netdev - Re: [xdp-hints] [PATCH RFCv2 bpf-next 00/18] XDP-hints: XDP gaining access to HW offload hints via BTF

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Date:   Thu,  8 Sep 2022 11:30:43 +0200
From:   Alexander Lobakin <alexandr.lobakin@...el.com>
To:     Jesper Dangaard Brouer <brouer@...hat.com>
Cc:     Alexander Lobakin <alexandr.lobakin@...el.com>,
        bpf@...r.kernel.org, netdev@...r.kernel.org,
        xdp-hints@...-project.net, larysa.zaremba@...el.com,
        memxor@...il.com, Lorenzo Bianconi <lorenzo@...nel.org>,
        mtahhan@...hat.com,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Daniel Borkmann <borkmann@...earbox.net>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>,
        dave@...cker.co.uk, Magnus Karlsson <magnus.karlsson@...el.com>,
        bjorn@...nel.org
Subject: Re: [xdp-hints] [PATCH RFCv2 bpf-next 00/18] XDP-hints: XDP gaining access to HW offload hints via BTF

From: Jesper Dangaard Brouer <brouer@...hat.com>
Date: Wed, 07 Sep 2022 17:45:00 +0200

> This patchset expose the traditional hardware offload hints to XDP and
> rely on BTF to expose the layout to users.
> 
> Main idea is that the kernel and NIC drivers simply defines the struct
> layouts they choose to use for XDP-hints. These XDP-hints structs gets
> naturally and automatically described via BTF and implicitly exported to
> users. NIC drivers populate and records their own BTF ID as the last
> member in XDP metadata area (making it easily accessible by AF_XDP
> userspace at a known negative offset from packet data start).
> 
> Naming conventions for the structs (xdp_hints_*) is used such that
> userspace can find and decode the BTF layout and match against the
> provided BTF IDs. Thus, no new UAPI interfaces are needed for exporting
> what XDP-hints a driver supports.
> 
> The patch "i40e: Add xdp_hints_union" introduce the idea of creating a
> union named "xdp_hints_union" in every driver, which contains all
> xdp_hints_* struct this driver can support. This makes it easier/quicker
> to find and parse the relevant BTF types.  (Seeking input before fixing
> up all drivers in patchset).
> 
> 
> The main different from RFC-v1:
>  - Drop idea of BTF "origin" (vmlinux, module or local)
>  - Instead to use full 64-bit BTF ID that combine object+type ID
> 
> I've taken some of Alexandr/Larysa's libbpf patches and integrated
> those.

Not sure if it's okay to inform the authors about the fact only
after sending? Esp from the eeeh... "incompatible" implementation?
I realize it's open code, but this looks sorta depreciatingly.

> 
> Patchset exceeds netdev usually max 15 patches rule. My excuse is three
> NIC drivers (i40e, ixgbe and mvneta) gets XDP-hints support and which
> required some refactoring to remove the SKB dependencies.
> 
> 
> ---
> 
> Jesper Dangaard Brouer (10):
>       net: create xdp_hints_common and set functions
>       net: add net_device feature flag for XDP-hints
>       xdp: controlling XDP-hints from BPF-prog via helper
>       i40e: Refactor i40e_ptp_rx_hwtstamp
>       i40e: refactor i40e_rx_checksum with helper
>       bpf: export btf functions for modules
>       btf: Add helper for kernel modules to lookup full BTF ID
>       i40e: add XDP-hints handling
>       net: use XDP-hints in xdp_frame to SKB conversion
>       i40e: Add xdp_hints_union
> 
> Larysa Zaremba (3):
>       libbpf: factor out BTF loading from load_module_btfs()
>       libbpf: try to load vmlinux BTF from the kernel first
>       libbpf: patch module BTF obj+type ID into BPF insns
> 
> Lorenzo Bianconi (1):
>       mvneta: add XDP-hints support
> 
> Maryam Tahhan (4):
>       ixgbe: enable xdp-hints
>       ixgbe: add rx timestamp xdp hints support
>       xsk: AF_XDP xdp-hints support in desc options
>       ixgbe: AF_XDP xdp-hints processing in ixgbe_clean_rx_irq_zc
> 
> 
>  drivers/net/ethernet/intel/i40e/i40e.h        |   1 +
>  drivers/net/ethernet/intel/i40e/i40e_main.c   |  22 ++
>  drivers/net/ethernet/intel/i40e/i40e_ptp.c    |  36 ++-
>  drivers/net/ethernet/intel/i40e/i40e_txrx.c   | 252 ++++++++++++++---
>  drivers/net/ethernet/intel/ixgbe/ixgbe.h      |   5 +
>  drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 217 +++++++++++++--
>  drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c  |  82 ++++--
>  drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c  |   2 +
>  drivers/net/ethernet/marvell/mvneta.c         |  59 +++-
>  include/linux/btf.h                           |   3 +
>  include/linux/netdev_features.h               |   3 +-
>  include/net/xdp.h                             | 256 +++++++++++++++++-
>  include/uapi/linux/bpf.h                      |  35 +++
>  include/uapi/linux/if_xdp.h                   |   2 +-
>  kernel/bpf/btf.c                              |  36 ++-
>  net/core/filter.c                             |  52 ++++
>  net/core/xdp.c                                |  22 +-
>  net/ethtool/common.c                          |   1 +
>  net/xdp/xsk.c                                 |   2 +-
>  net/xdp/xsk_queue.h                           |   3 +-
>  tools/lib/bpf/bpf_core_read.h                 |   3 +-
>  tools/lib/bpf/btf.c                           | 142 +++++++++-
>  tools/lib/bpf/libbpf.c                        |  52 +---
>  tools/lib/bpf/libbpf_internal.h               |   7 +-
>  tools/lib/bpf/relo_core.c                     |   8 +-
>  tools/lib/bpf/relo_core.h                     |   1 +
>  26 files changed, 1127 insertions(+), 177 deletions(-)
> 
> --

Olek