diff --git a/sys/dev/virtio/network/if_vtnet.c b/sys/dev/virtio/network/if_vtnet.c
--- a/sys/dev/virtio/network/if_vtnet.c
+++ b/sys/dev/virtio/network/if_vtnet.c
@@ -28,6 +28,9 @@
 
 /* Driver for VirtIO network devices. */
 
+#include "opt_inet.h"
+#include "opt_inet6.h"
+
 #include <sys/param.h>
 #include <sys/eventhandler.h>
 #include <sys/systm.h>
@@ -82,9 +85,6 @@
 #include <dev/virtio/network/if_vtnetvar.h>
 #include "virtio_if.h"
 
-#include "opt_inet.h"
-#include "opt_inet6.h"
-
 #if defined(INET) || defined(INET6)
 #include <machine/in_cksum.h>
 #endif
@@ -1770,24 +1770,16 @@
 	sc = rxq->vtnrx_sc;
 
 	/*
-	 * NEEDS_CSUM corresponds to Linux's CHECKSUM_PARTIAL, but FreeBSD does
-	 * not have an analogous CSUM flag. The checksum has been validated,
-	 * but is incomplete (TCP/UDP pseudo header).
-	 *
-	 * The packet is likely from another VM on the same host that itself
-	 * performed checksum offloading so Tx/Rx is basically a memcpy and
-	 * the checksum has little value.
-	 *
-	 * Default to receiving the packet as-is for performance reasons, but
-	 * this can cause issues if the packet is to be forwarded because it
-	 * does not contain a valid checksum. This patch may be helpful:
-	 * https://reviews.freebsd.org/D6611. In the meantime, have the driver
-	 * compute the checksum if requested.
+	 * The packet is likely from another VM on the same host or from the
+	 * host that itself performed checksum offloading so Tx/Rx is basically
+	 * a memcpy and the checksum has little value so far.
 	 *
-	 * BMV: Need to add an CSUM_PARTIAL flag?
+	 * If the user don't want us to fix it up here by computing the
+	 * checksum, just forward the order to compute the checksum by setting
+	 * the corresponding mbuf flag (e.g., CSUM_TCP).
 	 */
 	if ((sc->vtnet_flags & VTNET_FLAG_FIXUP_NEEDS_CSUM) == 0) {
-		error = vtnet_rxq_csum_data_valid(rxq, m, etype, hoff, hdr);
+		error = virtio_net_rx_csum_by_offset(m, etype, hoff, hdr);
 		return (error);
 	}
 
@@ -2497,6 +2489,10 @@
 		hdr->csum_start = vtnet_gtoh16(sc, csum_start);
 		hdr->csum_offset = vtnet_gtoh16(sc, m->m_pkthdr.csum_data);
 		txq->vtntx_stats.vtxs_csum++;
+	} else if ((flags & (CSUM_DATA_VALID | CSUM_PSEUDO_HDR)) &&
+	           (proto == IPPROTO_TCP || proto == IPPROTO_UDP) &&
+	           (m->m_pkthdr.csum_data == 0xFFFF)) {
+		hdr->flags |= VIRTIO_NET_HDR_F_DATA_VALID;
 	}
 
 	if (flags & (CSUM_IP_TSO | CSUM_IP6_TSO)) {
@@ -2609,7 +2605,8 @@
 		m->m_flags &= ~M_VLANTAG;
 	}
 
-	if (m->m_pkthdr.csum_flags & VTNET_CSUM_ALL_OFFLOAD) {
+	if (m->m_pkthdr.csum_flags &
+	    (VTNET_CSUM_ALL_OFFLOAD | CSUM_DATA_VALID)) {
 		m = vtnet_txq_offload(txq, m, hdr);
 		if ((*m_head = m) == NULL) {
 			error = ENOBUFS;
diff --git a/sys/dev/virtio/network/virtio_net.h b/sys/dev/virtio/network/virtio_net.h
--- a/sys/dev/virtio/network/virtio_net.h
+++ b/sys/dev/virtio/network/virtio_net.h
@@ -261,19 +261,21 @@
 			struct virtio_net_hdr *hdr)
 {
 #if defined(INET) || defined(INET6)
+	bool isipv6;
 	int offset = hdr->csum_start + hdr->csum_offset;
-#endif
 
-	/* Only do a basic sanity check on the offset. */
+	/* Get IP version and do a basic sanity check on the offset. */
 	switch (eth_type) {
 #if defined(INET)
 	case ETHERTYPE_IP:
+		isipv6 = false;
 		if (__predict_false(offset < ip_start + sizeof(struct ip)))
 			return (1);
 		break;
 #endif
 #if defined(INET6)
 	case ETHERTYPE_IPV6:
+		isipv6 = true;
 		if (__predict_false(offset < ip_start + sizeof(struct ip6_hdr)))
 			return (1);
 		break;
@@ -284,6 +286,9 @@
 	}
 
 	/*
+	 * Forward the order to calculate the checksum in case this packet
+	 * will leave the host over a real interface with checksum offloading.
+	 *
 	 * Use the offset to determine the appropriate CSUM_* flags. This is
 	 * a bit dirty, but we can get by with it since the checksum offsets
 	 * happen to be different. We assume the host host does not do IPv4
@@ -291,15 +296,18 @@
 	 */
 	switch (hdr->csum_offset) {
 	case offsetof(struct udphdr, uh_sum):
+		m->m_pkthdr.csum_flags |= (isipv6 ? CSUM_UDP_IPV6 : CSUM_UDP);
+		break;
 	case offsetof(struct tcphdr, th_sum):
-		m->m_pkthdr.csum_flags |= CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
-		m->m_pkthdr.csum_data = 0xFFFF;
+		m->m_pkthdr.csum_flags |= (isipv6 ? CSUM_TCP_IPV6 : CSUM_TCP);
 		break;
 	default:
 		/* Here we should increment the rx_csum_bad_offset counter. */
 		return (1);
 	}
+	m->m_pkthdr.csum_data = hdr->csum_offset;
 
+#endif /* defined(INET) || defined(INET6) */
 	return (0);
 }
 
@@ -526,6 +534,12 @@
 		/* Here we should increment the tx_csum counter. */
 	}
 
+	if ((flags & (CSUM_DATA_VALID | CSUM_PSEUDO_HDR)) &&
+	    (proto == IPPROTO_TCP || proto == IPPROTO_UDP) &&
+	    (m->m_pkthdr.csum_data == 0xFFFF)) {
+		hdr->flags |= VIRTIO_NET_HDR_F_DATA_VALID;
+	}
+
 	if (flags & CSUM_TSO) {
 		if (__predict_false(proto != IPPROTO_TCP)) {
 			/* Likely failed to correctly parse the mbuf.
diff --git a/sys/net/if_tuntap.c b/sys/net/if_tuntap.c
--- a/sys/net/if_tuntap.c
+++ b/sys/net/if_tuntap.c
@@ -1757,7 +1757,8 @@
 		struct virtio_net_hdr_mrg_rxbuf vhdr;
 
 		bzero(&vhdr, sizeof(vhdr));
-		if (m->m_pkthdr.csum_flags & TAP_ALL_OFFLOAD) {
+		if (m->m_pkthdr.csum_flags &
+		    (TAP_ALL_OFFLOAD | CSUM_DATA_VALID)) {
 			m = virtio_net_tx_offload(ifp, m, false, &vhdr.hdr);
 		}