[PATCH net-next v4 5/6] selftests: net: move common xdp.py functions into lib

[PATCH net-next v4 5/6] selftests: net: move common xdp.py functions into lib

[Chris J Arges]

This moves a few functions which can be useful to other python programs
that manipulate XDP programs. This also refactors xdp.py to use the
refactored functions.

Reviewed-by: Joe Damato <joe@dama.to>
Signed-off-by: Chris J Arges <carges@cloudflare.com>
---
v4: rebase only
---
 .../selftests/drivers/net/lib/py/__init__.py  |  2 +
 tools/testing/selftests/drivers/net/xdp.py    | 95 +++++--------------
 .../testing/selftests/net/lib/py/__init__.py  |  2 +
 tools/testing/selftests/net/lib/py/bpf.py     | 68 +++++++++++++
 4 files changed, 95 insertions(+), 72 deletions(-)
 create mode 100644 tools/testing/selftests/net/lib/py/bpf.py

diff --git a/tools/testing/selftests/drivers/net/lib/py/__init__.py b/tools/testing/selftests/drivers/net/lib/py/__init__.py
index 374d4f08dd05..2b5ec0505672 100644
--- a/tools/testing/selftests/drivers/net/lib/py/__init__.py
+++ b/tools/testing/selftests/drivers/net/lib/py/__init__.py
@@ -24,6 +24,7 @@ try:
     from net.lib.py import CmdExitFailure
     from net.lib.py import bkg, cmd, bpftool, bpftrace, defer, ethtool, \
         fd_read_timeout, ip, rand_port, rand_ports, wait_port_listen, wait_file
+    from net.lib.py import bpf_map_set, bpf_map_dump, bpf_prog_map_ids
     from net.lib.py import KsftSkipEx, KsftFailEx, KsftXfailEx
     from net.lib.py import ksft_disruptive, ksft_exit, ksft_pr, ksft_run, \
         ksft_setup, ksft_variants, KsftNamedVariant
@@ -37,6 +38,7 @@ try:
                "bkg", "cmd", "bpftool", "bpftrace", "defer", "ethtool",
                "fd_read_timeout", "ip", "rand_port", "rand_ports",
                "wait_port_listen", "wait_file",
+               "bpf_map_set", "bpf_map_dump", "bpf_prog_map_ids",
                "KsftSkipEx", "KsftFailEx", "KsftXfailEx",
                "ksft_disruptive", "ksft_exit", "ksft_pr", "ksft_run",
                "ksft_setup", "ksft_variants", "KsftNamedVariant",
diff --git a/tools/testing/selftests/drivers/net/xdp.py b/tools/testing/selftests/drivers/net/xdp.py
index e54df158dfe9..10d821156db1 100755
--- a/tools/testing/selftests/drivers/net/xdp.py
+++ b/tools/testing/selftests/drivers/net/xdp.py
@@ -16,7 +16,8 @@ from lib.py import KsftNamedVariant, ksft_variants
 from lib.py import KsftFailEx, NetDrvEpEnv
 from lib.py import EthtoolFamily, NetdevFamily, NlError
 from lib.py import bkg, cmd, rand_port, wait_port_listen
-from lib.py import ip, bpftool, defer
+from lib.py import ip, defer
+from lib.py import bpf_map_set, bpf_map_dump, bpf_prog_map_ids
 
 
 class TestConfig(Enum):
@@ -122,47 +123,11 @@ def _load_xdp_prog(cfg, bpf_info):
     xdp_info = ip(f"-d link show dev {cfg.ifname}", json=True)[0]
     prog_info["id"] = xdp_info["xdp"]["prog"]["id"]
     prog_info["name"] = xdp_info["xdp"]["prog"]["name"]
-    prog_id = prog_info["id"]
-
-    map_ids = bpftool(f"prog show id {prog_id}", json=True)["map_ids"]
-    prog_info["maps"] = {}
-    for map_id in map_ids:
-        name = bpftool(f"map show id {map_id}", json=True)["name"]
-        prog_info["maps"][name] = map_id
+    prog_info["maps"] = bpf_prog_map_ids(prog_info["id"])
 
