[dpdk-dev] [PATCH v2] app/testpmd: fix l4 sw csum over multi segments

[Xiaoyun Li]

In csum forwarding mode, software UDP/TCP csum calculation only takes
the first segment into account while using the whole packet length so
the calculation will read invalid memory region with multi-segments
packets and will get wrong value.
This patch fixes this issue.

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

Signed-off-by: Xiaoyun Li <xiaoyun...@intel.com>
---
v2:
 * Use static stack memory instead of dynamic allocating in datapath.
---
 app/test-pmd/csumonly.c | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/app/test-pmd/csumonly.c b/app/test-pmd/csumonly.c
index 090797318a..9f78ac74e1 100644
--- a/app/test-pmd/csumonly.c
+++ b/app/test-pmd/csumonly.c
@@ -56,6 +56,11 @@
 #define GRE_SUPPORTED_FIELDS   (GRE_CHECKSUM_PRESENT | GRE_KEY_PRESENT |\
                                 GRE_SEQUENCE_PRESENT)
 
+/* When UDP or TCP or outer UDP csum offload is off, sw l4 csum is needed */
+#define UDP_TCP_CSUM            (DEV_TX_OFFLOAD_UDP_CKSUM |\
+                                DEV_TX_OFFLOAD_TCP_CKSUM |\
+                                DEV_TX_OFFLOAD_OUTER_UDP_CKSUM)
+
 /* We cannot use rte_cpu_to_be_16() on a constant in a switch/case */
 #if RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN
 #define _htons(x) ((uint16_t)((((x) & 0x00ffU) << 8) | (((x) & 0xff00U) >> 8)))
@@ -602,12 +607,8 @@ process_outer_cksums(void *outer_l3_hdr, struct 
testpmd_offload_info *info,
        /* do not recalculate udp cksum if it was 0 */
        if (udp_hdr->dgram_cksum != 0) {
                udp_hdr->dgram_cksum = 0;
-               if (info->outer_ethertype == _htons(RTE_ETHER_TYPE_IPV4))
-                       udp_hdr->dgram_cksum =
-                               rte_ipv4_udptcp_cksum(ipv4_hdr, udp_hdr);
-               else
-                       udp_hdr->dgram_cksum =
-                               rte_ipv6_udptcp_cksum(ipv6_hdr, udp_hdr);
+               udp_hdr->dgram_cksum = get_udptcp_checksum(outer_l3_hdr,
+                                       udp_hdr, info->outer_ethertype);
        }
 
        return ol_flags;
@@ -877,7 +878,17 @@ pkt_burst_checksum_forward(struct fwd_stream *fs)
                rte_ether_addr_copy(&ports[fs->tx_port].eth_addr,
                                &eth_hdr->src_addr);
                parse_ethernet(eth_hdr, &info);
-               l3_hdr = (char *)eth_hdr + info.l2_len;
+               /* When sw csum is needed, multi-segs needs a buf to contain
+                * the whole packet for later UDP/TCP csum calculation.
+                */
+               if (m->nb_segs > 1 && !(tx_ol_flags & PKT_TX_TCP_SEG) &&
+                   !(tx_offloads & UDP_TCP_CSUM)) {
+                       char l3_buf[RTE_IPV4_MAX_PKT_LEN + 1];
+                       rte_pktmbuf_read(m, info.l2_len,
+                                        info.pkt_len - info.l2_len, l3_buf);
+                       l3_hdr = l3_buf;
+               } else
+                       l3_hdr = (char *)eth_hdr + info.l2_len;
 
                /* check if it's a supported tunnel */
                if (txp->parse_tunnel) {
-- 
2.25.1