vhost: fix IP checksum

There is no way to bypass IP checksum verification in Linux
kernel, no matter skb->ip_summed is assigned as CHECKSUM_UNNECESSARY
or CHECKSUM_PARTIAL.

So any packets with bad IP checksum will be dropped at VM IP layer.

To correct, we check this flag PKT_TX_IP_CKSUM to calculate IP csum.

Fixes: 859b480d5afd ("vhost: add guest offload setting")
Cc: stable@dpdk.org
Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Acked-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>

diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index d095f64..88b74f1 100644 (file)
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -143,6 +143,15 @@ virtio_enqueue_offload(struct rte_mbuf *m_buf, struct virtio_net_hdr *net_hdr)
                ASSIGN_UNLESS_EQUAL(net_hdr->flags, 0);
        }
 
+       /* IP cksum verification cannot be bypassed, then calculate here */
+       if (m_buf->ol_flags & PKT_TX_IP_CKSUM) {
+               struct ipv4_hdr *ipv4_hdr;
+
+               ipv4_hdr = rte_pktmbuf_mtod_offset(m_buf, struct ipv4_hdr *,
+                                                  m_buf->l2_len);
+               ipv4_hdr->hdr_checksum = rte_ipv4_cksum(ipv4_hdr);
+       }
+
        if (m_buf->ol_flags & PKT_TX_TCP_SEG) {
                if (m_buf->ol_flags & PKT_TX_IPV4)
                        net_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;