     return prog_info
 
 
-def format_hex_bytes(value):
-    """
-    Helper function that converts an integer into a formatted hexadecimal byte string.
-
-    Args:
-        value: An integer representing the number to be converted.
-
-    Returns:
-        A string representing hexadecimal equivalent of value, with bytes separated by spaces.
-    """
-    hex_str = value.to_bytes(4, byteorder='little', signed=True)
-    return ' '.join(f'{byte:02x}' for byte in hex_str)
-
-
-def _set_xdp_map(map_name, key, value):
-    """
-    Updates an XDP map with a given key-value pair using bpftool.
-
-    Args:
-        map_name: The name of the XDP map to update.
-        key: The key to update in the map, formatted as a hexadecimal string.
-        value: The value to associate with the key, formatted as a hexadecimal string.
-    """
-    key_formatted = format_hex_bytes(key)
-    value_formatted = format_hex_bytes(value)
-    bpftool(
-        f"map update name {map_name} key hex {key_formatted} value hex {value_formatted}"
-    )
-
-
 def _get_stats(xdp_map_id):
     """
     Retrieves and formats statistics from an XDP map.
@@ -177,25 +142,11 @@ def _get_stats(xdp_map_id):
     Raises:
         KsftFailEx: If the stats retrieval fails.
     """
-    stats_dump = bpftool(f"map dump id {xdp_map_id}", json=True)
-    if not stats_dump:
+    stats = bpf_map_dump(xdp_map_id)
+    if not stats:
         raise KsftFailEx(f"Failed to get stats for map {xdp_map_id}")
 
-    stats_formatted = {}
-    for key in range(0, 5):
-        val = stats_dump[key]["formatted"]["value"]
-        if stats_dump[key]["formatted"]["key"] == XDPStats.RX.value:
-            stats_formatted[XDPStats.RX.value] = val
-        elif stats_dump[key]["formatted"]["key"] == XDPStats.PASS.value:
-            stats_formatted[XDPStats.PASS.value] = val
-        elif stats_dump[key]["formatted"]["key"] == XDPStats.DROP.value:
-            stats_formatted[XDPStats.DROP.value] = val
-        elif stats_dump[key]["formatted"]["key"] == XDPStats.TX.value:
-            stats_formatted[XDPStats.TX.value] = val
-        elif stats_dump[key]["formatted"]["key"] == XDPStats.ABORT.value:
-            stats_formatted[XDPStats.ABORT.value] = val
-
-    return stats_formatted
+    return stats
 
 
 def _test_pass(cfg, bpf_info, msg_sz):
@@ -211,8 +162,8 @@ def _test_pass(cfg, bpf_info, msg_sz):
     prog_info = _load_xdp_prog(cfg, bpf_info)
     port = rand_port()
 
-    _set_xdp_map("map_xdp_setup", TestConfig.MODE.value, XDPAction.PASS.value)
-    _set_xdp_map("map_xdp_setup", TestConfig.PORT.value, port)
+    bpf_map_set("map_xdp_setup", TestConfig.MODE.value, XDPAction.PASS.value)
+    bpf_map_set("map_xdp_setup", TestConfig.PORT.value, port)
 
     ksft_eq(_test_udp(cfg, port, msg_sz), True, "UDP packet exchange failed")
     stats = _get_stats(prog_info["maps"]["map_xdp_stats"])
@@ -258,8 +209,8 @@ def _test_drop(cfg, bpf_info, msg_sz):
     prog_info = _load_xdp_prog(cfg, bpf_info)
     port = rand_port()
 
-    _set_xdp_map("map_xdp_setup", TestConfig.MODE.value, XDPAction.DROP.value)
-    _set_xdp_map("map_xdp_setup", TestConfig.PORT.value, port)
+    bpf_map_set("map_xdp_setup", TestConfig.MODE.value, XDPAction.DROP.value)
+    bpf_map_set("map_xdp_setup", TestConfig.PORT.value, port)
 
     ksft_eq(_test_udp(cfg, port, msg_sz), False, "UDP packet exchange should fail")
     stats = _get_stats(prog_info["maps"]["map_xdp_stats"])
@@ -305,8 +256,8 @@ def _test_xdp_native_tx(cfg, bpf_info, payload_lens):
     prog_info = _load_xdp_prog(cfg, bpf_info)
     port = rand_port()
 
-    _set_xdp_map("map_xdp_setup", TestConfig.MODE.value, XDPAction.TX.value)
-    _set_xdp_map("map_xdp_setup", TestConfig.PORT.value, port)
+    bpf_map_set("map_xdp_setup", TestConfig.MODE.value, XDPAction.TX.value)
+    bpf_map_set("map_xdp_setup", TestConfig.PORT.value, port)
 
     expected_pkts = 0
     for payload_len in payload_lens:
@@ -454,15 +405,15 @@ def _test_xdp_native_tail_adjst(cfg, pkt_sz_lst, offset_lst):
     prog_info = _load_xdp_prog(cfg, bpf_info)
 
     # Configure the XDP map for tail adjustment
-    _set_xdp_map("map_xdp_setup", TestConfig.MODE.value, XDPAction.TAIL_ADJST.value)
-    _set_xdp_map("map_xdp_setup", TestConfig.PORT.value, port)
+    bpf_map_set("map_xdp_setup", TestConfig.MODE.value, XDPAction.TAIL_ADJST.value)
+    bpf_map_set("map_xdp_setup", TestConfig.PORT.value, port)
 
     for offset in offset_lst:
         tag = format(random.randint(65, 90), "02x")
 
