The generic XDP tests in ping.py only cover XDP_PASS. Add a test that
redirects all packets to a cpumap with an xdp.frags program. It runs
the same ping and TCP checks as the other tests.

xdp_cpumap.bpf.c is a new program. It redirects every packet to entry 0
of a cpumap. It is not added to xdp_dummy.bpf.c. test_xdp_offload loads
xdp_dummy.bpf.o in offload mode, which would fail on a cpumap.

The new test extends _set_xdp_generic_mb_on() with two optional
arguments. The first argument, prog, is the XDP program file name, with
default "xdp_dummy.bpf.o". The second argument, on_attach, is a
callback function, with default None. on_attach runs right after the
program is attached. The new test passes "xdp_cpumap.bpf.o" to prog and
a lambda that adds the cpumap entry to on_attach.

Without the previous patch, the new test fails on netdevsim because ping
gets no reply.

Signed-off-by: Tianyi Gao <tianyi@cloudflare.com>
---
 tools/testing/selftests/drivers/net/ping.py   | 27 ++++++++++++++++---
 .../selftests/net/lib/xdp_cpumap.bpf.c        | 19 +++++++++++++
 2 files changed, 43 insertions(+), 3 deletions(-)
 create mode 100644 tools/testing/selftests/net/lib/xdp_cpumap.bpf.c

diff --git a/tools/testing/selftests/drivers/net/ping.py b/tools/testing/selftests/drivers/net/ping.py
index da3623c5e8a9..a0de9a98d906 100755
--- a/tools/testing/selftests/drivers/net/ping.py
+++ b/tools/testing/selftests/drivers/net/ping.py
@@ -7,7 +7,7 @@ from lib.py import ksft_run, ksft_exit
 from lib.py import ksft_eq, KsftSkipEx, KsftFailEx
 from lib.py import EthtoolFamily, NetDrvEpEnv
 from lib.py import bkg, cmd, wait_port_listen, rand_port
-from lib.py import defer, ethtool, ip
+from lib.py import bpf_map_set, defer, ethtool, ip
 
 no_sleep=False
 
@@ -75,16 +75,23 @@ def _set_xdp_generic_sb_on(cfg) -> None:
     if no_sleep != True:
         time.sleep(10)
 
-def _set_xdp_generic_mb_on(cfg) -> None:
-    prog = cfg.net_lib_dir / "xdp_dummy.bpf.o"
+def _set_xdp_generic_mb_on(cfg, prog="xdp_dummy.bpf.o", on_attach=None) -> None:
+    prog = cfg.net_lib_dir / prog
     cmd(f"ip link set dev {cfg.remote_ifname} mtu 9000", shell=True, host=cfg.remote)
     defer(ip, f"link set dev {cfg.remote_ifname} mtu 1500", host=cfg.remote)
     ip("link set dev %s mtu 9000 xdpgeneric obj %s sec xdp.frags" % (cfg.ifname, prog))
     defer(ip, f"link set dev {cfg.ifname} mtu 1500 xdpgeneric off")
+    if on_attach:
+        on_attach()
 
     if no_sleep != True:
         time.sleep(10)
 
+def _set_xdp_generic_cpumap_mb_on(cfg) -> None:
+    cfg.require_cmd("bpftool")
+    _set_xdp_generic_mb_on(cfg, "xdp_cpumap.bpf.o",
+                           on_attach=lambda: bpf_map_set("map_cpumap", 0, 2048))
+
 def _set_xdp_native_sb_on(cfg) -> None:
     prog = cfg.net_lib_dir / "xdp_dummy.bpf.o"
     cmd(f"ip link set dev {cfg.remote_ifname} mtu 1500", shell=True, host=cfg.remote)
@@ -192,6 +199,19 @@ def test_xdp_generic_mb(cfg, netnl) -> None:
     _test_v6(cfg)
     _test_tcp(cfg)
 
+def test_xdp_generic_cpumap_mb(cfg, netnl) -> None:
+    """Redirect all packets to a cpumap from a generic xdp.frags program."""
+    _schedule_checksum_reset(cfg, netnl)
+    _set_xdp_generic_cpumap_mb_on(cfg)
+    _set_offload_checksum(cfg, netnl, "off")
+    _test_v4(cfg)
+    _test_v6(cfg)
+    _test_tcp(cfg)
+    _set_offload_checksum(cfg, netnl, "on")
+    _test_v4(cfg)
+    _test_v6(cfg)
+    _test_tcp(cfg)
+
 def test_xdp_native_sb(cfg, netnl) -> None:
     _schedule_checksum_reset(cfg, netnl)
     _set_xdp_native_sb_on(cfg)
@@ -230,6 +250,7 @@ def main() -> None:
                   test_default_v6,
                   test_xdp_generic_sb,
                   test_xdp_generic_mb,
+                  test_xdp_generic_cpumap_mb,
                   test_xdp_native_sb,
                   test_xdp_native_mb,
                   test_xdp_offload],
diff --git a/tools/testing/selftests/net/lib/xdp_cpumap.bpf.c b/tools/testing/selftests/net/lib/xdp_cpumap.bpf.c
new file mode 100644
index 000000000000..150352343114
--- /dev/null
+++ b/tools/testing/selftests/net/lib/xdp_cpumap.bpf.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+struct {
+	__uint(type, BPF_MAP_TYPE_CPUMAP);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, __u32);
+} map_cpumap SEC(".maps");
+
+SEC("xdp.frags")
+int xdp_cpumap_prog_frags(struct xdp_md *ctx)
+{
+	return bpf_redirect_map(&map_cpumap, 0, XDP_DROP);
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.55.0