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[v10,bpf-next,00/18] mvneta: introduce XDP multi-buffer support

Message ID cover.1627463617.git.lorenzo@kernel.org
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Series mvneta: introduce XDP multi-buffer support | expand

Message

Lorenzo Bianconi July 28, 2021, 9:38 a.m. UTC
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

Comments

Lorenzo Bianconi July 28, 2021, 9:47 a.m. UTC | #1
> From: Lorenzo Bianconi <lorenzo@kernel.org>
> 
> 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.

I sent the cover-letter. Sorry for the noise.

Regards,
Lorenzo

> 
> 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
>
Andrii Nakryiko July 30, 2021, 11 p.m. UTC | #2
On Wed, Jul 28, 2021 at 2:47 AM Lorenzo Bianconi
<lorenzo.bianconi@redhat.com> wrote:
>

> > From: Lorenzo Bianconi <lorenzo@kernel.org>

> >

> > 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.

>

> I sent the cover-letter. Sorry for the noise.

>

> Regards,

> Lorenzo

>

> >

> > 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.

> >


Seems like your changes are breaking selftests in no-alu32 mode ([0]).
Please take a look.

  [0] https://github.com/kernel-patches/bpf/runs/3197530080?check_suite_focus=true

> > 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

> >
Lorenzo Bianconi Aug. 2, 2021, 2:42 p.m. UTC | #3
[...]
> > > bpf_xdp_adjust_tail and bpf_xdp_copy helpers have been modified to take into

> > > account xdp multi-buff frames.

> > >

> 

> Seems like your changes are breaking selftests in no-alu32 mode ([0]).

> Please take a look.

> 

>   [0] https://github.com/kernel-patches/bpf/runs/3197530080?check_suite_focus=true


Hi Andrii,

for no-alu32 mode, it seems the verifiers is complaining when the program is
trying to access the packet payload using the updated value for offset:

if (data[offset] != 0xaa) /* marker *
 ...

as double check, if I use the proper constant value for
offset (1480 = 5000 (original offset) - 3520 (buff0 length))
the test if fine. I need to understand the root cause of the issue.

Regards,
Lorenzo

> 

> > > 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

> > >