[PATCH net v2 2/2] selftests/bpf: cover AF_XDP multi-buffer TX software checksum

@@ -19,6 +19,8 @@
 #define RX_NAME "veRX"
 
 #define UDP_PAYLOAD_BYTES 4
+#define UDP_SPLIT_BYTES (sizeof(struct ethhdr) + sizeof(struct iphdr) + \
+			   sizeof(struct udphdr))
 
 #define UDP_SOURCE_PORT 1234
 #define AF_XDP_CONSUMER_PORT 8080

@@ -56,13 +58,13 @@ struct xsk {
 	struct xsk_socket *socket;
 };
 
-static int open_xsk(int ifindex, struct xsk *xsk)
+static int open_xsk(int ifindex, struct xsk *xsk, __u32 bind_flags)
 {
 	int mmap_flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE;
 	const struct xsk_socket_config socket_config = {
 		.rx_size = XSK_RING_PROD__DEFAULT_NUM_DESCS,
 		.tx_size = XSK_RING_PROD__DEFAULT_NUM_DESCS,
-		.bind_flags = XDP_COPY,
+		.bind_flags = bind_flags,
 	};
 	const struct xsk_umem_config umem_config = {
 		.fill_size = XSK_RING_PROD__DEFAULT_NUM_DESCS,

@@ -133,36 +135,36 @@ static void close_xsk(struct xsk *xsk)
 	munmap(xsk->umem_area, UMEM_SIZE);
 }
 
-static int generate_packet(struct xsk *xsk, __u16 dst_port)
+static int generate_packet(struct xsk *xsk, __u16 dst_port, u16 split_len)
 {
 	struct xsk_tx_metadata *meta;
 	struct xdp_desc *tx_desc;
 	struct udphdr *udph;
 	struct ethhdr *eth;
 	struct iphdr *iph;
+	u16 pkt_len;
+	u32 num, addr;
 	void *data;
 	__u32 idx;
+	u8 pkt[256];
 	int ret;
 
-	ret = xsk_ring_prod__reserve(&xsk->tx, 1, &idx);
-	if (!ASSERT_EQ(ret, 1, "xsk_ring_prod__reserve"))
+	pkt_len = sizeof(*eth) + sizeof(*iph) + sizeof(*udph) + UDP_PAYLOAD_BYTES;
+	if (!ASSERT_LT(split_len, pkt_len, "split_len"))
 		return -1;
 
-	tx_desc = xsk_ring_prod__tx_desc(&xsk->tx, idx);
-	tx_desc->addr = idx % (UMEM_NUM / 2) * UMEM_FRAME_SIZE + sizeof(struct xsk_tx_metadata);
-	printf("%p: tx_desc[%u]->addr=%llx\n", xsk, idx, tx_desc->addr);
-	data = xsk_umem__get_data(xsk->umem_area, tx_desc->addr);
-
-	meta = data - sizeof(struct xsk_tx_metadata);
-	memset(meta, 0, sizeof(*meta));
-	meta->flags = XDP_TXMD_FLAGS_TIMESTAMP;
+	num = split_len ? 2 : 1;
+	ret = xsk_ring_prod__reserve(&xsk->tx, num, &idx);
+	if (!ASSERT_EQ(ret, num, "xsk_ring_prod__reserve"))
+		return -1;
 
-	eth = data;
+	memset(pkt, 0, sizeof(pkt));
+	eth = (void *)pkt;
 	iph = (void *)(eth + 1);
 	udph = (void *)(iph + 1);
 
-	memcpy(eth->h_dest, "\x00\x00\x00\x00\x00\x02", ETH_ALEN);
-	memcpy(eth->h_source, "\x00\x00\x00\x00\x00\x01", ETH_ALEN);
+	memcpy(eth->h_dest, RX_MAC, ETH_ALEN);
+	memcpy(eth->h_source, TX_MAC, ETH_ALEN);
 	eth->h_proto = htons(ETH_P_IP);
 
 	iph->version = 0x4;

