selftests: drv-net: test XDP, HDS auto and the ioctl path

Test XDP and HDS interaction. While at it add a test for using the IOCTL,
as that turned out to be the real culprit.

Testing bnxt:

  # NETIF=eth0 ./ksft-net-drv/drivers/net/hds.py
  KTAP version 1
  1..12
  ok 1 hds.get_hds
  ok 2 hds.get_hds_thresh
  ok 3 hds.set_hds_disable # SKIP disabling of HDS not supported by the device
  ok 4 hds.set_hds_enable
  ok 5 hds.set_hds_thresh_zero
  ok 6 hds.set_hds_thresh_max
  ok 7 hds.set_hds_thresh_gt
  ok 8 hds.set_xdp
  ok 9 hds.enabled_set_xdp
  ok 10 hds.ioctl
  ok 11 hds.ioctl_set_xdp
  ok 12 hds.ioctl_enabled_set_xdp
  # Totals: pass:11 fail:0 xfail:0 xpass:0 skip:1 error:0

and netdevsim:

  # ./ksft-net-drv/drivers/net/hds.py
  KTAP version 1
  1..12
  ok 1 hds.get_hds
  ok 2 hds.get_hds_thresh
  ok 3 hds.set_hds_disable
  ok 4 hds.set_hds_enable
  ok 5 hds.set_hds_thresh_zero
  ok 6 hds.set_hds_thresh_max
  ok 7 hds.set_hds_thresh_gt
  ok 8 hds.set_xdp
  ok 9 hds.enabled_set_xdp
  ok 10 hds.ioctl
  ok 11 hds.ioctl_set_xdp
  ok 12 hds.ioctl_enabled_set_xdp
  # Totals: pass:12 fail:0 xfail:0 xpass:0 skip:0 error:0

Netdevsim needs a sane default for tx/rx ring size.

ethtool 6.11 is needed for the --disable-netlink option.

Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Tested-by: Taehee Yoo <ap420073@gmail.com>
Link: https://patch.msgid.link/20250221025141.1132944-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/netdevsim/ethtool.c

@@ -184,9 +184,11 @@ static const struct ethtool_ops nsim_ethtool_ops = {
 
 static void nsim_ethtool_ring_init(struct netdevsim *ns)
 {
+	ns->ethtool.ring.rx_pending = 512;
 	ns->ethtool.ring.rx_max_pending = 4096;
 	ns->ethtool.ring.rx_jumbo_max_pending = 4096;
 	ns->ethtool.ring.rx_mini_max_pending = 4096;
+	ns->ethtool.ring.tx_pending = 512;
 	ns->ethtool.ring.tx_max_pending = 4096;
 }
 

tools/testing/selftests/drivers/net/hds.py

@@ -2,17 +2,54 @@
 # SPDX-License-Identifier: GPL-2.0
 
 import errno
+import os
 from lib.py import ksft_run, ksft_exit, ksft_eq, ksft_raises, KsftSkipEx
-from lib.py import EthtoolFamily, NlError
+from lib.py import CmdExitFailure, EthtoolFamily, NlError
 from lib.py import NetDrvEnv
+from lib.py import defer, ethtool, ip
 
-def get_hds(cfg, netnl) -> None:
+
+def _get_hds_mode(cfg, netnl) -> str:
     try:
         rings = netnl.rings_get({'header': {'dev-index': cfg.ifindex}})
     except NlError as e:
         raise KsftSkipEx('ring-get not supported by device')
     if 'tcp-data-split' not in rings:
         raise KsftSkipEx('tcp-data-split not supported by device')
+    return rings['tcp-data-split']
+
+
+def _xdp_onoff(cfg):
+    test_dir = os.path.dirname(os.path.realpath(__file__))
+    prog = test_dir + "/../../net/lib/xdp_dummy.bpf.o"
+    ip("link set dev %s xdp obj %s sec xdp" %
+       (cfg.ifname, prog))
+    ip("link set dev %s xdp off" % cfg.ifname)
+
+
+def _ioctl_ringparam_modify(cfg, netnl) -> None:
+    """
+    Helper for performing a hopefully unimportant IOCTL SET.
+    IOCTL does not support HDS, so it should not affect the HDS config.
+    """
+    try:
+        rings = netnl.rings_get({'header': {'dev-index': cfg.ifindex}})
+    except NlError as e:
+        raise KsftSkipEx('ring-get not supported by device')
+
+    if 'tx' not in rings:
+        raise KsftSkipEx('setting Tx ring size not supported')
+
+    try:
+        ethtool(f"--disable-netlink -G {cfg.ifname} tx {rings['tx'] // 2}")
+    except CmdExitFailure as e:
+        ethtool(f"--disable-netlink -G {cfg.ifname} tx {rings['tx'] * 2}")
+    defer(ethtool, f"-G {cfg.ifname} tx {rings['tx']}")
+
+
+def get_hds(cfg, netnl) -> None:
+    _get_hds_mode(cfg, netnl)
+
 
 def get_hds_thresh(cfg, netnl) -> None:
     try:
@@ -104,6 +141,103 @@ def set_hds_thresh_gt(cfg, netnl) -> None:
         netnl.rings_set({'header': {'dev-index': cfg.ifindex}, 'hds-thresh': hds_gt})
     ksft_eq(e.exception.nl_msg.error, -errno.EINVAL)
 
