netdev - Re: [PATCH net-next 2/2] selftests: drv-net: gro: run the test against HW GRO and LRO

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <willemdebruijn.kernel.468ae2cb7a74@gmail.com>
Date: Fri, 28 Nov 2025 15:42:40 -0500
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: Jakub Kicinski <kuba@...nel.org>, 
 davem@...emloft.net
Cc: netdev@...r.kernel.org, 
 edumazet@...gle.com, 
 pabeni@...hat.com, 
 andrew+netdev@...n.ch, 
 horms@...nel.org, 
 willemdebruijn.kernel@...il.com, 
 Jakub Kicinski <kuba@...nel.org>, 
 shuah@...nel.org, 
 sdf@...ichev.me, 
 linux-kselftest@...r.kernel.org
Subject: Re: [PATCH net-next 2/2] selftests: drv-net: gro: run the test
 against HW GRO and LRO

Jakub Kicinski wrote:
> Run the test against HW GRO and LRO. NICs I have pass the base cases.
> Interestingly all are happy to build GROs larger than 64k.
> 
> Signed-off-by: Jakub Kicinski <kuba@...nel.org>

Reviewed-by: Willem de Bruijn <willemb@...gle.com>

> ---
> CC: shuah@...nel.org
> CC: sdf@...ichev.me
> CC: linux-kselftest@...r.kernel.org
> ---
>  tools/testing/selftests/drivers/net/gro.py | 50 ++++++++++++++++------
>  1 file changed, 36 insertions(+), 14 deletions(-)
> 
> diff --git a/tools/testing/selftests/drivers/net/gro.py b/tools/testing/selftests/drivers/net/gro.py
> index 6d633bdc7e67..ea7070b033d4 100755
> --- a/tools/testing/selftests/drivers/net/gro.py
> +++ b/tools/testing/selftests/drivers/net/gro.py
> @@ -91,7 +91,7 @@ from lib.py import ksft_variants
>      defer(ethtool, " ".join(old), host=host)
>  
>  
> -def _setup(cfg, test_name):
> +def _setup(cfg, mode, test_name):
>      """ Setup hardware loopback mode for GRO testing. """
>  
>      if not hasattr(cfg, "bin_remote"):
> @@ -108,16 +108,37 @@ from lib.py import ksft_variants
>          _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"
> +    if mode == "sw":
> +        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)
> +        _write_defer_restore(cfg, flush_path, "200000", defer_undo=True)
> +        _write_defer_restore(cfg, irq_path, "10", defer_undo=True)
>  
> -    _set_ethtool_feat(cfg.ifname, cfg.feat,
> -                      {"generic-receive-offload": True,
> -                       "rx-gro-hw": False,
> -                       "large-receive-offload": False})
> +        _set_ethtool_feat(cfg.ifname, cfg.feat,
> +                          {"generic-receive-offload": True,
> +                           "rx-gro-hw": False,
> +                           "large-receive-offload": False})
> +    elif mode == "hw":
> +        # The only way to get HW GRO but elide SW GRO is to install
> +        # a dummy XDP generic program. Disabling SW GRO as a feature
> +        # would also disable HW GRO.
> +        prog = cfg.net_lib_dir / "xdp_dummy.bpf.o"
> +        ip(f"link set dev {cfg.ifname} xdpgeneric obj {prog} sec xdp")
> +        defer(ip, f"link set dev {cfg.ifname} xdpgeneric off")
> +
> +        # Attaching XDP may change features, fetch the latest state
> +        feat = ethtool(f"-k {cfg.ifname}", json=True)[0]
> +
> +        _set_ethtool_feat(cfg.ifname, feat,
> +                          {"generic-receive-offload": True,
> +                           "rx-gro-hw": True,
> +                           "large-receive-offload": False})
> +    elif mode == "lro":
> +        _set_ethtool_feat(cfg.ifname, cfg.feat,
> +                          {"generic-receive-offload": False,

So GRO off disables HW_GRO, but not LRO? That difference is behavior
is confusing. Could we still see this as a regression and make the
ethtool HW_GRO feature equally independent from SW_GRO?

> +                           "rx-gro-hw": False,
> +                           "large-receive-offload": True})
>  
>      try:
>          # Disable TSO for local tests
> @@ -132,19 +153,20 @@ from lib.py import ksft_variants
>  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
> +    for mode in ["sw", "hw", "lro"]:
> +        for protocol in ["ipv4", "ipv6", "ipip"]:
> +            for test_name in ["data", "ack", "flags", "tcp", "ip", "large"]:
> +                yield mode, protocol, test_name
>  
>  
>  @ksft_variants(_gro_variants())
> -def test(cfg, protocol, test_name):
> +def test(cfg, mode, 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)
> +    _setup(cfg, mode, test_name)
>  
>      base_cmd_args = [
>          f"--{protocol}",
> -- 
> 2.51.1
>