Message-ID: <8b37460c-8812-4427-ad54-2bab02058413@collabora.com>
Date: Sat, 12 Jul 2025 14:25:58 +0500
From: Muhammad Usama Anjum <usama.anjum@...labora.com>
To: Mohsin Bashir <mohsin.bashr@...il.com>, netdev@...r.kernel.org
Cc: kuba@...nel.org, andrew+netdev@...n.ch, davem@...emloft.net,
 edumazet@...gle.com, pabeni@...hat.com, shuah@...nel.org, horms@...nel.org,
 cratiu@...dia.com, noren@...dia.com, cjubran@...dia.com, mbloch@...dia.com,
 jdamato@...tly.com, gal@...dia.com, sdf@...ichev.me, ast@...nel.org,
 daniel@...earbox.net, hawk@...nel.org, john.fastabend@...il.com,
 bpf@...r.kernel.org, linux-kselftest@...r.kernel.org,
 usama.anjum@...labora.com
Subject: Re: [PATCH net-next V3 1/4] selftests: drv-net: Test XDP_PASS/DROP
 support

On 7/12/25 5:26 AM, Mohsin Bashir wrote:
> Test XDP_PASS/DROP in single buffer and multi buffer mode when
> XDP native support is available.
> 
> ./drivers/net/xdp.py
> TAP version 13
> 1..6
> ok 1 xdp.test_xdp_native_pass_sb
> ok 2 xdp.test_xdp_native_pass_mb
> ok 3 xdp.test_xdp_native_drop_sb
> ok 4 xdp.test_xdp_native_drop_mb
n exit a summary of passed and failed tests should be printed. Probably
a exit api call is missing?
# Totals: pass:4 fail:0 xfail:0 xpass:0 skip:0 error:0

> 
> Signed-off-by: Jakub Kicinski <kuba@...nel.org>
> Signed-off-by: Mohsin Bashir <mohsin.bashr@...il.com>
> ---
>  tools/testing/selftests/drivers/net/Makefile  |   1 +
>  tools/testing/selftests/drivers/net/xdp.py    | 303 ++++++++++++++++++
>  .../selftests/net/lib/xdp_native.bpf.c        | 158 +++++++++
>  3 files changed, 462 insertions(+)
>  create mode 100755 tools/testing/selftests/drivers/net/xdp.py
>  create mode 100644 tools/testing/selftests/net/lib/xdp_native.bpf.c
> 
> diff --git a/tools/testing/selftests/drivers/net/Makefile b/tools/testing/selftests/drivers/net/Makefile
> index bd309b2d3909..2ba7ae2bfe11 100644
> --- a/tools/testing/selftests/drivers/net/Makefile
> +++ b/tools/testing/selftests/drivers/net/Makefile
> @@ -21,6 +21,7 @@ TEST_PROGS := \
>  	stats.py \
>  	shaper.py \
>  	hds.py \
> +	xdp.py \
>  # end of TEST_PROGS
>  
>  include ../../lib.mk
> diff --git a/tools/testing/selftests/drivers/net/xdp.py b/tools/testing/selftests/drivers/net/xdp.py
> new file mode 100755
> index 000000000000..79a8156ed416
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/net/xdp.py
> @@ -0,0 +1,303 @@
> +#!/usr/bin/env python3
> +# SPDX-License-Identifier: GPL-2.0
> +
> +"""
> +This file contains tests to verify native XDP support in network drivers.
> +The tests utilize the BPF program `xdp_native.bpf.o` from the `selftests.net.lib`
> +directory, with each test focusing on a specific aspect of XDP functionality.
> +"""
> +import random
> +import string
> +from dataclasses import dataclass
> +from enum import Enum
> +
> +from lib.py import ksft_run, ksft_exit, ksft_eq, ksft_ne
Not related, but we have 2 ksft.py libraries currently:
tools/testing/selftests/kselftest/ksft.py
tools/testing/selftests/net/lib/py/ksft.py


> +from lib.py import KsftFailEx, NetDrvEpEnv
> +from lib.py import bkg, cmd, rand_port
> +from lib.py import ip, bpftool, defer
> +
> +
> +class TestConfig(Enum):
> +    """Enum for XDP configuration options."""
> +    MODE = 0  # Configures the BPF program for a specific test
> +    PORT = 1  # Port configuration to communicate with the remote host
> +
> +
> +class XDPAction(Enum):
> +    """Enum for XDP actions."""
