[PATCH v5 2/2] examples/l3fwd: relax RX Offload with option

[Trevor Tao <taozj888@163.com>]

Now the port Rx offload mode is set to RTE_ETH_RX_OFFLOAD_CHECKSUM
by default, but some hw and/or virtual interface does not support
the offload mode presupposed, e.g., some virtio interfaces in
the cloud may only partly support RTE_ETH_RX_OFFLOAD_UDP_CKSUM/
RTE_ETH_RX_OFFLOAD_TCP_CKSUM,
but not RTE_ETH_RX_OFFLOAD_IPV4_CKSUM, and the error msg here:

Ethdev port_id=0 requested Rx offloads 0xe does not match Rx offloads
capabilities 0x201d in rte_eth_dev_configure()

So to enable the l3fwd running in that environment, the Rx mode requirement
can be relaxed to reflect the hardware feature reality here with an option
relax_rx_offload, and the l3fwd can run smoothly then.
A warning msg would be provided to user in case it happens here.

On the other side, enabling the software cksum check in case missing the
hw support.

The relax action for rx cksum offload is just enabled when
relax_rx_offload is true which is false by default.

Signed-off-by: Trevor Tao <taozj888@163.com>
---
 examples/l3fwd/l3fwd.h     | 12 ++++++++++--
 examples/l3fwd/l3fwd_em.h  |  2 +-
 examples/l3fwd/l3fwd_lpm.h |  2 +-
 examples/l3fwd/main.c      | 24 ++++++++++++++++++++++++
 4 files changed, 36 insertions(+), 4 deletions(-)

diff --git a/examples/l3fwd/l3fwd.h b/examples/l3fwd/l3fwd.h
index b55855c932..e7ae0e5834 100644
--- a/examples/l3fwd/l3fwd.h
+++ b/examples/l3fwd/l3fwd.h
@@ -159,7 +159,7 @@ send_single_packet(struct lcore_conf *qconf,
 
 #ifdef DO_RFC_1812_CHECKS
 static inline int
-is_valid_ipv4_pkt(struct rte_ipv4_hdr *pkt, uint32_t link_len)
+is_valid_ipv4_pkt(struct rte_ipv4_hdr *pkt, uint32_t link_len, uint64_t ol_flags)
 {
 	/* From http://www.rfc-editor.org/rfc/rfc1812.txt section 5.2.2 */
 	/*
@@ -170,7 +170,15 @@ is_valid_ipv4_pkt(struct rte_ipv4_hdr *pkt, uint32_t link_len)
 		return -1;
 
 	/* 2. The IP checksum must be correct. */
-	/* this is checked in H/W */
+	/* if this is not checked in H/W, check it. */
+	if ((ol_flags & RTE_MBUF_F_RX_IP_CKSUM_MASK) == RTE_MBUF_F_RX_IP_CKSUM_NONE) {
+		uint16_t actual_cksum, expected_cksum;
+		actual_cksum = pkt->hdr_checksum;
+		pkt->hdr_checksum = 0;
+		expected_cksum = rte_ipv4_cksum(pkt);
+		if (actual_cksum != expected_cksum)
+			return -2;
+	}
 
 	/*
 	 * 3. The IP version number must be 4. If the version number is not 4
diff --git a/examples/l3fwd/l3fwd_em.h b/examples/l3fwd/l3fwd_em.h
index 7d051fc076..1fee2e2e6c 100644
--- a/examples/l3fwd/l3fwd_em.h
+++ b/examples/l3fwd/l3fwd_em.h
@@ -20,7 +20,7 @@ l3fwd_em_handle_ipv4(struct rte_mbuf *m, uint16_t portid,
 
 #ifdef DO_RFC_1812_CHECKS
 	/* Check to make sure the packet is valid (RFC1812) */
-	if (is_valid_ipv4_pkt(ipv4_hdr, m->pkt_len) < 0) {
+	if (is_valid_ipv4_pkt(ipv4_hdr, m->pkt_len, m->ol_flags) < 0) {
 		rte_pktmbuf_free(m);
 		return BAD_PORT;
 	}
diff --git a/examples/l3fwd/l3fwd_lpm.h b/examples/l3fwd/l3fwd_lpm.h
index c61b969584..4ee61e8d88 100644
--- a/examples/l3fwd/l3fwd_lpm.h
+++ b/examples/l3fwd/l3fwd_lpm.h
@@ -22,7 +22,7 @@ l3fwd_lpm_simple_forward(struct rte_mbuf *m, uint16_t portid,
 
