tunnel
pcpu ipsec can reach line rate on 100G ENA nics.

Note this patchset only tests/shows generic xfrm_state access. The
"secret sauce" (if you can really even call it that) involves accessing
a soon-to-be-upstreamed pcpu_num field in xfrm_state. Early example is
available here [1].

[0]: https://datatracker.ietf.org/doc/html/draft-ietf-ipsecme-multi-sa-performance-02
[1]: https://github.com/danobi/xdp-tools/blob/e89a1c617aba3b50d990f779357d6ce2863ecb27/xdp-bench/xdp_redirect_cpumap.bpf.c#L385-L406

Changes from RFCv1:
* Add Antony's commit tags
* Add KF_ACQUIRE and KF_RELEASE semantics

Daniel Xu (7):
  bpf: xfrm: Add bpf_xdp_get_xfrm_state() kfunc
  bpf: xfrm: Add bpf_xdp_xfrm_state_release() kfunc
  bpf: selftests: test_tunnel: Use ping -6 over ping6
  bpf: selftests: test_tunnel: Mount bpffs if necessary
  bpf: selftests: test_tunnel: Use vmlinux.h declarations
  bpf: selftests: test_tunnel: Disable CO-RE relocations
  bpf: xfrm: Add selftest for bpf_xdp_get_xfrm_state()

 include/net/xfrm.h                            |   9 ++
 net/xfrm/Makefile                             |   1 +
 net/xfrm/xfrm_policy.c                        |   2 +
 net/xfrm/xfrm_state_bpf.c                     | 121 ++++++++++++++++++
 .../selftests/bpf/progs/bpf_tracing_net.h     |   1 +
 .../selftests/bpf/progs/test_tunnel_kern.c    |  98 ++++++++------
 tools/testing/selftests/bpf/test_tunnel.sh    |  43 +++++--
 7 files changed, 221 insertions(+), 54 deletions(-)
 create mode 100644 net/xfrm/xfrm_state_bpf.c

-- 
2.42.0