-        _set_xdp_map("map_xdp_setup", TestConfig.ADJST_OFFSET.value, offset)
+        bpf_map_set("map_xdp_setup", TestConfig.ADJST_OFFSET.value, offset)
         if offset > 0:
-            _set_xdp_map("map_xdp_setup", TestConfig.ADJST_TAG.value, int(tag, 16))
+            bpf_map_set("map_xdp_setup", TestConfig.ADJST_TAG.value, int(tag, 16))
 
         for pkt_sz in pkt_sz_lst:
             test_str = "".join(random.choice(string.ascii_lowercase) for _ in range(pkt_sz))
@@ -574,8 +525,8 @@ def _test_xdp_native_head_adjst(cfg, prog, pkt_sz_lst, offset_lst):
     prog_info = _load_xdp_prog(cfg, BPFProgInfo(prog, "xdp_native.bpf.o", "xdp.frags", 9000))
     port = rand_port()
 
-    _set_xdp_map("map_xdp_setup", TestConfig.MODE.value, XDPAction.HEAD_ADJST.value)
-    _set_xdp_map("map_xdp_setup", TestConfig.PORT.value, port)
+    bpf_map_set("map_xdp_setup", TestConfig.MODE.value, XDPAction.HEAD_ADJST.value)
+    bpf_map_set("map_xdp_setup", TestConfig.PORT.value, port)
 
     hds_thresh = get_hds_thresh(cfg)
     for offset in offset_lst:
@@ -595,11 +546,11 @@ def _test_xdp_native_head_adjst(cfg, prog, pkt_sz_lst, offset_lst):
             test_str = ''.join(random.choice(string.ascii_lowercase) for _ in range(pkt_sz))
             tag = format(random.randint(65, 90), '02x')
 
-            _set_xdp_map("map_xdp_setup",
+            bpf_map_set("map_xdp_setup",
                      TestConfig.ADJST_OFFSET.value,
                      offset)
-            _set_xdp_map("map_xdp_setup", TestConfig.ADJST_TAG.value, int(tag, 16))
-            _set_xdp_map("map_xdp_setup", TestConfig.ADJST_OFFSET.value, offset)
+            bpf_map_set("map_xdp_setup", TestConfig.ADJST_TAG.value, int(tag, 16))
+            bpf_map_set("map_xdp_setup", TestConfig.ADJST_OFFSET.value, offset)
 
             recvd_str = _exchg_udp(cfg, port, test_str)
 
@@ -691,8 +642,8 @@ def test_xdp_native_qstats(cfg, act):
     prog_info = _load_xdp_prog(cfg, bpf_info)
     port = rand_port()
 
-    _set_xdp_map("map_xdp_setup", TestConfig.MODE.value, act.value)
-    _set_xdp_map("map_xdp_setup", TestConfig.PORT.value, port)
+    bpf_map_set("map_xdp_setup", TestConfig.MODE.value, act.value)
+    bpf_map_set("map_xdp_setup", TestConfig.PORT.value, port)
 
