This series introduce XDP multi-buffer support. The mvneta driver is the first to support these new "non-linear" xdp_{buff,frame}. Reviewers please focus on how these new types of xdp_{buff,frame} packets traverse the different layers and the layout design. It is on purpose that BPF-helpers are kept simple, as we don't want to expose the internal layout to allow later changes. For now, to keep the design simple and to maintain performance, the XDP BPF-prog (still) only have access to the first-buffer. It is left for later (another patchset) to add payload access across multiple buffers. This patchset should still allow for these future extensions. The goal is to lift the XDP MTU restriction that comes with XDP, but maintain same performance as before. The main idea for the new multi-buffer layout is to reuse the same layout used for non-linear SKB. We introduced a "xdp_shared_info" data structure at the end of the first buffer to link together subsequent buffers. xdp_shared_info will alias skb_shared_info allowing to keep most of the frags in the same cache-line (while with skb_shared_info only the first fragment will be placed in the first "shared_info" cache-line). Moreover we introduced some xdp_shared_info helpers aligned to skb_frag* ones. Converting xdp_frame to SKB and deliver it to the network stack is shown in patch 07/14. Building the SKB, the xdp_shared_info structure will be converted in a skb_shared_info one. A multi-buffer bit (mb) has been introduced in xdp_{buff,frame} structure to notify the bpf/network layer if this is a xdp multi-buffer frame (mb = 1) or not (mb = 0). The mb bit will be set by a xdp multi-buffer capable driver only for non-linear frames maintaining the capability to receive linear frames without any extra cost since the xdp_shared_info structure at the end of the first buffer will be initialized only if mb is set. Typical use cases for this series are: - Jumbo-frames - Packet header split (please see Google’s use-case @ NetDevConf 0x14, [0]) - TSO A new frame_length field has been introduce in XDP ctx in order to notify the eBPF layer about the total frame size (linear + paged parts). bpf_xdp_adjust_tail and bpf_xdp_copy helpers have been modified to take into account xdp multi-buff frames. More info about the main idea behind this approach can be found here [1][2]. Changes since v7: - rebase on top of bpf-next - fix sparse warnings - improve comments for frame_length in include/net/xdp.h Changes since v6: - the main difference respect to previous versions is the new approach proposed by Eelco to pass full length of the packet to eBPF layer in XDP context - reintroduce multi-buff support to eBPF kself-tests - reintroduce multi-buff support to bpf_xdp_adjust_tail helper - introduce multi-buffer support to bpf_xdp_copy helper - rebase on top of bpf-next Changes since v5: - rebase on top of bpf-next - initialize mb bit in xdp_init_buff() and drop per-driver initialization - drop xdp->mb initialization in xdp_convert_zc_to_xdp_frame() - postpone introduction of frame_length field in XDP ctx to another series - minor changes Changes since v4: - rebase ontop of bpf-next - introduce xdp_shared_info to build xdp multi-buff instead of using the skb_shared_info struct - introduce frame_length in xdp ctx - drop previous bpf helpers - fix bpf_xdp_adjust_tail for xdp multi-buff - introduce xdp multi-buff self-tests for bpf_xdp_adjust_tail - fix xdp_return_frame_bulk for xdp multi-buff Changes since v3: - rebase ontop of bpf-next - add patch 10/13 to copy back paged data from a xdp multi-buff frame to userspace buffer for xdp multi-buff selftests Changes since v2: - add throughput measurements - drop bpf_xdp_adjust_mb_header bpf helper - introduce selftest for xdp multibuffer - addressed comments on bpf_xdp_get_frags_count - introduce xdp multi-buff support to cpumaps Changes since v1: - Fix use-after-free in xdp_return_{buff/frame} - Introduce bpf helpers - Introduce xdp_mb sample program - access skb_shared_info->nr_frags only on the last fragment Changes since RFC: - squash multi-buffer bit initialization in a single patch - add mvneta non-linear XDP buff support for tx side [0] https://netdevconf.info/0x14/session.html?talk-the-path-to-tcp-4k-mtu-and-rx-zerocopy [1] https://github.com/xdp-project/xdp-project/blob/master/areas/core/xdp-multi-buffer01-design.org [2] https://netdevconf.info/0x14/session.html?tutorial-add-XDP-support-to-a-NIC-driver (XDPmulti-buffers section) Eelco Chaudron (4): bpf: add multi-buff support to the bpf_xdp_adjust_tail() API bpd: add multi-buffer support to xdp copy helpers bpf: add new frame_length field to the XDP ctx bpf: update xdp_adjust_tail selftest to include multi-buffer Lorenzo Bianconi (10): xdp: introduce mb in xdp_buff/xdp_frame xdp: add xdp_shared_info data structure net: mvneta: update mb bit before passing the xdp buffer to eBPF layer xdp: add multi-buff support to xdp_return_{buff/frame} net: mvneta: add multi buffer support to XDP_TX net: mvneta: enable jumbo frames for XDP net: xdp: add multi-buff support to xdp_build_skb_from_fram bpf: move user_size out of bpf_test_init bpf: introduce multibuff support to bpf_prog_test_run_xdp() bpf: test_run: add xdp_shared_info pointer in bpf_test_finish signature drivers/net/ethernet/marvell/mvneta.c | 182 ++++++++++-------- include/linux/filter.h | 7 + include/net/xdp.h | 105 +++++++++- include/uapi/linux/bpf.h | 1 + net/bpf/test_run.c | 109 +++++++++-- net/core/filter.c | 134 ++++++++++++- net/core/xdp.c | 103 +++++++++- tools/include/uapi/linux/bpf.h | 1 + .../bpf/prog_tests/xdp_adjust_tail.c | 105 ++++++++++ .../selftests/bpf/prog_tests/xdp_bpf2bpf.c | 127 ++++++++---- .../bpf/progs/test_xdp_adjust_tail_grow.c | 17 +- .../bpf/progs/test_xdp_adjust_tail_shrink.c | 32 ++- .../selftests/bpf/progs/test_xdp_bpf2bpf.c | 3 +- 13 files changed, 767 insertions(+), 159 deletions(-) -- 2.30.2