> +    PASS = 0  # Pass the packet up to the stack
> +    DROP = 1  # Drop the packet
> +
> +
> +class XDPStats(Enum):
> +    """Enum for XDP statistics."""
> +    RX = 0    # Count of valid packets received for testing
> +    PASS = 1  # Count of packets passed up to the stack
> +    DROP = 2  # Count of packets dropped
> +
> +
> +@...aclass
> +class BPFProgInfo:
> +    """Data class to store information about a BPF program."""
> +    name: str               # Name of the BPF program
> +    file: str               # BPF program object file
> +    xdp_sec: str = "xdp"    # XDP section name (e.g., "xdp" or "xdp.frags")
> +    mtu: int = 1500         # Maximum Transmission Unit, default is 1500
> +
> +
> +def _exchg_udp(cfg, port, test_string):
> +    """
> +    Exchanges UDP packets between a local and remote host using the socat tool.
> +
> +    Args:
> +        cfg: Configuration object containing network settings.
> +        port: Port number to use for the UDP communication.
> +        test_string: String that the remote host will send.
> +
> +    Returns:
> +        The string received by the test host.
> +    """
> +    cfg.require_cmd("socat", remote=True)
> +
> +    rx_udp_cmd = f"socat -{cfg.addr_ipver} -T 2 -u UDP-RECV:{port},reuseport STDOUT"
> +    tx_udp_cmd = f"echo {test_string} | socat -t 2 -u STDIN UDP:{cfg.baddr}:{port}"
> +
> +    with bkg(rx_udp_cmd, exit_wait=True) as nc:
> +        cmd(tx_udp_cmd, host=cfg.remote, shell=True)
> +
> +    return nc.stdout.strip()
> +
> +
> +def _test_udp(cfg, port, size=256):
> +    """
> +    Tests UDP packet exchange between a local and remote host.
> +
> +    Args:
> +        cfg: Configuration object containing network settings.
> +        port: Port number to use for the UDP communication.
> +        size: The length of the test string to be exchanged, default is 256 characters.
> +
> +    Returns:
> +        bool: True if the received string matches the sent string, False otherwise.
> +    """
> +    test_str = "".join(random.choice(string.ascii_lowercase) for _ in range(size))
> +    recvd_str = _exchg_udp(cfg, port, test_str)
> +
> +    return recvd_str == test_str
> +
> +
> +def _load_xdp_prog(cfg, bpf_info):
> +    """
> +    Loads an XDP program onto a network interface.
> +
> +    Args:
> +        cfg: Configuration object containing network settings.
> +        bpf_info: BPFProgInfo object containing information about the BPF program.
> +
> +    Returns:
> +        dict: A dictionary containing the XDP program ID, name, and associated map IDs.
> +    """
> +    abs_path = cfg.net_lib_dir / bpf_info.file
> +    prog_info = {}
> +
> +    cmd(f"ip link set dev {cfg.remote_ifname} mtu {bpf_info.mtu}", shell=True, host=cfg.remote)
> +    defer(ip, f"link set dev {cfg.remote_ifname} mtu 1500", host=cfg.remote)
> +
> +    cmd(
> +    f"ip link set dev {cfg.ifname} mtu {bpf_info.mtu} xdp obj {abs_path} sec {bpf_info.xdp_sec}",
> +    shell=True
> +    )
> +    defer(ip, f"link set dev {cfg.ifname} mtu 1500 xdp off")
> +
> +    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
> +
> +    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.
> +
> +    Args:
> +        xdp_map_id: The ID of the XDP map from which to retrieve statistics.
> +
> +    Returns:
> +        A dictionary containing formatted packet statistics for various XDP actions.
> +        The keys are based on the XDPStats Enum values.
> +
> +    Raises:
> +        KsftFailEx: If the stats retrieval fails.
> +    """
> +    stats_dump = bpftool(f"map dump id {xdp_map_id}", json=True)
> +    if not stats_dump:
> +        raise KsftFailEx(f"Failed to get stats for map {xdp_map_id}")
> +
> +    stats_formatted = {}
> +    for key in range(0, 4):
> +        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
> +
> +    return stats_formatted
> +
> +
> +def _test_pass(cfg, bpf_info, msg_sz):
> +    """
> +    Tests the XDP_PASS action by exchanging UDP packets.
> +
> +    Args:
> +        cfg: Configuration object containing network settings.
> +        bpf_info: BPFProgInfo object containing information about the BPF program.
> +        msg_sz: Size of the test message to send.