     # Discard the input, but we need a listener to avoid ICMP errors
     rx_udp = f"socat -{cfg.addr_ipver} -T 2 -u UDP-RECV:{port},reuseport " + \
diff --git a/tools/testing/selftests/net/lib/py/__init__.py b/tools/testing/selftests/net/lib/py/__init__.py
index e0c920041a58..7c81d86a7e97 100644
--- a/tools/testing/selftests/net/lib/py/__init__.py
+++ b/tools/testing/selftests/net/lib/py/__init__.py
@@ -15,6 +15,7 @@ from .nsim import NetdevSim, NetdevSimDev
 from .utils import CmdExitFailure, fd_read_timeout, cmd, bkg, defer, \
     bpftool, ip, ethtool, bpftrace, rand_port, rand_ports, wait_port_listen, \
     wait_file, tool
+from .bpf import bpf_map_set, bpf_map_dump, bpf_prog_map_ids
 from .ynl import NlError, NlctrlFamily, YnlFamily, \
     EthtoolFamily, NetdevFamily, RtnlFamily, RtnlAddrFamily
 from .ynl import NetshaperFamily, DevlinkFamily, PSPFamily, Netlink
@@ -29,6 +30,7 @@ __all__ = ["KSRC",
            "CmdExitFailure", "fd_read_timeout", "cmd", "bkg", "defer",
            "bpftool", "ip", "ethtool", "bpftrace", "rand_port", "rand_ports",
            "wait_port_listen", "wait_file", "tool",
+           "bpf_map_set", "bpf_map_dump", "bpf_prog_map_ids",
            "NetdevSim", "NetdevSimDev",
            "NetshaperFamily", "DevlinkFamily", "PSPFamily", "NlError",
            "YnlFamily", "EthtoolFamily", "NetdevFamily", "RtnlFamily",
diff --git a/tools/testing/selftests/net/lib/py/bpf.py b/tools/testing/selftests/net/lib/py/bpf.py
new file mode 100644
index 000000000000..96b29d41c34b
--- /dev/null
+++ b/tools/testing/selftests/net/lib/py/bpf.py
@@ -0,0 +1,68 @@
+# SPDX-License-Identifier: GPL-2.0
+
+"""
+BPF helper utilities for kernel selftests.
+
+Provides common operations for interacting with BPF maps and programs
+via bpftool, used by XDP and other BPF-based test files.
+"""
+
+from .utils import bpftool
+
+def format_hex_bytes(value):
+    """
+    Helper function that converts an integer into a formatted hexadecimal byte string.
+
+    Args:
+        value: An integer representing the number to be converted.
+
+    Returns:
+        A string representing hexadecimal equivalent of value, with bytes separated by spaces.
+    """
+    hex_str = value.to_bytes(4, byteorder='little', signed=True)
+    return ' '.join(f'{byte:02x}' for byte in hex_str)
+
+
+def bpf_map_set(map_name, key, value):
+    """
+    Updates an XDP map with a given key-value pair using bpftool.
+
+    Args:
+        map_name: The name of the XDP map to update.
+        key: The key to update in the map, formatted as a hexadecimal string.
+        value: The value to associate with the key, formatted as a hexadecimal string.
+    """
+    key_formatted = format_hex_bytes(key)
+    value_formatted = format_hex_bytes(value)
+    bpftool(
+        f"map update name {map_name} key hex {key_formatted} value hex {value_formatted}"
+    )
+
+def bpf_map_dump(map_id):
+    """Dump all entries of a BPF array map.
+
+    Args:
+        map_id: Numeric map ID (as returned by bpftool prog show).
+
+    Returns:
+        A dict mapping formatted key (int) to formatted value (int).
+    """
+    raw = bpftool(f"map dump id {map_id}", json=True)
+    return {e["formatted"]["key"]: e["formatted"]["value"] for e in raw}
+
+
+def bpf_prog_map_ids(prog_id):
+    """Get the map name-to-ID mapping for a loaded BPF program.
+
+    Args:
+        prog_id: Numeric program ID.
+
+    Returns:
+        A dict mapping map name (str) to map ID (int).
+    """
+    map_ids = bpftool(f"prog show id {prog_id}", json=True)["map_ids"]
+    maps = {}
+    for mid in map_ids:
+        name = bpftool(f"map show id {mid}", json=True)["name"]
+        maps[name] = mid
+    return maps
-- 
2.43.0

Re: [PATCH net-next v4 5/6] selftests: net: move common xdp.py functions into lib

[Mohsin Bashir]

> -            _set_xdp_map("map_xdp_setup",
> +            bpf_map_set("map_xdp_setup",
>                        TestConfig.ADJST_OFFSET.value,
>                        offset)
> -            _set_xdp_map("map_xdp_setup", TestConfig.ADJST_TAG.value, int(tag, 16))
> -            _set_xdp_map("map_xdp_setup", TestConfig.ADJST_OFFSET.value, offset)
> +            bpf_map_set("map_xdp_setup", TestConfig.ADJST_TAG.value, int(tag, 16))
> +            bpf_map_set("map_xdp_setup", TestConfig.ADJST_OFFSET.value, offset)

Looks like a duplicate call to adjust the offset?

> +def format_hex_bytes(value):
> +    """
> +    Helper function that converts an integer into a formatted hexadecimal byte string.
> +
> +    Args:
> +        value: An integer representing the number to be converted.
> +
> +    Returns:
> +        A string representing hexadecimal equivalent of value, with bytes separated by spaces.
> +    """
> +    hex_str = value.to_bytes(4, byteorder='little', signed=True)
> +    return ' '.join(f'{byte:02x}' for byte in hex_str)
> +
> +

Since format_hex_bytes is not exported in __init__.py, Should it be 
prefixed with _ to indicate it is private?

Re: [PATCH net-next v4 5/6] selftests: net: move common xdp.py functions into lib

[Paolo Abeni]

On 3/17/26 7:48 AM, Mohsin Bashir wrote:
>> +def format_hex_bytes(value):
>> +    """
>> +    Helper function that converts an integer into a formatted hexadecimal byte string.
>> +
>> +    Args:
>> +        value: An integer representing the number to be converted.
>> +
>> +    Returns:
>> +        A string representing hexadecimal equivalent of value, with bytes separated by spaces.
>> +    """
>> +    hex_str = value.to_bytes(4, byteorder='little', signed=True)
>> +    return ' '.join(f'{byte:02x}' for byte in hex_str)
>> +
>> +
> 
> Since format_hex_bytes is not exported in __init__.py, Should it be 
> prefixed with _ to indicate it is private?

I agree such cleanup would make sense.

