netdev-dpdk: Clear IP packet type when no offload is requested.

OVS currently sets RTE_MBUF_F_TX_IPV[46] flags in early stages of the
packet reception and keeps track of the IP packet type as the packet
goes through OVS pipeline.
When a packet leaves OVS and hits a DPDK driver, OVS may not request IP
checksum offloading but leaves one of this packet type flag in ol_flags.

The DPDK api describes that RTE_MBUF_F_TX_IPV4 must be set when
requesting some Tx offloads (like RTE_MBUF_F_TX_IPSUM,
RTE_MBUF_F_TX_TCP_CKSUM, .., RTE_MBUF_F_TX_TCP_SEG).
Even though setting RTE_MBUF_F_TX_IPV4 without requesting a Tx offload
is undefined, this can confuse some drivers (like net/iavf) which then
reads zeroed l2_len and l3_len and ends up dropping the packet.

Reported-at: https://bugzilla.redhat.com/show_bug.cgi?id=2231081
Fixes: 5d11c47 ("userspace: Enable IP checksum offloading by default.")
Acked-by: Mike Pattrick <[email protected]>
Signed-off-by: David Marchand <[email protected]>
Signed-off-by: Ilya Maximets <[email protected]>

lib/netdev-dpdk.c

@@ -2431,6 +2431,7 @@ netdev_dpdk_prep_hwol_packet(struct netdev_dpdk *dev, struct rte_mbuf *mbuf)
 
     if (!(mbuf->ol_flags & (RTE_MBUF_F_TX_IP_CKSUM | RTE_MBUF_F_TX_L4_MASK
                             | RTE_MBUF_F_TX_TCP_SEG))) {
+        mbuf->ol_flags &= ~(RTE_MBUF_F_TX_IPV4 | RTE_MBUF_F_TX_IPV6);
         return true;
     }