Netdev Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Lorenzo Bianconi <lorenzo@kernel.org>
To: bpf@vger.kernel.org, netdev@vger.kernel.org
Cc: lorenzo.bianconi@redhat.com, davem@davemloft.net,
	kuba@kernel.org, ast@kernel.org, daniel@iogearbox.net,
	shayagr@amazon.com, john.fastabend@gmail.com, dsahern@kernel.org,
	brouer@redhat.com, echaudro@redhat.com, jasowang@redhat.com,
	alexander.duyck@gmail.com, saeed@kernel.org,
	maciej.fijalkowski@intel.com, magnus.karlsson@intel.com,
	tirthendu.sarkar@intel.com, toke@redhat.com
Subject: [PATCH v10 bpf-next 00/18] mvneta: introduce XDP multi-buffer support
Date: Wed, 28 Jul 2021 11:38:05 +0200	[thread overview]
Message-ID: <cover.1627463617.git.lorenzo@kernel.org> (raw)
Message-ID: <20210728093805.9fW8jECsJ2Wc1Ws1mCHh3FBQa6FISaej4uZMcY6_cm0@z> (raw)

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset=y, Size: 7360 bytes --]

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
layout 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

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 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         | 213 ++++++++++--------
 include/linux/skbuff.h                        |   6 +-
 include/net/xdp.h                             |  95 +++++++-
 include/uapi/linux/bpf.h                      |  38 ++++
 kernel/trace/bpf_trace.c                      |   3 +
 net/bpf/test_run.c                            | 117 ++++++++--
 net/core/filter.c                             | 210 ++++++++++++++++-
 net/core/xdp.c                                |  76 ++++++-
 tools/include/uapi/linux/bpf.h                |  38 ++++
 .../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         |  49 ++++
 16 files changed, 1044 insertions(+), 169 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


             reply	other threads:[~2021-07-28  9:38 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-28  9:33 Lorenzo Bianconi [this message]
2021-07-28  9:38 ` Lorenzo Bianconi
2021-07-28  9:38 ` [PATCH v10 bpf-next 01/18] net: skbuff: add size metadata to skb_shared_info for xdp Lorenzo Bianconi
2021-07-28  9:38 ` [PATCH v10 bpf-next 02/18] xdp: introduce flags field in xdp_buff/xdp_frame Lorenzo Bianconi
2021-07-28  9:38 ` [PATCH v10 bpf-next 03/18] net: mvneta: update mb bit before passing the xdp buffer to eBPF layer Lorenzo Bianconi
2021-07-28  9:38 ` [PATCH v10 bpf-next 04/18] net: mvneta: simplify mvneta_swbm_add_rx_fragment management Lorenzo Bianconi
2021-07-28  9:38 ` [PATCH v10 bpf-next 05/18] net: xdp: add xdp_update_skb_shared_info utility routine Lorenzo Bianconi
2021-07-28  9:38 ` [PATCH v10 bpf-next 06/18] net: marvell: rely on " Lorenzo Bianconi
2021-07-28  9:38 ` [PATCH v10 bpf-next 07/18] xdp: add multi-buff support to xdp_return_{buff/frame} Lorenzo Bianconi
2021-07-28  9:38 ` [PATCH v10 bpf-next 08/18] net: mvneta: add multi buffer support to XDP_TX Lorenzo Bianconi
2021-07-28  9:38 ` [PATCH v10 bpf-next 09/18] net: mvneta: enable jumbo frames for XDP Lorenzo Bianconi
2021-07-28  9:38 ` [PATCH v10 bpf-next 10/18] bpf: add multi-buff support to the bpf_xdp_adjust_tail() API Lorenzo Bianconi
2021-07-28  9:38 ` [PATCH v10 bpf-next 11/18] bpf: introduce bpf_xdp_get_buff_len helper Lorenzo Bianconi
2021-07-28  9:38 ` [PATCH v10 bpf-next 12/18] bpf: add multi-buffer support to xdp copy helpers Lorenzo Bianconi
2021-07-28  9:38 ` [PATCH v10 bpf-next 13/18] bpf: move user_size out of bpf_test_init Lorenzo Bianconi
2021-07-28  9:38 ` [PATCH v10 bpf-next 14/18] bpf: introduce multibuff support to bpf_prog_test_run_xdp() Lorenzo Bianconi
2021-07-28  9:38 ` [PATCH v10 bpf-next 15/18] bpf: test_run: add xdp_shared_info pointer in bpf_test_finish signature Lorenzo Bianconi
2021-07-28  9:38 ` [PATCH v10 bpf-next 16/18] bpf: update xdp_adjust_tail selftest to include multi-buffer Lorenzo Bianconi
2021-07-28  9:38 ` [PATCH v10 bpf-next 17/18] net: xdp: introduce bpf_xdp_adjust_data helper Lorenzo Bianconi
2021-07-28  9:38 ` [PATCH v10 bpf-next 18/18] bpf: add bpf_xdp_adjust_data selftest Lorenzo Bianconi
2021-07-28  9:47 ` [PATCH v10 bpf-next 00/18] mvneta: introduce XDP multi-buffer support Lorenzo Bianconi
2021-07-30 23:00   ` Andrii Nakryiko
2021-08-02 14:42     ` Lorenzo Bianconi

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=cover.1627463617.git.lorenzo@kernel.org \
    --to=lorenzo@kernel.org \
    --cc=alexander.duyck@gmail.com \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=brouer@redhat.com \
    --cc=daniel@iogearbox.net \
    --cc=davem@davemloft.net \
    --cc=dsahern@kernel.org \
    --cc=echaudro@redhat.com \
    --cc=jasowang@redhat.com \
    --cc=john.fastabend@gmail.com \
    --cc=kuba@kernel.org \
    --cc=lorenzo.bianconi@redhat.com \
    --cc=maciej.fijalkowski@intel.com \
    --cc=magnus.karlsson@intel.com \
    --cc=netdev@vger.kernel.org \
    --cc=saeed@kernel.org \
    --cc=shayagr@amazon.com \
    --cc=tirthendu.sarkar@intel.com \
    --cc=toke@redhat.com \
    --subject='Re: [PATCH v10 bpf-next 00/18] mvneta: introduce XDP multi-buffer support' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).