 #ifdef DO_RFC_1812_CHECKS
 		/* Check to make sure the packet is valid (RFC1812) */
-		if (is_valid_ipv4_pkt(ipv4_hdr, m->pkt_len) < 0) {
+		if (is_valid_ipv4_pkt(ipv4_hdr, m->pkt_len, m->ol_flags) < 0) {
 			rte_pktmbuf_free(m);
 			return;
 		}
diff --git a/examples/l3fwd/main.c b/examples/l3fwd/main.c
index b42365ef1b..851e7e68f9 100644
--- a/examples/l3fwd/main.c
+++ b/examples/l3fwd/main.c
@@ -74,6 +74,8 @@ static int numa_on = 1; /**< NUMA is enabled by default. */
 static int parse_ptype; /**< Parse packet type using rx callback, and */
 			/**< disabled by default */
 static int disable_rss; /**< Disable the RX RSS mode */
+static int relax_rx_offload; /**< Relax RX offload mode, and */
+			     /**< disabled by default */
 static int per_port_pool; /**< Use separate buffer pools per port; disabled */
 			  /**< by default */
 
@@ -680,6 +682,7 @@ static const char short_options[] =
 #define CMD_LINE_OPT_HASH_ENTRY_NUM "hash-entry-num"
 #define CMD_LINE_OPT_PARSE_PTYPE "parse-ptype"
 #define CMD_LINE_OPT_DISABLE_RSS "disable-rss"
+#define CMD_LINE_OPT_RELAX_RX_OFFLOAD "relax-rx-offload"
 #define CMD_LINE_OPT_PER_PORT_POOL "per-port-pool"
 #define CMD_LINE_OPT_MODE "mode"
 #define CMD_LINE_OPT_EVENTQ_SYNC "eventq-sched"
@@ -708,6 +711,7 @@ enum {
 	CMD_LINE_OPT_HASH_ENTRY_NUM_NUM,
 	CMD_LINE_OPT_PARSE_PTYPE_NUM,
 	CMD_LINE_OPT_DISABLE_RSS_NUM,
+	CMD_LINE_OPT_RELAX_RX_OFFLOAD_NUM,
 	CMD_LINE_OPT_RULE_IPV4_NUM,
 	CMD_LINE_OPT_RULE_IPV6_NUM,
 	CMD_LINE_OPT_ALG_NUM,
@@ -731,6 +735,7 @@ static const struct option lgopts[] = {
 	{CMD_LINE_OPT_MAX_PKT_LEN, 1, 0, CMD_LINE_OPT_MAX_PKT_LEN_NUM},
 	{CMD_LINE_OPT_HASH_ENTRY_NUM, 1, 0, CMD_LINE_OPT_HASH_ENTRY_NUM_NUM},
 	{CMD_LINE_OPT_PARSE_PTYPE, 0, 0, CMD_LINE_OPT_PARSE_PTYPE_NUM},
+	{CMD_LINE_OPT_RELAX_RX_OFFLOAD, 0, 0, CMD_LINE_OPT_RELAX_RX_OFFLOAD_NUM},
 	{CMD_LINE_OPT_DISABLE_RSS, 0, 0, CMD_LINE_OPT_DISABLE_RSS_NUM},
 	{CMD_LINE_OPT_PER_PORT_POOL, 0, 0, CMD_LINE_OPT_PARSE_PER_PORT_POOL},
 	{CMD_LINE_OPT_MODE, 1, 0, CMD_LINE_OPT_MODE_NUM},
@@ -857,6 +862,11 @@ parse_args(int argc, char **argv)
 			parse_ptype = 1;
 			break;
 
+		case CMD_LINE_OPT_RELAX_RX_OFFLOAD_NUM:
+			printf("Relax rx offload mode is enabled\n");
+			relax_rx_offload = 1;
+			break;
+
 		case CMD_LINE_OPT_DISABLE_RSS_NUM:
 			printf("Disable RX RSS\n");
 			disable_rss = 1;
@@ -1278,6 +1288,20 @@ l3fwd_poll_resource_setup(void)
 				local_port_conf.rx_adv_conf.rss_conf.rss_hf);
 		}
 
+		/* relax the rx offload requirement */
+		if ((local_port_conf.rxmode.offloads & dev_info.rx_offload_capa) !=
+			local_port_conf.rxmode.offloads) {
+			printf("Port %u requested Rx offloads 0x%"PRIx64" does not"
+				" match Rx offloads capabilities 0x%"PRIx64"\n",
+				portid, local_port_conf.rxmode.offloads,
+				dev_info.rx_offload_capa);
+			if (relax_rx_offload) {
+				local_port_conf.rxmode.offloads &= dev_info.rx_offload_capa;
+				printf("warning: modified the rx offload to 0x%"PRIx64" based on device"
+				" capability\n", local_port_conf.rxmode.offloads);
+			}
+		}
+
 		ret = rte_eth_dev_configure(portid, nb_rx_queue,
 					(uint16_t)n_tx_queue, &local_port_conf);
 		if (ret < 0)
-- 
2.34.1