> +    """
> +
> +    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)
> +
> +    ksft_eq(_test_udp(cfg, port, msg_sz), True, "UDP packet exchange failed")
> +    stats = _get_stats(prog_info["maps"]["map_xdp_stats"])
> +
> +    ksft_ne(stats[XDPStats.RX.value], 0, "RX stats should not be zero")
> +    ksft_eq(stats[XDPStats.RX.value], stats[XDPStats.PASS.value], "RX and PASS stats mismatch")
> +
> +
> +def test_xdp_native_pass_sb(cfg):
> +    """
> +    Tests the XDP_PASS action for single buffer case.
> +
> +    Args:
> +        cfg: Configuration object containing network settings.
> +    """
> +    bpf_info = BPFProgInfo("xdp_prog", "xdp_native.bpf.o", "xdp", 1500)
> +
> +    _test_pass(cfg, bpf_info, 256)
> +
> +
> +def test_xdp_native_pass_mb(cfg):
> +    """
> +    Tests the XDP_PASS action for a multi-buff size.
> +
> +    Args:
> +        cfg: Configuration object containing network settings.
> +    """
> +    bpf_info = BPFProgInfo("xdp_prog_frags", "xdp_native.bpf.o", "xdp.frags", 9000)
> +
> +    _test_pass(cfg, bpf_info, 8000)
> +
> +
> +def _test_drop(cfg, bpf_info, msg_sz):
> +    """
> +    Tests the XDP_DROP action by exchanging UDP packets.
> +
> +    Args:
> +        cfg: Configuration object containing network settings.
> +        bpf_info: BPFProgInfo object containing information about the BPF program.
> +        msg_sz: Size of the test message to send.
> +    """
> +
> +    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)
> +
> +    ksft_eq(_test_udp(cfg, port, msg_sz), False, "UDP packet exchange should fail")
> +    stats = _get_stats(prog_info["maps"]["map_xdp_stats"])
> +
> +    ksft_ne(stats[XDPStats.RX.value], 0, "RX stats should be zero")
> +    ksft_eq(stats[XDPStats.RX.value], stats[XDPStats.DROP.value], "RX and DROP stats mismatch")
> +
> +
> +def test_xdp_native_drop_sb(cfg):
> +    """
> +    Tests the XDP_DROP action for a signle-buff case.
> +
> +    Args:
> +        cfg: Configuration object containing network settings.
> +    """
> +    bpf_info = BPFProgInfo("xdp_prog", "xdp_native.bpf.o", "xdp", 1500)
> +
> +    _test_drop(cfg, bpf_info, 256)
> +
> +
> +def test_xdp_native_drop_mb(cfg):
> +    """
> +    Tests the XDP_DROP action for a multi-buff case.
> +
> +    Args:
> +        cfg: Configuration object containing network settings.
> +    """
> +    bpf_info = BPFProgInfo("xdp_prog_frags", "xdp_native.bpf.o", "xdp.frags", 9000)
> +
> +    _test_drop(cfg, bpf_info, 8000)
> +
> +
> +def main():
> +    """
> +    Main function to execute the XDP tests.
> +
> +    This function runs a series of tests to validate the XDP support for
> +    both the single and multi-buffer. It uses the NetDrvEpEnv context
> +    manager to manage the network driver environment and the ksft_run
> +    function to execute the tests.
