netdev - [PATCH RFC bpf-next 6/6] selftests/bpf: Add bpf_xdp_metadata_rx_checksum support to xdp_hw

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Message-Id: <20250920-xdp-meta-rxcksum-v1-6-35e76a8a84e7@kernel.org>
Date: Sat, 20 Sep 2025 14:20:32 +0200
From: Lorenzo Bianconi <lorenzo@...nel.org>
To: Donald Hunter <donald.hunter@...il.com>, 
 Jakub Kicinski <kuba@...nel.org>, "David S. Miller" <davem@...emloft.net>, 
 Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, 
 Simon Horman <horms@...nel.org>, Alexei Starovoitov <ast@...nel.org>, 
 Daniel Borkmann <daniel@...earbox.net>, 
 Jesper Dangaard Brouer <hawk@...nel.org>, 
 John Fastabend <john.fastabend@...il.com>, 
 Stanislav Fomichev <sdf@...ichev.me>, Andrew Lunn <andrew+netdev@...n.ch>, 
 Tony Nguyen <anthony.l.nguyen@...el.com>, 
 Przemek Kitszel <przemyslaw.kitszel@...el.com>, 
 Alexander Lobakin <aleksander.lobakin@...el.com>, 
 Andrii Nakryiko <andrii@...nel.org>, 
 Martin KaFai Lau <martin.lau@...ux.dev>, 
 Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>, 
 Yonghong Song <yonghong.song@...ux.dev>, KP Singh <kpsingh@...nel.org>, 
 Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>, 
 Shuah Khan <shuah@...nel.org>
Cc: netdev@...r.kernel.org, bpf@...r.kernel.org, 
 intel-wired-lan@...ts.osuosl.org, linux-kselftest@...r.kernel.org, 
 Lorenzo Bianconi <lorenzo@...nel.org>
Subject: [PATCH RFC bpf-next 6/6] selftests/bpf: Add
 bpf_xdp_metadata_rx_checksum support to xdp_hw_metadat prog

Introduce the capability to dump HW rx checksum in xdp_hw_metadat
program via bpf_xdp_metadata_rx_checksum() kfunc.

Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>
---
 .../testing/selftests/bpf/progs/xdp_hw_metadata.c  |  7 ++++++
 tools/testing/selftests/bpf/xdp_hw_metadata.c      | 27 ++++++++++++++++++++++
 tools/testing/selftests/bpf/xdp_metadata.h         | 10 +++++---
 3 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
index 330ece2eabdb454da2bb2cbd297d2b2dd6efddc0..dc62d572e3ac6e2ef173b330da515757ea543415 100644
--- a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
+++ b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
@@ -110,6 +110,13 @@ int rx(struct xdp_md *ctx)
 	else
 		meta->hint_valid |= XDP_META_FIELD_VLAN_TAG;

+	err = bpf_xdp_metadata_rx_checksum(ctx, &meta->ip_summed,
+					   &meta->cksum_meta);
+	if (err)
+		meta->rx_cksum_err = err;
+	else
+		meta->hint_valid |= XDP_META_FIELD_CHECKSUM;
+
 	__sync_add_and_fetch(&pkts_redir, 1);
 	return bpf_redirect_map(&xsk, ctx->rx_queue_index, XDP_PASS);
 }
diff --git a/tools/testing/selftests/bpf/xdp_hw_metadata.c b/tools/testing/selftests/bpf/xdp_hw_metadata.c
index 3d8de0d4c96a7afdf5f60b2fdff73c22b876ce54..5e38aa1b565735c2e55fcf2f7b9e672db1348233 100644
--- a/tools/testing/selftests/bpf/xdp_hw_metadata.c
+++ b/tools/testing/selftests/bpf/xdp_hw_metadata.c
@@ -219,6 +219,28 @@ static void print_vlan_tci(__u16 tag)
 	printf("PCP=%u, DEI=%d, VID=0x%X\n", pcp, dei, vlan_id);
 }

+static void print_rx_cksum(__u8 ip_summed, __u32 cksum_meta)
+{
+	const char *cksum = "CHECKSUM_NONE";
+
+	switch (ip_summed) {
+	case CHECKSUM_UNNECESSARY:
+		cksum = "CHECKSUM_UNNECESSARY";
+		break;
+	case CHECKSUM_COMPLETE:
+		cksum = "CHECKSUM_COMPLETE";
+		break;
+	case CHECKSUM_PARTIAL:
+		cksum = "CHECKSUM_PARTIAL";
+		break;
+	case CHECKSUM_NONE:
+	default:
+		break;
+	}
+
+	printf("rx-cksum: %s, csum_meta=0x%x\n", cksum, cksum_meta);
+}
+
 static void verify_xdp_metadata(void *data, clockid_t clock_id)
 {
 	struct xdp_meta *meta;
@@ -254,6 +276,11 @@ static void verify_xdp_metadata(void *data, clockid_t clock_id)
 		printf("No rx_vlan_tci or rx_vlan_proto, err=%d\n",
 		       meta->rx_vlan_tag_err);
 	}
+
+	if (meta->hint_valid & XDP_META_FIELD_CHECKSUM)
+		print_rx_cksum(meta->ip_summed, meta->cksum_meta);
+	else
+		printf("No rx_chsum, err=%d\n", meta->rx_cksum_err);
 }

 static void verify_skb_metadata(int fd)
diff --git a/tools/testing/selftests/bpf/xdp_metadata.h b/tools/testing/selftests/bpf/xdp_metadata.h
index f0ef17b328866206b1e63f7d751abeaa78e90932..0fd5e7172fe891275b3b1eb69c51a93a60ae353e 100644
--- a/tools/testing/selftests/bpf/xdp_metadata.h
+++ b/tools/testing/selftests/bpf/xdp_metadata.h
@@ -28,6 +28,7 @@ enum xdp_meta_field {
 	XDP_META_FIELD_TS	= BIT(0),
 	XDP_META_FIELD_RSS	= BIT(1),
 	XDP_META_FIELD_VLAN_TAG	= BIT(2),
+	XDP_META_FIELD_CHECKSUM = BIT(3),
 };

 #define CHECKSUM_NONE		0
@@ -53,9 +54,12 @@ struct xdp_meta {
 		};
 		__s32 rx_vlan_tag_err;
 	};
-	struct {
-		__u8 ip_summed;
-		__u32 cksum_meta;
+	union {
+		struct {
+			__u8 ip_summed;
+			__u32 cksum_meta;
+		};
+		__s32 rx_cksum_err;
 	};
 	enum xdp_meta_field hint_valid;
 };

-- 
2.51.0