/{

[PATCH net-next v4 6/6] selftests: drv-net: xdp: Add rss_hash metadata tests

[Chris J Arges]

This test loads xdp_metadata.bpf which calls bpf_xdp_metadata_rx_hash() on
incoming packets. The metadata from that packet is then sent to a BPF
map for validation. It borrows structure from xdp.py, reusing common
functions.

The test checks the device's xdp-rx-metadata-features via netlink
before running and skips on devices that do not advertise hash support.
This can be run on veth devices as well as real hardware.

The test is fairly simple and just verifies that a TCP or UDP packet can be
identified as an L4 flow. This minimal test also passes if run on a veth
device.

Signed-off-by: Chris J Arges <carges@cloudflare.com>
---
 .../testing/selftests/drivers/net/hw/Makefile |   1 +
 .../drivers/net/hw/lib/py/__init__.py         |   2 +
 .../selftests/drivers/net/hw/xdp_metadata.py  | 146 ++++++++++++++++
 .../selftests/net/lib/xdp_metadata.bpf.c      | 163 ++++++++++++++++++
 4 files changed, 312 insertions(+)
 create mode 100644 tools/testing/selftests/drivers/net/hw/xdp_metadata.py
 create mode 100644 tools/testing/selftests/net/lib/xdp_metadata.bpf.c

diff --git a/tools/testing/selftests/drivers/net/hw/Makefile b/tools/testing/selftests/drivers/net/hw/Makefile
index 91df028abfc0..fa933ce94400 100644
--- a/tools/testing/selftests/drivers/net/hw/Makefile
+++ b/tools/testing/selftests/drivers/net/hw/Makefile
@@ -41,6 +41,7 @@ TEST_PROGS = \
 	rss_input_xfrm.py \
 	toeplitz.py \
 	tso.py \
+	xdp_metadata.py \
 	xsk_reconfig.py \
 	#
 
