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. The main idea for the new multi-buffer layout is to reuse the same structure used for non-linear SKB. This rely on the "skb_shared_info" struct at the end of the first buffer to link together subsequent buffers. Keeping the layout compatible with SKBs is also done to ease and speedup creating a SKB from an xdp_{buff,frame}. Converting xdp_frame to SKB and deliver it to the network stack is shown in patch 05/18 (e.g. cpumaps). A multi-buffer bit (mb) has been introduced in the flags field of 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 skb_shared_info structure at the end of the first buffer will be initialized only if mb is set. Moreover the flags field in xdp_{buff,frame} will be reused even for xdp rx csum offloading in future series. Typical use cases for this series are: - Jumbo-frames - Packet header split (please see Google’s use-case @ NetDevConf 0x14, [0]) - TSO/GRO The two following ebpf helpers (and related selftests) has been introduced: - bpf_xdp_adjust_data: Move xdp_md->data and xdp_md->data_end pointers in subsequent fragments according to the offset provided by the ebpf program. This helper can be used to read/write values in frame payload. - bpf_xdp_get_buff_len: Return 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 v11: - add missing static to bpf_xdp_get_buff_len_proto structure - fix bpf_xdp_adjust_data helper when offset is smaller than linear area length. Changes since v10: - move xdp->data to the requested payload offset instead of to the beginning of the fragment in bpf_xdp_adjust_data() Changes since v9: - introduce bpf_xdp_adjust_data helper and related selftest - add xdp_frags_size and xdp_frags_tsize fields in skb_shared_info - introduce xdp_update_skb_shared_info utility routine in ordere to not reset frags array in skb_shared_info converting from a xdp_buff/xdp_frame to a skb - simplify bpf_xdp_copy routine Changes since v8: - add proper dma unmapping if XDP_TX fails on mvneta for a xdp multi-buff - switch back to skb_shared_info implementation from previous xdp_shared_info one - avoid using a bietfield in xdp_buff/xdp_frame since it introduces performance regressions. Tested now on 10G NIC (ixgbe) to verify there are no performance penalties for regular codebase - add bpf_xdp_get_buff_len helper and remove frame_length field in xdp ctx - add data_len field in skb_shared_info struct - introduce XDP_FLAGS_FRAGS_PF_MEMALLOC flag 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 (3): bpf: add multi-buff support to the bpf_xdp_adjust_tail() API bpf: add multi-buffer support to xdp copy helpers bpf: update xdp_adjust_tail selftest to include multi-buffer Lorenzo Bianconi (15): net: skbuff: add size metadata to skb_shared_info for xdp xdp: introduce flags field in xdp_buff/xdp_frame net: mvneta: update mb bit before passing the xdp buffer to eBPF layer net: mvneta: simplify mvneta_swbm_add_rx_fragment management net: xdp: add xdp_update_skb_shared_info utility routine net: marvell: rely on xdp_update_skb_shared_info utility routine 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 bpf: introduce bpf_xdp_get_buff_len helper 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 net: xdp: introduce bpf_xdp_adjust_data helper bpf: add bpf_xdp_adjust_data selftest drivers/net/ethernet/marvell/mvneta.c | 204 ++++++++++------- include/linux/skbuff.h | 6 +- include/net/xdp.h | 95 +++++++- include/uapi/linux/bpf.h | 39 ++++ kernel/trace/bpf_trace.c | 3 + net/bpf/test_run.c | 117 ++++++++-- net/core/filter.c | 213 +++++++++++++++++- net/core/xdp.c | 76 ++++++- tools/include/uapi/linux/bpf.h | 39 ++++ .../bpf/prog_tests/xdp_adjust_data.c | 55 +++++ .../bpf/prog_tests/xdp_adjust_tail.c | 118 ++++++++++ .../selftests/bpf/prog_tests/xdp_bpf2bpf.c | 151 +++++++++---- .../bpf/progs/test_xdp_adjust_tail_grow.c | 10 +- .../bpf/progs/test_xdp_adjust_tail_shrink.c | 32 ++- .../selftests/bpf/progs/test_xdp_bpf2bpf.c | 2 +- .../bpf/progs/test_xdp_update_frags.c | 41 ++++ 16 files changed, 1036 insertions(+), 165 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_adjust_data.c create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_update_frags.c -- 2.31.1