@@ -180,18 +182,38 @@ static int generate_packet(struct xsk *xsk, __u16 dst_port)
 	udph->source = htons(UDP_SOURCE_PORT);
 	udph->dest = htons(dst_port);
 	udph->len = htons(sizeof(*udph) + UDP_PAYLOAD_BYTES);
+	memset(udph + 1, 0xAA, UDP_PAYLOAD_BYTES);
 	udph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
 					 ntohs(udph->len), IPPROTO_UDP, 0);
 
-	memset(udph + 1, 0xAA, UDP_PAYLOAD_BYTES);
+	addr = idx % (UMEM_NUM / 2) * UMEM_FRAME_SIZE;
+	tx_desc = xsk_ring_prod__tx_desc(&xsk->tx, idx);
+	tx_desc->addr = addr + sizeof(*meta);
+	tx_desc->len = split_len ? split_len : pkt_len;
+	tx_desc->options = XDP_TX_METADATA;
+	printf("%p: tx_desc[%u]->addr=%llx\n", xsk, idx, tx_desc->addr);
+	data = xsk_umem__get_data(xsk->umem_area, tx_desc->addr);
+	memcpy(data, pkt, tx_desc->len);
 
-	meta->flags |= XDP_TXMD_FLAGS_CHECKSUM;
+	meta = data - sizeof(*meta);
+	memset(meta, 0, sizeof(*meta));
+	meta->flags = XDP_TXMD_FLAGS_TIMESTAMP | XDP_TXMD_FLAGS_CHECKSUM;
 	meta->request.csum_start = sizeof(*eth) + sizeof(*iph);
 	meta->request.csum_offset = offsetof(struct udphdr, check);
 
-	tx_desc->len = sizeof(*eth) + sizeof(*iph) + sizeof(*udph) + UDP_PAYLOAD_BYTES;
-	tx_desc->options |= XDP_TX_METADATA;
-	xsk_ring_prod__submit(&xsk->tx, 1);
+	if (split_len) {
+		u32 addr2 = (idx + 1) % (UMEM_NUM / 2) * UMEM_FRAME_SIZE;
+
+		tx_desc->options |= XDP_PKT_CONTD;
+		tx_desc = xsk_ring_prod__tx_desc(&xsk->tx, idx + 1);
+		tx_desc->addr = addr2 + sizeof(*meta);
+		tx_desc->len = pkt_len - split_len;
+		tx_desc->options = 0;
+		data = xsk_umem__get_data(xsk->umem_area, tx_desc->addr);
+		memcpy(data, pkt + split_len, tx_desc->len);
+	}
+
+	xsk_ring_prod__submit(&xsk->tx, num);
 
 	ret = sendto(xsk_socket__fd(xsk->socket), NULL, 0, MSG_DONTWAIT, NULL, 0);
 	if (!ASSERT_GE(ret, 0, "sendto"))

@@ -224,24 +246,26 @@ static int generate_packet_inet(void)
 	return err;
 }
 
-static void complete_tx(struct xsk *xsk)
+static void complete_tx(struct xsk *xsk, u32 num)
 {
 	struct xsk_tx_metadata *meta;
 	__u64 addr;
 	void *data;
-	__u32 idx;
-
-	if (ASSERT_EQ(xsk_ring_cons__peek(&xsk->comp, 1, &idx), 1, "xsk_ring_cons__peek")) {
-		addr = *xsk_ring_cons__comp_addr(&xsk->comp, idx);
-
-		printf("%p: complete tx idx=%u addr=%llx\n", xsk, idx, addr);
-
-		data = xsk_umem__get_data(xsk->umem_area, addr);
-		meta = data - sizeof(struct xsk_tx_metadata);
-
-		ASSERT_NEQ(meta->completion.tx_timestamp, 0, "tx_timestamp");
-
-		xsk_ring_cons__release(&xsk->comp, 1);
+	__u32 idx, i;
+
+	if (ASSERT_EQ(xsk_ring_cons__peek(&xsk->comp, num, &idx), num,
+		      "xsk_ring_cons__peek")) {
+		for (i = 0; i < num; i++) {
+			addr = *xsk_ring_cons__comp_addr(&xsk->comp, idx + i);
+			printf("%p: complete tx idx=%u addr=%llx\n", xsk, idx + i, addr);
+
+			if (i == 0) {
+				data = xsk_umem__get_data(xsk->umem_area, addr);
+				meta = data - sizeof(*meta);
+				ASSERT_NEQ(meta->completion.tx_timestamp, 0, "tx_timestamp");
+			}
+		}
+		xsk_ring_cons__release(&xsk->comp, num);
 	}
 }
 