diff --git a/tools/testing/selftests/drivers/net/hw/lib/py/__init__.py b/tools/testing/selftests/drivers/net/hw/lib/py/__init__.py
index b8d9ae282390..df4da5078c48 100644
--- a/tools/testing/selftests/drivers/net/hw/lib/py/__init__.py
+++ b/tools/testing/selftests/drivers/net/hw/lib/py/__init__.py
@@ -25,6 +25,7 @@ try:
     from net.lib.py import bkg, cmd, bpftool, bpftrace, defer, ethtool, \
         fd_read_timeout, ip, rand_port, rand_ports, wait_port_listen, \
         wait_file, tool
+    from net.lib.py import bpf_map_set, bpf_map_dump, bpf_prog_map_ids
     from net.lib.py import KsftSkipEx, KsftFailEx, KsftXfailEx
     from net.lib.py import ksft_disruptive, ksft_exit, ksft_pr, ksft_run, \
         ksft_setup, ksft_variants, KsftNamedVariant
@@ -40,6 +41,7 @@ try:
                "bkg", "cmd", "bpftool", "bpftrace", "defer", "ethtool",
                "fd_read_timeout", "ip", "rand_port", "rand_ports",
                "wait_port_listen", "wait_file", "tool",
+               "bpf_map_set", "bpf_map_dump", "bpf_prog_map_ids",
                "KsftSkipEx", "KsftFailEx", "KsftXfailEx",
                "ksft_disruptive", "ksft_exit", "ksft_pr", "ksft_run",
                "ksft_setup", "ksft_variants", "KsftNamedVariant",
diff --git a/tools/testing/selftests/drivers/net/hw/xdp_metadata.py b/tools/testing/selftests/drivers/net/hw/xdp_metadata.py
new file mode 100644
index 000000000000..33a1985356d9
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/hw/xdp_metadata.py
@@ -0,0 +1,146 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+"""
+Tests for XDP metadata kfuncs (e.g. bpf_xdp_metadata_rx_hash).
+
+These tests load device-bound XDP programs from xdp_metadata.bpf.o
+that call metadata kfuncs, send traffic, and verify the extracted
+metadata via BPF maps.
+"""
+from lib.py import ksft_run, ksft_eq, ksft_exit, ksft_ge, ksft_ne, ksft_pr
+from lib.py import KsftNamedVariant, ksft_variants
+from lib.py import CmdExitFailure, KsftSkipEx, NetDrvEpEnv
+from lib.py import NetdevFamily
+from lib.py import bkg, cmd, rand_port, wait_port_listen
+from lib.py import ip, bpftool, defer
+from lib.py import bpf_map_set, bpf_map_dump, bpf_prog_map_ids
+
+
+def _load_xdp_metadata_prog(cfg, prog_name, bpf_file="xdp_metadata.bpf.o"):
+    """Load a device-bound XDP metadata program and return prog/map info.
+
+    Returns:
+        dict with 'id', 'name', and 'maps' (name -> map_id).
+    """
+    abs_path = cfg.net_lib_dir / bpf_file
+    pin_dir = "/sys/fs/bpf/xdp_metadata_test"
+
+    cmd(f"rm -rf {pin_dir}", shell=True, fail=False)
+    cmd(f"mkdir -p {pin_dir}", shell=True)
+
+    try:
+        bpftool(f"prog loadall {abs_path} {pin_dir} type xdp "
+                f"xdpmeta_dev {cfg.ifname}")
+    except CmdExitFailure as e:
+        cmd(f"rm -rf {pin_dir}", shell=True, fail=False)
+        raise KsftSkipEx(
+            f"Failed to load device-bound XDP program '{prog_name}'"
+        ) from e
+    defer(cmd, f"rm -rf {pin_dir}", shell=True, fail=False)
+
+    pin_path = f"{pin_dir}/{prog_name}"
+    ip(f"link set dev {cfg.ifname} xdpdrv pinned {pin_path}")
+    defer(ip, f"link set dev {cfg.ifname} xdpdrv off")
+
+    xdp_info = ip(f"-d link show dev {cfg.ifname}", json=True)[0]
+    prog_id = xdp_info["xdp"]["prog"]["id"]
+
+    return {"id": prog_id,
+            "name": xdp_info["xdp"]["prog"]["name"],
+            "maps": bpf_prog_map_ids(prog_id)}
+
+
+def _send_probe(cfg, port, proto="tcp"):
+    """Send a single payload from the remote end using socat.
+
+    Args:
+        cfg: Configuration object containing network settings.
+        port: Port number for the exchange.
+        proto: Protocol to use, either "tcp" or "udp".
+    """
+    cfg.require_cmd("socat", remote=True)
+
+    if proto == "tcp":
+        rx_cmd = f"socat -{cfg.addr_ipver} -T 2 TCP-LISTEN:{port},reuseport STDOUT"
+        tx_cmd = f"echo -n rss_hash_test | socat -t 2 -u STDIN TCP:{cfg.baddr}:{port}"
+    else:
+        rx_cmd = f"socat -{cfg.addr_ipver} -T 2 -u UDP-RECV:{port},reuseport STDOUT"
+        tx_cmd = f"echo -n rss_hash_test | socat -t 2 -u STDIN UDP:{cfg.baddr}:{port}"
+
+    with bkg(rx_cmd, exit_wait=True):
+        wait_port_listen(port, proto=proto)
+        cmd(tx_cmd, host=cfg.remote, shell=True)
+
+
+# BPF map keys matching the enums in xdp_metadata.bpf.c
+_SETUP_KEY_PORT = 1
+
+_RSS_KEY_HASH = 0
+_RSS_KEY_TYPE = 1
+_RSS_KEY_PKT_CNT = 2
+_RSS_KEY_ERR_CNT = 3
+
+XDP_RSS_L4 = 0x8  # BIT(3) from enum xdp_rss_hash_type
+
+
+@ksft_variants([
+    KsftNamedVariant("tcp", "tcp"),
+    KsftNamedVariant("udp", "udp"),
+])
+def test_xdp_rss_hash(cfg, proto):
+    """Test RSS hash metadata extraction via bpf_xdp_metadata_rx_hash().
+
+    This test will only run on devices that support xdp-rx-metadata-features.
+
+    Loads the xdp_rss_hash program from xdp_metadata, sends a packet using
+    the specified protocol, and verifies that the program extracted a non-zero
+    hash with an L4 hash type.
+    """
+    dev_info = cfg.netnl.dev_get({"ifindex": cfg.ifindex})
+    rx_meta = dev_info.get("xdp-rx-metadata-features", [])
+    if "hash" not in rx_meta:
+        raise KsftSkipEx("device does not support XDP rx hash metadata")
+
+    prog_info = _load_xdp_metadata_prog(cfg, "xdp_rss_hash")
+
+    port = rand_port()
