gro.py

#!/usr/bin/env python3
# SPDX-License-Identifier: GPL-2.0

"""
GRO (Generic Receive Offload) conformance tests.

Validates that GRO coalescing works correctly by running the gro
binary in different configurations and checking for correct packet
coalescing behavior.

Test cases:
  - data: Data packets with same size/headers and correct seq numbers coalesce
  - ack: Pure ACK packets do not coalesce
  - flags: Packets with PSH, SYN, URG, RST flags do not coalesce
  - tcp: Packets with incorrect checksum, non-consecutive seqno don't coalesce
  - ip: Packets with different ECN, TTL, TOS, or IP options don't coalesce
  - large: Packets larger than GRO_MAX_SIZE don't coalesce
"""

import os
from lib.py import ksft_run, ksft_exit, ksft_pr
from lib.py import NetDrvEpEnv, KsftXfailEx
from lib.py import cmd, defer, bkg, ip
from lib.py import ksft_variants


def _resolve_dmac(cfg, ipver):
    """
    Find the destination MAC address remote host should use to send packets
    towards the local host. It may be a router / gateway address.
    """

    attr = "dmac" + ipver
    # Cache the response across test cases
    if hasattr(cfg, attr):
        return getattr(cfg, attr)

    route = ip(f"-{ipver} route get {cfg.addr_v[ipver]}",
               json=True, host=cfg.remote)[0]
    gw = route.get("gateway")
    # Local L2 segment, address directly
    if not gw:
        setattr(cfg, attr, cfg.dev['address'])
        return getattr(cfg, attr)

    # ping to make sure neighbor is resolved,
    # bind to an interface, for v6 the GW is likely link local
    cmd(f"ping -c1 -W0 -I{cfg.remote_ifname} {gw}", host=cfg.remote)

    neigh = ip(f"neigh get {gw} dev {cfg.remote_ifname}",
               json=True, host=cfg.remote)[0]
    setattr(cfg, attr, neigh['lladdr'])
    return getattr(cfg, attr)


def _write_defer_restore(cfg, path, val, defer_undo=False):
    with open(path, "r", encoding="utf-8") as fp:
        orig_val = fp.read().strip()
        if str(val) == orig_val:
            return
    with open(path, "w", encoding="utf-8") as fp:
        fp.write(val)
    if defer_undo:
        defer(_write_defer_restore, cfg, path, orig_val)


def _set_mtu_restore(dev, mtu, host):
    if dev['mtu'] < mtu:
        ip(f"link set dev {dev['ifname']} mtu {mtu}", host=host)
        defer(ip, f"link set dev {dev['ifname']} mtu {dev['mtu']}", host=host)


def _setup(cfg, test_name):
    """ Setup hardware loopback mode for GRO testing. """

    if not hasattr(cfg, "bin_remote"):
        cfg.bin_local = cfg.test_dir / "gro"
        cfg.bin_remote = cfg.remote.deploy(cfg.bin_local)

    # "large" test needs at least 4k MTU
    if test_name == "large":
        _set_mtu_restore(cfg.dev, 4096, None)
        _set_mtu_restore(cfg.remote_dev, 4096, cfg.remote)

    flush_path = f"/sys/class/net/{cfg.ifname}/gro_flush_timeout"
    irq_path = f"/sys/class/net/{cfg.ifname}/napi_defer_hard_irqs"

    _write_defer_restore(cfg, flush_path, "200000", defer_undo=True)
    _write_defer_restore(cfg, irq_path, "10", defer_undo=True)

    try:
        # Disable TSO for local tests
        cfg.require_nsim()  # will raise KsftXfailEx if not running on nsim

        cmd(f"ethtool -K {cfg.ifname} gro on tso off")
        cmd(f"ethtool -K {cfg.remote_ifname} gro on tso off", host=cfg.remote)
    except KsftXfailEx:
        pass

def _gro_variants():
    """Generator that yields all combinations of protocol and test types."""

    for protocol in ["ipv4", "ipv6", "ipip"]:
        for test_name in ["data", "ack", "flags", "tcp", "ip", "large"]:
            yield protocol, test_name


@ksft_variants(_gro_variants())
def test(cfg, protocol, test_name):
    """Run a single GRO test with retries."""

    ipver = "6" if protocol[-1] == "6" else "4"
    cfg.require_ipver(ipver)

    _setup(cfg, test_name)

    base_cmd_args = [
        f"--{protocol}",
        f"--dmac {_resolve_dmac(cfg, ipver)}",
        f"--smac {cfg.remote_dev['address']}",
        f"--daddr {cfg.addr_v[ipver]}",
        f"--saddr {cfg.remote_addr_v[ipver]}",
        f"--test {test_name}",
        "--verbose"
    ]
    base_args = " ".join(base_cmd_args)

    # Each test is run 6 times to deflake, because given the receive timing,
    # not all packets that should coalesce will be considered in the same flow
    # on every try.
    max_retries = 6
    for attempt in range(max_retries):
        rx_cmd = f"{cfg.bin_local} {base_args} --rx --iface {cfg.ifname}"
        tx_cmd = f"{cfg.bin_remote} {base_args} --iface {cfg.remote_ifname}"

        fail_now = attempt >= max_retries - 1

        with bkg(rx_cmd, ksft_ready=True, exit_wait=True,
                 fail=fail_now) as rx_proc:
            cmd(tx_cmd, host=cfg.remote)

        if rx_proc.ret == 0:
            return

        ksft_pr(rx_proc.stdout.strip().replace('\n', '\n# '))
        ksft_pr(rx_proc.stderr.strip().replace('\n', '\n# '))

        if test_name == "large" and os.environ.get("KSFT_MACHINE_SLOW"):
            ksft_pr(f"Ignoring {protocol}/{test_name} failure due to slow environment")
            return

        ksft_pr(f"Attempt {attempt + 1}/{max_retries} failed, retrying...")


def main() -> None:
    """ Ksft boiler plate main """

    with NetDrvEpEnv(__file__) as cfg:
        ksft_run(cases=[test], args=(cfg,))
    ksft_exit()


if __name__ == "__main__":
    main()