+
+def set_xdp(cfg, netnl) -> None:
+    """
+    Enable single-buffer XDP on the device.
+    When HDS is in "auto" / UNKNOWN mode, XDP installation should work.
+    """
+    mode = _get_hds_mode(cfg, netnl)
+    if mode == 'enabled':
+        netnl.rings_set({'header': {'dev-index': cfg.ifindex},
+                         'tcp-data-split': 'unknown'})
+
+    _xdp_onoff(cfg)
+
+
+def enabled_set_xdp(cfg, netnl) -> None:
+    """
+    Enable single-buffer XDP on the device.
+    When HDS is in "enabled" mode, XDP installation should not work.
+    """
+    _get_hds_mode(cfg, netnl)
+    netnl.rings_set({'header': {'dev-index': cfg.ifindex},
+                     'tcp-data-split': 'enabled'})
+
+    defer(netnl.rings_set, {'header': {'dev-index': cfg.ifindex},
+                            'tcp-data-split': 'unknown'})
+
+    with ksft_raises(CmdExitFailure) as e:
+        _xdp_onoff(cfg)
+
+
+def set_xdp(cfg, netnl) -> None:
+    """
+    Enable single-buffer XDP on the device.
+    When HDS is in "auto" / UNKNOWN mode, XDP installation should work.
+    """
+    mode = _get_hds_mode(cfg, netnl)
+    if mode == 'enabled':
+        netnl.rings_set({'header': {'dev-index': cfg.ifindex},
+                         'tcp-data-split': 'unknown'})
+
+    _xdp_onoff(cfg)
+
+
+def enabled_set_xdp(cfg, netnl) -> None:
+    """
+    Enable single-buffer XDP on the device.
+    When HDS is in "enabled" mode, XDP installation should not work.
+    """
+    _get_hds_mode(cfg, netnl)  # Trigger skip if not supported
+
+    netnl.rings_set({'header': {'dev-index': cfg.ifindex},
+                     'tcp-data-split': 'enabled'})
+    defer(netnl.rings_set, {'header': {'dev-index': cfg.ifindex},
+                            'tcp-data-split': 'unknown'})
+
+    with ksft_raises(CmdExitFailure) as e:
+        _xdp_onoff(cfg)
+
+
+def ioctl(cfg, netnl) -> None:
+    mode1 = _get_hds_mode(cfg, netnl)
+    _ioctl_ringparam_modify(cfg, netnl)
+    mode2 = _get_hds_mode(cfg, netnl)
+
+    ksft_eq(mode1, mode2)
+
+
+def ioctl_set_xdp(cfg, netnl) -> None:
+    """
+    Like set_xdp(), but we perturb the settings via the legacy ioctl.
+    """
+    mode = _get_hds_mode(cfg, netnl)
+    if mode == 'enabled':
+        netnl.rings_set({'header': {'dev-index': cfg.ifindex},
+                         'tcp-data-split': 'unknown'})
+
+    _ioctl_ringparam_modify(cfg, netnl)
+
+    _xdp_onoff(cfg)
+
+
+def ioctl_enabled_set_xdp(cfg, netnl) -> None:
+    """
+    Enable single-buffer XDP on the device.
+    When HDS is in "enabled" mode, XDP installation should not work.
+    """
+    _get_hds_mode(cfg, netnl)  # Trigger skip if not supported
+
+    netnl.rings_set({'header': {'dev-index': cfg.ifindex},
+                     'tcp-data-split': 'enabled'})
+    defer(netnl.rings_set, {'header': {'dev-index': cfg.ifindex},
+                            'tcp-data-split': 'unknown'})
+
+    with ksft_raises(CmdExitFailure) as e:
+        _xdp_onoff(cfg)
+
+
 def main() -> None:
     with NetDrvEnv(__file__, queue_count=3) as cfg:
         ksft_run([get_hds,
@@ -112,7 +246,12 @@ def main() -> None:
                   set_hds_enable,
                   set_hds_thresh_zero,
                   set_hds_thresh_max,
-                  set_hds_thresh_gt],
+                  set_hds_thresh_gt,
+                  set_xdp,
+                  enabled_set_xdp,
+                  ioctl,
+                  ioctl_set_xdp,
+                  ioctl_enabled_set_xdp],
                  args=(cfg, EthtoolFamily()))
     ksft_exit()
 

tools/testing/selftests/net/lib/Makefile

@@ -9,7 +9,10 @@ TEST_FILES := ../../../../../Documentation/netlink/specs
 TEST_FILES += ../../../../net/ynl
 
 TEST_GEN_FILES += csum
+TEST_GEN_FILES += $(patsubst %.c,%.o,$(wildcard *.bpf.c))
 
 TEST_INCLUDES := $(wildcard py/*.py sh/*.sh)
 
 include ../../lib.mk
+
+include ../bpf.mk

tools/testing/selftests/net/lib/xdp_dummy.bpf.c

@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define KBUILD_MODNAME "xdp_dummy"
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+SEC("xdp")
+int xdp_dummy_prog(struct xdp_md *ctx)
+{
+	return XDP_PASS;
+}
+
+char _license[] SEC("license") = "GPL";