+    bpf_map_set("map_xdp_setup", _SETUP_KEY_PORT, port)
+
+    rss_map_id = prog_info["maps"]["map_rss"]
+
+    _send_probe(cfg, port, proto=proto)
+
+    rss = bpf_map_dump(rss_map_id)
+
+    pkt_cnt = rss.get(_RSS_KEY_PKT_CNT, 0)
+    err_cnt = rss.get(_RSS_KEY_ERR_CNT, 0)
+    hash_val = rss.get(_RSS_KEY_HASH, 0)
+    hash_type = rss.get(_RSS_KEY_TYPE, 0)
+
+    ksft_ge(pkt_cnt, 1, comment="should have received at least one packet")
+    ksft_eq(err_cnt, 0, comment=f"RSS hash error count: {err_cnt}")
+
+    ksft_ne(hash_val, 0,
+            f"RSS hash should be non-zero for {proto.upper()} traffic")
+    ksft_pr(f"  RSS hash: {hash_val:#010x}")
+
+    ksft_pr(f"  RSS hash type: {hash_type:#06x}")
+    ksft_ne(hash_type & XDP_RSS_L4, 0,
+            f"RSS hash type should include L4 for {proto.upper()} traffic")
+
+
+def main():
+    """Run XDP metadata kfunc tests against a real device."""
+    with NetDrvEpEnv(__file__) as cfg:
+        cfg.netnl = NetdevFamily()
+        ksft_run(
+            [
+                test_xdp_rss_hash,
+            ],
+            args=(cfg,))
+    ksft_exit()
+
+
+if __name__ == "__main__":
+    main()
diff --git a/tools/testing/selftests/net/lib/xdp_metadata.bpf.c b/tools/testing/selftests/net/lib/xdp_metadata.bpf.c
new file mode 100644
index 000000000000..f71f59215239
--- /dev/null
+++ b/tools/testing/selftests/net/lib/xdp_metadata.bpf.c
@@ -0,0 +1,163 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <stddef.h>
+#include <linux/bpf.h>
+#include <linux/in.h>
+#include <linux/if_ether.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/udp.h>
+#include <linux/tcp.h>
+#include <bpf/bpf_endian.h>
+#include <bpf/bpf_helpers.h>
+
+enum {
+	XDP_PORT = 1,
+	XDP_PROTO = 4,
+} xdp_map_setup_keys;
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 5);
+	__type(key, __u32);
+	__type(value, __s32);
+} map_xdp_setup SEC(".maps");
+
+/* RSS hash results: key 0 = hash, key 1 = hash type,
+ * key 2 = packet count, key 3 = error count.
+ */
+enum {
+	RSS_KEY_HASH = 0,
+	RSS_KEY_TYPE = 1,
+	RSS_KEY_PKT_CNT = 2,
+	RSS_KEY_ERR_CNT = 3,
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__type(key, __u32);
+	__type(value, __u32);
+	__uint(max_entries, 4);
+} map_rss SEC(".maps");
+
+/* Mirror of enum xdp_rss_hash_type from include/net/xdp.h.
+ * Needed because the enum is not part of UAPI headers.
+ */
+enum xdp_rss_hash_type {
+	XDP_RSS_L3_IPV4 = 1U << 0,
+	XDP_RSS_L3_IPV6 = 1U << 1,
+	XDP_RSS_L3_DYNHDR = 1U << 2,
+	XDP_RSS_L4 = 1U << 3,
+	XDP_RSS_L4_TCP = 1U << 4,
+	XDP_RSS_L4_UDP = 1U << 5,
+	XDP_RSS_L4_SCTP = 1U << 6,
+	XDP_RSS_L4_IPSEC = 1U << 7,
+	XDP_RSS_L4_ICMP = 1U << 8,
+};
+
+extern int bpf_xdp_metadata_rx_hash(const struct xdp_md *ctx, __u32 *hash,
+				    enum xdp_rss_hash_type *rss_type) __ksym;
+
+static __always_inline __u16 get_dest_port(void *l4, void *data_end,
+					   __u8 protocol)
+{
+	if (protocol == IPPROTO_UDP) {
+		struct udphdr *udp = l4;
+
+		if ((void *)(udp + 1) > data_end)
+			return 0;
+		return udp->dest;
+	} else if (protocol == IPPROTO_TCP) {
+		struct tcphdr *tcp = l4;
+
+		if ((void *)(tcp + 1) > data_end)
+			return 0;
+		return tcp->dest;
+	}
+
+	return 0;
+}
+
+SEC("xdp")
+int xdp_rss_hash(struct xdp_md *ctx)
+{
+	void *data_end = (void *)(long)ctx->data_end;
+	void *data = (void *)(long)ctx->data;
+	enum xdp_rss_hash_type rss_type = 0;
+	struct ethhdr *eth = data;
+	__u8 l4_proto = 0;
+	__u32 hash = 0;
+	__u32 key, val;
+	void *l4 = NULL;
+	__u32 *cnt;
+	int ret;
+
+	if ((void *)(eth + 1) > data_end)
+		return XDP_PASS;
+
+	if (eth->h_proto == bpf_htons(ETH_P_IP)) {
+		struct iphdr *iph = (void *)(eth + 1);
+
+		if ((void *)(iph + 1) > data_end)
+			return XDP_PASS;
+		l4_proto = iph->protocol;
+		l4 = (void *)(iph + 1);
+	} else if (eth->h_proto == bpf_htons(ETH_P_IPV6)) {
+		struct ipv6hdr *ip6h = (void *)(eth + 1);
+
+		if ((void *)(ip6h + 1) > data_end)
+			return XDP_PASS;
+		l4_proto = ip6h->nexthdr;
+		l4 = (void *)(ip6h + 1);
+	}
+
+	if (!l4)
+		return XDP_PASS;
+
+	/* Filter on the configured protocol (map_xdp_setup key XDP_PROTO).
+	 * When set, only process packets matching the requested L4 protocol.
+	 */
+	key = XDP_PROTO;
+	__s32 *proto_cfg = bpf_map_lookup_elem(&map_xdp_setup, &key);
+
+	if (proto_cfg && *proto_cfg != 0 && l4_proto != (__u8)*proto_cfg)
+		return XDP_PASS;
+
+	/* Filter on the configured port (map_xdp_setup key XDP_PORT).
+	 * Only applies to protocols with ports (UDP, TCP).
+	 */
+	key = XDP_PORT;
+	__s32 *port_cfg = bpf_map_lookup_elem(&map_xdp_setup, &key);
+
+	if (port_cfg && *port_cfg != 0) {
+		__u16 dest = get_dest_port(l4, data_end, l4_proto);
+
+		if (!dest || bpf_ntohs(dest) != (__u16)*port_cfg)
+			return XDP_PASS;
+	}
+
+	ret = bpf_xdp_metadata_rx_hash(ctx, &hash, &rss_type);
+	if (ret < 0) {
+		key = RSS_KEY_ERR_CNT;
+		cnt = bpf_map_lookup_elem(&map_rss, &key);
+		if (cnt)
+			__sync_fetch_and_add(cnt, 1);
+		return XDP_PASS;
+	}
+
+	key = RSS_KEY_HASH;
+	bpf_map_update_elem(&map_rss, &key, &hash, BPF_ANY);
+
+	key = RSS_KEY_TYPE;
+	val = (__u32)rss_type;
+	bpf_map_update_elem(&map_rss, &key, &val, BPF_ANY);
+
+	key = RSS_KEY_PKT_CNT;
+	cnt = bpf_map_lookup_elem(&map_rss, &key);
+	if (cnt)
+		__sync_fetch_and_add(cnt, 1);
+
+	return XDP_PASS;
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.43.0

