[bpf-next,0/8] Add support for transmitting packets using XDP in bpf_prog_run()

Message

Toke Høiland-Jørgensen Dec. 2, 2021, 12:02 a.m. UTC

This series adds support for transmitting packets using XDP in
bpf_prog_run(), by enabling the xdp_do_redirect() callback so XDP programs
can perform "real" redirects to devices or maps, using an opt-in flag when
executing the program.

The primary use case for this is testing the redirect map types and the
ndo_xdp_xmit driver operation without generating external traffic. But it
turns out to also be useful for creating a programmable traffic generator.
The last patch adds a sample traffic generator to bpf/samples, which
can transmit up to 11.5 Mpps/core on my test machine.

To transmit the frames, the new mode instantiates a page_pool structure in
bpf_prog_run() and initialises the pages with the data passed in by
userspace. These pages can then be redirected using the normal redirection
mechanism, and the existing page_pool code takes care of returning and
recycling them. The setup is optimised for high performance with a high
number of repetitions to support stress testing and the traffic generator
use case; see patch 6 for details.

The series is structured as follows: Patches 1-2 adds a few features to
page_pool that are needed for the usage in bpf_prog_run(). Similarly,
patches 3-5 performs a couple of preparatory refactorings of the XDP
redirect and memory management code. Patch 6 adds the support to
bpf_prog_run() itself, patch 7 adds a selftest, and patch 8 adds the
traffic generator example to samples/bpf.

Toke Høiland-Jørgensen (8):
  page_pool: Add callback to init pages when they are allocated
  page_pool: Store the XDP mem id
  xdp: Allow registering memory model without rxq reference
  xdp: Move conversion to xdp_frame out of map functions
  xdp: add xdp_do_redirect_frame() for pre-computed xdp_frames
  bpf: Add XDP_REDIRECT support to XDP for bpf_prog_run()
  selftests/bpf: Add selftest for XDP_REDIRECT in bpf_prog_run()
  samples/bpf: Add xdp_trafficgen sample

 include/linux/bpf.h                           |  20 +-
 include/linux/filter.h                        |   4 +
 include/net/page_pool.h                       |  11 +-
 include/net/xdp.h                             |   3 +
 include/uapi/linux/bpf.h                      |   2 +
 kernel/bpf/Kconfig                            |   1 +
 kernel/bpf/cpumap.c                           |   8 +-
 kernel/bpf/devmap.c                           |  32 +-
 net/bpf/test_run.c                            | 197 +++++++-
 net/core/filter.c                             |  41 +-
 net/core/page_pool.c                          |   6 +-
 net/core/xdp.c                                |  94 ++--
 samples/bpf/.gitignore                        |   1 +
 samples/bpf/Makefile                          |   4 +
 samples/bpf/xdp_redirect.bpf.c                |  34 ++
 samples/bpf/xdp_trafficgen_user.c             | 444 ++++++++++++++++++
 tools/include/uapi/linux/bpf.h                |   2 +
 .../bpf/prog_tests/xdp_do_redirect.c          |  74 +++
 .../bpf/progs/test_xdp_do_redirect.c          |  34 ++
 19 files changed, 920 insertions(+), 92 deletions(-)
 create mode 100644 samples/bpf/xdp_trafficgen_user.c
 create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_do_redirect.c

Comments

John Fastabend Dec. 9, 2021, 12:54 a.m. UTC | #1

Toke Høiland-Jørgensen wrote:
> This series adds support for transmitting packets using XDP in
> bpf_prog_run(), by enabling the xdp_do_redirect() callback so XDP programs
> can perform "real" redirects to devices or maps, using an opt-in flag when
> executing the program.
> 
> The primary use case for this is testing the redirect map types and the
> ndo_xdp_xmit driver operation without generating external traffic. But it
> turns out to also be useful for creating a programmable traffic generator.
> The last patch adds a sample traffic generator to bpf/samples, which
> can transmit up to 11.5 Mpps/core on my test machine.
> 
> To transmit the frames, the new mode instantiates a page_pool structure in
> bpf_prog_run() and initialises the pages with the data passed in by
> userspace. These pages can then be redirected using the normal redirection
> mechanism, and the existing page_pool code takes care of returning and
> recycling them. The setup is optimised for high performance with a high
> number of repetitions to support stress testing and the traffic generator
> use case; see patch 6 for details.
> 
> The series is structured as follows: Patches 1-2 adds a few features to
> page_pool that are needed for the usage in bpf_prog_run(). Similarly,
> patches 3-5 performs a couple of preparatory refactorings of the XDP
> redirect and memory management code. Patch 6 adds the support to
> bpf_prog_run() itself, patch 7 adds a selftest, and patch 8 adds the
> traffic generator example to samples/bpf.

Overall looks pretty good. Couple questions in the series though.

Thanks!
John

Toke Høiland-Jørgensen Dec. 9, 2021, 4:01 p.m. UTC | #2

John Fastabend <[e-mail]> writes:

> Toke Høiland-Jørgensen wrote:
>> This series adds support for transmitting packets using XDP in
>> bpf_prog_run(), by enabling the xdp_do_redirect() callback so XDP programs
>> can perform "real" redirects to devices or maps, using an opt-in flag when
>> executing the program.
>> 
>> The primary use case for this is testing the redirect map types and the
>> ndo_xdp_xmit driver operation without generating external traffic. But it
>> turns out to also be useful for creating a programmable traffic generator.
>> The last patch adds a sample traffic generator to bpf/samples, which
>> can transmit up to 11.5 Mpps/core on my test machine.
>> 
>> To transmit the frames, the new mode instantiates a page_pool structure in
>> bpf_prog_run() and initialises the pages with the data passed in by
>> userspace. These pages can then be redirected using the normal redirection
>> mechanism, and the existing page_pool code takes care of returning and
>> recycling them. The setup is optimised for high performance with a high
>> number of repetitions to support stress testing and the traffic generator
>> use case; see patch 6 for details.
>> 
>> The series is structured as follows: Patches 1-2 adds a few features to
>> page_pool that are needed for the usage in bpf_prog_run(). Similarly,
>> patches 3-5 performs a couple of preparatory refactorings of the XDP
>> redirect and memory management code. Patch 6 adds the support to
>> bpf_prog_run() itself, patch 7 adds a selftest, and patch 8 adds the
>> traffic generator example to samples/bpf.
>
> Overall looks pretty good. Couple questions in the series though.

Yay! Thank you for the review! Will reply to each of those...

-Toke