[dpdk-dev] [PATCH v3 0/2] TAP RSS eBPF cover letter

[Jason Wang]

On 2018年01月10日 15:06, Ophir Munk wrote:
> The patches of TAP RSS eBPF follow the RFC on this issue
> https://dpdk.org/dev/patchwork/patch/31781/
>
> v3 changes with respect to v2
> =============================
> * Add support for IPv6 RSS in BPF program
> * Bug fixes
> * Updated compatibility to kernel versions:
>    eBPF requires Linux version 4.9 configured with BPF
> * New license header (SPDX) for newly added files
>
> v2 changes with respect to v1
> =============================
> * v2 has new commits organization (3 --> 2)
> * BPF program was revised. It is successfully tested on
>    IPv4 L3 L4 layers (compatible to mlx4 device)
> * Licensing: no comments received for using "Dual BSD/GPL"
>    string during BPF program loading to the kernel.
>    (v1 and v2 are using the same license strings)
>    Any comments are welcome.
> * Compatibility to kernel versions:
>    eBPF requires Linux version 4.2 configured with BPF. TAP PMD will
>    successfully compile on systems with old or non-BPF configured kernels.
>    During compilation time the required Linux headers are searched for.
>    If they are not present missing definitions are locally added
>    (tap_autoconf.h).
>    If the kernel cannot support a BPF operation - at runtime it will
>    gracefully reject the netlink message (with BPF) sent to it.
>
> Commit #1:
> net/tap: add eBPF instructions to TAP device
> ===========================================
>    This commit introduces BPF program (tap_bpf_program.c)
>    with a classifier and an action sections.
>    The current implementation calculates RSS hash
>    over L3 addresses and L4 ports.
>    BPF program compilation is not part of dpdk compilation.
>    This commit includes the eBPF machine instructions
>    in the format of C arrays (tap_bpf_insns.c).
>
>    The option to update the BPF program and download new machine
>    instructions will be described in another commit.
>
> Commit #2:
> net/tap: implement RSS with eBPF classifier and action
> ======================================================
> This commit builds and sends netlink messages to the kernel
> that include BPF programs.
> There is a single BPF classifier for each TAP queue. Packets
> marked with an RSS queue will be directed to this queue using a traffic
> control with "skbedit" action otherwise they will be pipelined to
> the following rules.
> There is a single BPF action for each RSS rule (may add more
> to support IPv6).
> The action is to calculate Toeplitz hash based on L3 addresses and L4 ports,
> mark the packet with the RSS queue according the resulting hash,
> then reclassify the packet.
> Ophir Munk (2):
>    net/tap: add eBPF instructions to TAP device
>    net/tap: implement RSS with eBPF classifier and action
>
>   drivers/net/tap/Makefile          |   31 +
>   drivers/net/tap/rte_eth_tap.h     |    9 +-
>   drivers/net/tap/tap_bpf.h         |   92 ++
>   drivers/net/tap/tap_bpf_insns.c   | 1905 +++++++++++++++++++++++++++++++++++++
>   drivers/net/tap/tap_bpf_program.c |  221 +++++
>   drivers/net/tap/tap_flow.c        |  635 +++++++++++--
>   drivers/net/tap/tap_flow.h        |   15 +
>   drivers/net/tap/tap_rss.h         |   32 +
>   drivers/net/tap/tap_tcmsgs.h      |    4 +
>   9 files changed, 2848 insertions(+), 96 deletions(-)
>   create mode 100644 drivers/net/tap/tap_bpf.h
>   create mode 100644 drivers/net/tap/tap_bpf_insns.c
>   create mode 100644 drivers/net/tap/tap_bpf_program.c
>   create mode 100644 drivers/net/tap/tap_rss.h
>

TAP will support eBPF classification directly [1] through eBPF socket 
filter. Compare to tc-bpf, it was more portable for other backends (e.g 
macvtap).

[1] 
https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/commit/drivers/net/tun.c?id=96f84061620c6325a2ca9a9a05b410e6461d03c3

Thanks