@@ -398,7 +422,7 @@ void test_xdp_metadata(void)
 
 	/* Setup separate AF_XDP for RX interface. */
 
-	ret = open_xsk(rx_ifindex, &rx_xsk);
+	ret = open_xsk(rx_ifindex, &rx_xsk, XDP_COPY);
 	if (!ASSERT_OK(ret, "open_xsk(RX_NAME)"))
 		goto out;
 

@@ -462,11 +486,11 @@ void test_xdp_metadata(void)
 
 	/* Setup separate AF_XDP for TX interface nad send packet to the RX socket. */
 	tx_ifindex = if_nametoindex(TX_NAME);
-	ret = open_xsk(tx_ifindex, &tx_xsk);
+	ret = open_xsk(tx_ifindex, &tx_xsk, XDP_COPY | XDP_USE_SG);
 	if (!ASSERT_OK(ret, "open_xsk(TX_NAME)"))
 		goto out;
 
-	if (!ASSERT_GE(generate_packet(&tx_xsk, AF_XDP_CONSUMER_PORT), 0,
+	if (!ASSERT_GE(generate_packet(&tx_xsk, AF_XDP_CONSUMER_PORT, 0), 0,
 		       "generate AF_XDP_CONSUMER_PORT"))
 		goto out;
 

@@ -482,7 +506,29 @@ void test_xdp_metadata(void)
 	switch_ns_to_tx(&tok);
 	if (!ASSERT_OK_PTR(tok, "setns tx"))
 		goto out;
-	complete_tx(&tx_xsk);
+	complete_tx(&tx_xsk, 1);
+
+	/* Exercise software checksumming of a packet spread over multiple
+	 * TX descriptors. The checksum is only computed once the skb is
+	 * complete, so both fragments must be accounted for.
+	 */
+	if (!ASSERT_GE(generate_packet(&tx_xsk, AF_XDP_CONSUMER_PORT,
+				       UDP_SPLIT_BYTES), 0,
+		       "generate multi-buffer AF_XDP packet"))
+		goto out;
+
+	switch_ns_to_rx(&tok);
+	if (!ASSERT_OK_PTR(tok, "setns rx"))
+		goto out;
+
+	if (!ASSERT_GE(verify_xsk_metadata(&rx_xsk, true), 0,
+		       "verify multi-buffer xsk metadata"))
+		goto out;
+
+	switch_ns_to_tx(&tok);
+	if (!ASSERT_OK_PTR(tok, "setns tx"))
+		goto out;
+	complete_tx(&tx_xsk, 2);
 
 	/* Now check metadata of packet, generated with network stack */
 	if (!ASSERT_GE(generate_packet_inet(), 0, "generate UDP packet"))

@@ -518,7 +564,7 @@ void test_xdp_metadata(void)
 		goto out;
 
 	/* Send packet to trigger . */
-	if (!ASSERT_GE(generate_packet(&tx_xsk, AF_XDP_CONSUMER_PORT), 0,
+	if (!ASSERT_GE(generate_packet(&tx_xsk, AF_XDP_CONSUMER_PORT, 0), 0,
 		       "generate freplace packet"))
 		goto out;