vhost: fix TCP checksum

As PKT_TX_TCP_SEG flag in mbuf->ol_flags implies PKT_TX_TCP_CKSUM,
applications, e.g., testpmd, don't set PKT_TX_TCP_CKSUM when TSO
is set.

This leads to that packets get dropped in VM tcp stack layer because
of bad TCP csum.

To fix this, we make sure TCP NEEDS_CSUM info is set into virtio net
header when PKT_TX_TCP_SEG is set, so that VM tcp stack will not
check the TCP 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 ebfda1c..d095f64 100644 (file)
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -114,11 +114,16 @@ update_shadow_used_ring(struct vhost_virtqueue *vq,
 static void
 virtio_enqueue_offload(struct rte_mbuf *m_buf, struct virtio_net_hdr *net_hdr)
 {
-       if (m_buf->ol_flags & PKT_TX_L4_MASK) {
+       uint64_t csum_l4 = m_buf->ol_flags & PKT_TX_L4_MASK;
+
+       if (m_buf->ol_flags & PKT_TX_TCP_SEG)
+               csum_l4 |= PKT_TX_TCP_CKSUM;
+
+       if (csum_l4) {
                net_hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
                net_hdr->csum_start = m_buf->l2_len + m_buf->l3_len;
 
-               switch (m_buf->ol_flags & PKT_TX_L4_MASK) {
+               switch (csum_l4) {
                case PKT_TX_TCP_CKSUM:
                        net_hdr->csum_offset = (offsetof(struct tcp_hdr,
                                                cksum));