Re: [PATCH net-next v4 6/6] selftests: drv-net: xdp: Add rss_hash metadata tests

[Jesper Dangaard Brouer]

On 13/03/2026 23.27, Chris J Arges wrote:
> diff --git a/tools/testing/selftests/net/lib/xdp_metadata.bpf.c b/tools/testing/selftests/net/lib/xdp_metadata.bpf.c
> new file mode 100644
> index 000000000000..f71f59215239
> --- /dev/null
> +++ b/tools/testing/selftests/net/lib/xdp_metadata.bpf.c
> @@ -0,0 +1,163 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <stddef.h>
> +#include <linux/bpf.h>
> +#include <linux/in.h>
> +#include <linux/if_ether.h>
> +#include <linux/ip.h>
> +#include <linux/ipv6.h>
> +#include <linux/udp.h>
> +#include <linux/tcp.h>
> +#include <bpf/bpf_endian.h>
> +#include <bpf/bpf_helpers.h>
> +
> +enum {
> +	XDP_PORT = 1,
> +	XDP_PROTO = 4,
> +} xdp_map_setup_keys;
> +
> +struct {
> +	__uint(type, BPF_MAP_TYPE_ARRAY);
> +	__uint(max_entries, 5);
> +	__type(key, __u32);
> +	__type(value, __s32);
> +} map_xdp_setup SEC(".maps");
> +
> +/* RSS hash results: key 0 = hash, key 1 = hash type,
> + * key 2 = packet count, key 3 = error count.
> + */
> +enum {
> +	RSS_KEY_HASH = 0,
> +	RSS_KEY_TYPE = 1,
> +	RSS_KEY_PKT_CNT = 2,
> +	RSS_KEY_ERR_CNT = 3,
> +};
> +
> +struct {
> +	__uint(type, BPF_MAP_TYPE_ARRAY);
> +	__type(key, __u32);
> +	__type(value, __u32);
> +	__uint(max_entries, 4);
> +} map_rss SEC(".maps");
> +
> +/* Mirror of enum xdp_rss_hash_type from include/net/xdp.h.
> + * Needed because the enum is not part of UAPI headers.

It is on purpose that enum is not part of UAPI headers, because BPF
progs (like this) are suppose to handle this via CO-RE.

Asking CO-RE experts (e.g. Cc Andrii), will below enum xdp_rss_hash_type
usage automatically get relocated by libbpf, based on running kernel?
(or do we need some explicit bpf_core_ calls?)

> + */
> +enum xdp_rss_hash_type {
> +	XDP_RSS_L3_IPV4 = 1U << 0,
> +	XDP_RSS_L3_IPV6 = 1U << 1,
> +	XDP_RSS_L3_DYNHDR = 1U << 2,
> +	XDP_RSS_L4 = 1U << 3,
> +	XDP_RSS_L4_TCP = 1U << 4,
> +	XDP_RSS_L4_UDP = 1U << 5,
> +	XDP_RSS_L4_SCTP = 1U << 6,
> +	XDP_RSS_L4_IPSEC = 1U << 7,
> +	XDP_RSS_L4_ICMP = 1U << 8,
> +};

--Jesper