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@kernel.org>

Author: LorenzoBianconi

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);
 }

tools/testing/selftests/bpf/xdp_hw_metadata.c

@@ -8,6 +8,7 @@
  * - Metadata verified:
  *   - rx_timestamp
  *   - rx_hash
+ *   - rx_checksum
  *
  * TX:
  * - UDP 9091 packets trigger TX reply
@@ -219,6 +220,28 @@ 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 XDP_CHECKSUM_UNNECESSARY:
+		cksum = "CHECKSUM_UNNECESSARY";
+		break;
+	case XDP_CHECKSUM_COMPLETE:
+		cksum = "CHECKSUM_COMPLETE";
+		break;
+	case XDP_CHECKSUM_PARTIAL:
+		cksum = "CHECKSUM_PARTIAL";
+		break;
+	case XDP_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 +277,11 @@ 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)

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 XDP_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;
 };