5 files changed, 9 insertions, 0 deletions

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 6696e56e6320..ecee0fe65a97 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -508,6 +508,8 @@ static int macvtap_skb_to_vnet_hdr(const struct sk_buff *skb,
                 vnet_hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
                 vnet_hdr->csum_start = skb_checksum_start_offset(skb);
                 vnet_hdr->csum_offset = skb->csum_offset;
+        } else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
+                vnet_hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
         } /* else everything is zero */
 
         return 0;
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index ef68e13c042d..4dab85eecb60 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -788,6 +788,8 @@ static ssize_t tun_put_user(struct tun_struct *tun,
                         gso.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
                         gso.csum_start = skb_checksum_start_offset(skb);
                         gso.csum_offset = skb->csum_offset;
+                } else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
+                        gso.flags = VIRTIO_NET_HDR_F_DATA_VALID;
                 } /* else everything is zero */
 
                 if (unlikely(memcpy_toiovecend(iv, (void *)&gso, total,
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index f6853247a620..be3686a298da 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -274,6 +274,8 @@ static void receive_buf(struct net_device *dev, void *buf, unsigned int len)
                                           hdr->hdr.csum_start,
                                           hdr->hdr.csum_offset))
                         goto frame_err;
+        } else if (hdr->hdr.flags & VIRTIO_NET_HDR_F_DATA_VALID) {
+                skb->ip_summed = CHECKSUM_UNNECESSARY;
         }
 
         skb->protocol = eth_type_trans(skb, dev);
diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
index 136040bba3e3..970d5a2a9047 100644
--- a/include/linux/virtio_net.h
+++ b/include/linux/virtio_net.h
@@ -63,6 +63,7 @@ struct virtio_net_config {
  * specify GSO or CSUM features, you can simply ignore the header. */
 struct virtio_net_hdr {
 #define VIRTIO_NET_HDR_F_NEEDS_CSUM     1       // Use csum_start, csum_offset
+#define VIRTIO_NET_HDR_F_DATA_VALID     2       // Csum is valid
         __u8 flags;
 #define VIRTIO_NET_HDR_GSO_NONE         0       // Not a GSO frame
 #define VIRTIO_NET_HDR_GSO_TCPV4        1       // GSO frame, IPv4 TCP (TSO)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 67f6749a0a45..b54ec41adea9 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1685,6 +1685,8 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock,
                         vnet_hdr.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
                         vnet_hdr.csum_start = skb_checksum_start_offset(skb);
                         vnet_hdr.csum_offset = skb->csum_offset;
+                } else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
+                        vnet_hdr.flags = VIRTIO_NET_HDR_F_DATA_VALID;
                 } /* else everything is zero */
 
                 err = memcpy_toiovec(msg->msg_iov, (void *)&vnet_hdr,