This patchset introduces XDP support to the bonding driver. The motivation for this change is to enable use of bonding (and 802.3ad) in hairpinning L4 load-balancers such as [1] implemented with XDP and also to transparently support bond devices for projects that use XDP given most modern NICs have dual port adapters. An alternative to this approach would be to implement 802.3ad in user-space and implement the bonding load-balancing in the XDP program itself, but is rather a cumbersome endeavor in terms of slave device management (e.g. by watching netlink) and requires separate programs for native vs bond cases for the orchestrator. A native in-kernel implementation overcomes these issues and provides more flexibility. Below are benchmark results done on two machines with 100Gbit Intel E810 (ice) NIC and with 32-core 3970X on sending machine, and 16-core 3950X on receiving machine. 64 byte packets were sent with pktgen-dpdk at full rate. Two issues [2, 3] were identified with the ice driver, so the tests were performed with iommu=off and patch [2] applied. Additionally the bonding round robin algorithm was modified to use per-cpu tx counters as high CPU load (50% vs 10%) and high rate of cache misses were caused by the shared rr_tx_counter. Fix for this has been already merged into net-next. The statistics were collected using "sar -n dev -u 1 10". -----------------------| CPU |--| rxpck/s |--| txpck/s |---- without patch (1 dev): XDP_DROP: 3.15% 48.6Mpps XDP_TX: 3.12% 18.3Mpps 18.3Mpps XDP_DROP (RSS): 9.47% 116.5Mpps XDP_TX (RSS): 9.67% 25.3Mpps 24.2Mpps ----------------------- with patch, bond (1 dev): XDP_DROP: 3.14% 46.7Mpps XDP_TX: 3.15% 13.9Mpps 13.9Mpps XDP_DROP (RSS): 10.33% 117.2Mpps XDP_TX (RSS): 10.64% 25.1Mpps 24.0Mpps ----------------------- with patch, bond (2 devs): XDP_DROP: 6.27% 92.7Mpps XDP_TX: 6.26% 17.6Mpps 17.5Mpps XDP_DROP (RSS): 11.38% 117.2Mpps XDP_TX (RSS): 14.30% 28.7Mpps 27.4Mpps -------------------------------------------------------------- RSS: Receive Side Scaling, e.g. the packets were sent to a range of destination IPs. [1]: https://cilium.io/blog/2021/05/20/cilium-110#standalonelb [2]: https://lore.kernel.org/bpf/20210601113236.42651-1-maciej.fijalkowski@xxxxxxxxx/T/#t [3]: https://lore.kernel.org/bpf/CAHn8xckNXci+X_Eb2WMv4uVYjO2331UWB2JLtXr_58z0Av8+8A@xxxxxxxxxxxxxx/ Patch 1 prepares bond_xmit_hash for hashing xdp_buff's. Patch 2 adds hooks to implement redirection after bpf prog run. Patch 3 implements the hooks in the bonding driver. Patch 4 modifies devmap to properly handle EXCLUDE_INGRESS with a slave device. Patch 5 fixes an issue related to recent cleanup of rcu_read_lock in XDP context. Patch 6 fixes loading of xdp_tx.o by renaming section name. Patch 7 adds tests. v5->v6: - Address Andrii's comments about the tests. v4->v5: - As pointed by Andrii, use the generated BPF skeletons rather than libbpf directly. - Renamed section name in progs/xdp_tx.c as the BPF skeleton wouldn't load it otherwise due to unknown program type. - Daniel Borkmann noted that to retain backwards compatibility and allow some use cases we should allow attaching XDP programs to a slave device when the master does not have a program loaded. Modified the logic to allow this and added tests for the different combinations of attaching a program. v3->v4: - Add back the test suite, while removing the vmtest.sh modifications to kernel config new that CONFIG_BONDING=y is set. Discussed with Magnus Karlsson that it makes sense right now to not reuse the code from xdpceiver.c for testing XDP bonding. v2->v3: - Address Jay's comment to properly exclude upper devices with EXCLUDE_INGRESS when there are deeper nesting involved. Now all upper devices are excluded. - Refuse to enslave devices that already have XDP programs loaded and refuse to load XDP programs to slave devices. Earlier one could have a XDP program loaded and after enslaving and loading another program onto the bond device the xdp_state of the enslaved device would be pointing at an old program. - Adapt netdev_lower_get_next_private_rcu so it can be called in the XDP context. v1->v2: - Split up into smaller easier to review patches and address cosmetic review comments. - Drop the INDIRECT_CALL optimization as it showed little improvement in tests. - Drop the rr_tx_counter patch as that has already been merged into net-next. - Separate the test suite into another patch set. This will follow later once a patch set from Magnus Karlsson is merged and provides test utilities that can be reused for XDP bonding tests. v2 contains no major functional changes and was tested with the test suite included in v1. (https://lore.kernel.org/bpf/202106221509.kwNvAAZg-lkp@xxxxxxxxx/T/#m464146d47299125d5868a08affd6d6ce526dfad1) ---