> +    """
> +    with NetDrvEpEnv(__file__) as cfg:
> +        ksft_run(
> +            [
> +                test_xdp_native_pass_sb,
> +                test_xdp_native_pass_mb,
> +                test_xdp_native_drop_sb,
> +                test_xdp_native_drop_mb,
> +            ],
> +            args=(cfg,))
> +    ksft_exit()
> +
> +
> +if __name__ == "__main__":
> +    main()
> diff --git a/tools/testing/selftests/net/lib/xdp_native.bpf.c b/tools/testing/selftests/net/lib/xdp_native.bpf.c
> new file mode 100644
> index 000000000000..90b34b2a4fef
> --- /dev/null
> +++ b/tools/testing/selftests/net/lib/xdp_native.bpf.c
> @@ -0,0 +1,158 @@
> +// 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 <bpf/bpf_endian.h>
> +#include <bpf/bpf_helpers.h>
> +
> +enum {
> +	XDP_MODE = 0,
> +	XDP_PORT = 1,
> +} xdp_map_setup_keys;
> +
> +enum {
> +	XDP_MODE_PASS = 0,
> +	XDP_MODE_DROP = 1,
> +} xdp_map_modes;
> +
> +enum {
> +	STATS_RX = 0,
> +	STATS_PASS = 1,
> +	STATS_DROP = 2,
> +} xdp_stats;
> +
> +struct {
> +	__uint(type, BPF_MAP_TYPE_ARRAY);
> +	__uint(max_entries, 2);
> +	__type(key, __u32);
> +	__type(value, __s32);
> +} map_xdp_setup SEC(".maps");
> +
> +struct {
> +	__uint(type, BPF_MAP_TYPE_ARRAY);
> +	__uint(max_entries, 4);
> +	__type(key, __u32);
> +	__type(value, __u64);
> +} map_xdp_stats SEC(".maps");
> +
> +static void record_stats(struct xdp_md *ctx, __u32 stat_type)
> +{
> +	__u64 *count;
> +
> +	count = bpf_map_lookup_elem(&map_xdp_stats, &stat_type);
> +
> +	if (count)
> +		__sync_fetch_and_add(count, 1);
> +}
> +
> +static struct udphdr *filter_udphdr(struct xdp_md *ctx, __u16 port)
> +{
> +	void *data_end = (void *)(long)ctx->data_end;
> +	void *data = (void *)(long)ctx->data;
> +	struct udphdr *udph = NULL;
> +	struct ethhdr *eth = data;
> +
> +	if (data + sizeof(*eth) > data_end)
> +		return NULL;
> +
> +	if (eth->h_proto == bpf_htons(ETH_P_IP)) {
> +		struct iphdr *iph = data + sizeof(*eth);
> +
> +		if (iph + 1 > (struct iphdr *)data_end ||
> +		    iph->protocol != IPPROTO_UDP)
> +			return NULL;
> +
> +		udph = (void *)eth + sizeof(*iph) + sizeof(*eth);
> +	} else if (eth->h_proto  == bpf_htons(ETH_P_IPV6)) {
> +		struct ipv6hdr *ipv6h = data + sizeof(*eth);
> +
> +		if (ipv6h + 1 > (struct ipv6hdr *)data_end ||
> +		    ipv6h->nexthdr != IPPROTO_UDP)
> +			return NULL;
> +
> +		udph = (void *)eth + sizeof(*ipv6h) + sizeof(*eth);
> +	} else {
> +		return NULL;
> +	}
> +
> +	if (udph + 1 > (struct udphdr *)data_end)
> +		return NULL;
> +
> +	if (udph->dest != bpf_htons(port))
> +		return NULL;
> +
> +	record_stats(ctx, STATS_RX);
> +
> +	return udph;
> +}
> +
> +static int xdp_mode_pass(struct xdp_md *ctx, __u16 port)
> +{
> +	struct udphdr *udph = NULL;
> +
> +	udph = filter_udphdr(ctx, port);
> +	if (!udph)
> +		return XDP_PASS;
> +
> +	record_stats(ctx, STATS_PASS);
> +
> +	return XDP_PASS;
> +}
> +
> +static int xdp_mode_drop_handler(struct xdp_md *ctx, __u16 port)
> +{
> +	struct udphdr *udph = NULL;
> +
> +	udph = filter_udphdr(ctx, port);
> +	if (!udph)
> +		return XDP_PASS;
> +
> +	record_stats(ctx, STATS_DROP);
> +
> +	return XDP_DROP;
> +}
> +
> +static int xdp_prog_common(struct xdp_md *ctx)
> +{
> +	__u32 key, *port;
> +	__s32 *mode;
> +
> +	key = XDP_MODE;
> +	mode = bpf_map_lookup_elem(&map_xdp_setup, &key);
> +	if (!mode)
> +		return XDP_PASS;
> +
> +	key = XDP_PORT;
> +	port = bpf_map_lookup_elem(&map_xdp_setup, &key);
> +	if (!port)
> +		return XDP_PASS;
> +
> +	switch (*mode) {
> +	case XDP_MODE_PASS:
> +		return xdp_mode_pass(ctx, (__u16)(*port));
> +	case XDP_MODE_DROP:
> +		return xdp_mode_drop_handler(ctx, (__u16)(*port));
> +	}
> +
> +	/* Default action is to simple pass */
> +	return XDP_PASS;
> +}
> +
> +SEC("xdp")
> +int xdp_prog(struct xdp_md *ctx)
> +{
> +	return xdp_prog_common(ctx);
> +}
> +
> +SEC("xdp.frags")
> +int xdp_prog_frags(struct xdp_md *ctx)
> +{
> +	return xdp_prog_common(ctx);
> +}
> +
> +char _license[] SEC("license") = "GPL";

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