The Virtio specification requires that in case of checksum
offloading, the pseudo-header checksum must be set in the
L4 header.
When received from another Vhost-user port, the packet
checksum might already contain the pseudo-header checksum
but we have no way to know it. So we have no other choice
than doing the pseudo-header checksum systematically.
This patch handles this using the rte_net_intel_cksum_prepare()
helper.
Fixes: 859b480d5afd ("vhost: add guest offload setting")
Cc: sta...@dpdk.org
Signed-off-by: Maxime Coquelin <maxime.coque...@redhat.com>
---
lib/vhost/virtio_net.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
index 5f432b0d77..c0ff3357a8 100644
--- a/lib/vhost/virtio_net.c
+++ b/lib/vhost/virtio_net.c
@@ -548,6 +548,16 @@ virtio_enqueue_offload(struct rte_mbuf *m_buf, struct
virtio_net_hdr *net_hdr)
csum_l4 |= RTE_MBUF_F_TX_TCP_CKSUM;
if (csum_l4) {
+ /*
+ * Pseudo-header checksum must be set as per Virtio spec.
+ *
+ * Note: We don't propagate rte_net_intel_cksum_prepare()
+ * errors, as it would have an impact on performance, and an
+ * error would mean the packet is dropped by the guest instead
+ * of being dropped here.
+ */
+ rte_net_intel_cksum_prepare(m_buf);
+
net_hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
net_hdr->csum_start = m_buf->l2_len + m_buf->l3_len;
--
2.35.1
