[PATCH v1] examples/l3fwd: relax the RSS/Offload requirement

[Trevor Tao <taozj888@163.com>]

Now the port Rx mq_mode had been set to RTE_ETH_MQ_RX_RSS, and offload
mode set to RTE_ETH_RX_OFFLOAD_CHECKSUM by default, but some hardware
and/or virtual interface does not support the RSS and offload mode
presupposed, e.g., some virtio interfaces in the cloud don't support
RSS and 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:

virtio_dev_configure(): RSS support requested but not supported by
the device
Port0 dev_configure = -95

and:
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, 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 the
hw support missing.

Fixes: af75078fece3 ("first public release")
Cc: stable@dpdk.org

Signed-off-by: Trevor Tao <taozj888@163.com>
---
 examples/l3fwd/l3fwd.h | 12 +++++++++++-
 examples/l3fwd/main.c  | 21 +++++++++++++++++++--
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/examples/l3fwd/l3fwd.h b/examples/l3fwd/l3fwd.h
index b55855c932..cc10643c4b 100644
--- a/examples/l3fwd/l3fwd.h
+++ b/examples/l3fwd/l3fwd.h
@@ -115,6 +115,8 @@ extern struct acl_algorithms acl_alg[];
 
 extern uint32_t max_pkt_len;
 
+extern struct rte_eth_conf port_conf;
+
 /* Send burst of packets on an output interface */
 static inline int
 send_burst(struct lcore_conf *qconf, uint16_t n, uint16_t port)
@@ -170,7 +172,15 @@ 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 ((port_conf.rxmode.offloads & RTE_ETH_RX_OFFLOAD_IPV4_CKSUM) == 0) {
+		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/main.c b/examples/l3fwd/main.c
index 6063eb1399..37aec64718 100644
--- a/examples/l3fwd/main.c
+++ b/examples/l3fwd/main.c
@@ -117,7 +117,7 @@ static struct lcore_params * lcore_params = lcore_params_array_default;
 static uint16_t nb_lcore_params = sizeof(lcore_params_array_default) /
 				sizeof(lcore_params_array_default[0]);
 
-static struct rte_eth_conf port_conf = {
+struct rte_eth_conf port_conf = {
 	.rxmode = {
 		.mq_mode = RTE_ETH_MQ_RX_RSS,
 		.offloads = RTE_ETH_RX_OFFLOAD_CHECKSUM,
@@ -1257,8 +1257,12 @@ l3fwd_poll_resource_setup(void)
 		local_port_conf.rx_adv_conf.rss_conf.rss_hf &=
 			dev_info.flow_type_rss_offloads;
 
-		if (dev_info.max_rx_queues == 1)
+		/* relax the rx rss requirement */
+		if (dev_info.max_rx_queues == 1 || !local_port_conf.rx_adv_conf.rss_conf.rss_hf) {
+			printf("warning: modified the rx mq_mode to RTE_ETH_MQ_RX_NONE base on"
+				" device capability\n");
 			local_port_conf.rxmode.mq_mode = RTE_ETH_MQ_RX_NONE;
+		}
 
 		if (local_port_conf.rx_adv_conf.rss_conf.rss_hf !=
 				port_conf.rx_adv_conf.rss_conf.rss_hf) {
@@ -1269,6 +1273,19 @@ 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);
+			local_port_conf.rxmode.offloads &= dev_info.rx_offload_capa;
+			port_conf.rxmode.offloads = local_port_conf.rxmode.offloads;
+			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