Merge branch 'virtio_net-GSO-helpers'

Mike Rapoport says:

====================
virtio_net: use common code for virtio_net_hdr and skb GSO conversion

This patches introduce virtio_net_hdr_{from,to}_skb functions for
conversion of GSO information between skb and virtio_net_hdr.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/macvtap.c

@@ -627,93 +627,6 @@ static inline struct sk_buff *macvtap_alloc_skb(struct sock *sk, size_t prepad,
 	return skb;
 }
 
-/*
- * macvtap_skb_from_vnet_hdr and macvtap_skb_to_vnet_hdr should
- * be shared with the tun/tap driver.
- */
-static int macvtap_skb_from_vnet_hdr(struct macvtap_queue *q,
-				     struct sk_buff *skb,
-				     struct virtio_net_hdr *vnet_hdr)
-{
-	unsigned short gso_type = 0;
-	if (vnet_hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
-		switch (vnet_hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
-		case VIRTIO_NET_HDR_GSO_TCPV4:
-			gso_type = SKB_GSO_TCPV4;
-			break;
-		case VIRTIO_NET_HDR_GSO_TCPV6:
-			gso_type = SKB_GSO_TCPV6;
-			break;
-		case VIRTIO_NET_HDR_GSO_UDP:
-			gso_type = SKB_GSO_UDP;
-			break;
-		default:
-			return -EINVAL;
-		}
-
-		if (vnet_hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN)
-			gso_type |= SKB_GSO_TCP_ECN;
-
-		if (vnet_hdr->gso_size == 0)
-			return -EINVAL;
-	}
-
-	if (vnet_hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
-		if (!skb_partial_csum_set(skb, macvtap16_to_cpu(q, vnet_hdr->csum_start),
-					  macvtap16_to_cpu(q, vnet_hdr->csum_offset)))
-			return -EINVAL;
-	}
-
-	if (vnet_hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
-		skb_shinfo(skb)->gso_size = macvtap16_to_cpu(q, vnet_hdr->gso_size);
-		skb_shinfo(skb)->gso_type = gso_type;
-
-		/* Header must be checked, and gso_segs computed. */
-		skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
-		skb_shinfo(skb)->gso_segs = 0;
-	}
-	return 0;
-}
-
-static void macvtap_skb_to_vnet_hdr(struct macvtap_queue *q,
-				    const struct sk_buff *skb,
-				    struct virtio_net_hdr *vnet_hdr)
-{
-	memset(vnet_hdr, 0, sizeof(*vnet_hdr));
-
-	if (skb_is_gso(skb)) {
-		struct skb_shared_info *sinfo = skb_shinfo(skb);
-
-		/* This is a hint as to how much should be linear. */
-		vnet_hdr->hdr_len = cpu_to_macvtap16(q, skb_headlen(skb));
-		vnet_hdr->gso_size = cpu_to_macvtap16(q, sinfo->gso_size);
-		if (sinfo->gso_type & SKB_GSO_TCPV4)
-			vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
-		else if (sinfo->gso_type & SKB_GSO_TCPV6)
-			vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
-		else if (sinfo->gso_type & SKB_GSO_UDP)
-			vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
-		else
-			BUG();
-		if (sinfo->gso_type & SKB_GSO_TCP_ECN)
-			vnet_hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
-	} else
-		vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
-
-	if (skb->ip_summed == CHECKSUM_PARTIAL) {
-		vnet_hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
-		if (skb_vlan_tag_present(skb))
-			vnet_hdr->csum_start = cpu_to_macvtap16(q,
-				skb_checksum_start_offset(skb) + VLAN_HLEN);
-		else
-			vnet_hdr->csum_start = cpu_to_macvtap16(q,
-				skb_checksum_start_offset(skb));
-		vnet_hdr->csum_offset = cpu_to_macvtap16(q, skb->csum_offset);
-	} else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
-		vnet_hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
-	} /* else everything is zero */
-}
-
 /* Neighbour code has some assumptions on HH_DATA_MOD alignment */
 #define MACVTAP_RESERVE HH_DATA_OFF(ETH_HLEN)
 
@@ -812,7 +725,8 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
 	skb->protocol = eth_hdr(skb)->h_proto;
 
 	if (vnet_hdr_len) {
-		err = macvtap_skb_from_vnet_hdr(q, skb, &vnet_hdr);
+		err = virtio_net_hdr_to_skb(skb, &vnet_hdr,
+					    macvtap_is_little_endian(q));
 		if (err)
 			goto err_kfree;
 	}
@@ -880,7 +794,10 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q,
 		if (iov_iter_count(iter) < vnet_hdr_len)
 			return -EINVAL;
 
-		macvtap_skb_to_vnet_hdr(q, skb, &vnet_hdr);
+		ret = virtio_net_hdr_from_skb(skb, &vnet_hdr,
+					      macvtap_is_little_endian(q));
+		if (ret)
+			BUG();
 
 		if (copy_to_iter(&vnet_hdr, sizeof(vnet_hdr), iter) !=
 		    sizeof(vnet_hdr))

drivers/net/tun.c

@@ -1254,15 +1254,6 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 		return -EFAULT;
 	}
 
-	if (gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
-		if (!skb_partial_csum_set(skb, tun16_to_cpu(tun, gso.csum_start),
-					  tun16_to_cpu(tun, gso.csum_offset))) {
-			this_cpu_inc(tun->pcpu_stats->rx_frame_errors);
-			kfree_skb(skb);
-			return -EINVAL;
-		}
-	}
-
 	switch (tun->flags & TUN_TYPE_MASK) {
 	case IFF_TUN:
 		if (tun->flags & IFF_NO_PI) {
@@ -1289,37 +1280,11 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 		break;
 	}
 
-	if (gso.gso_type != VIRTIO_NET_HDR_GSO_NONE) {
-		pr_debug("GSO!\n");
-		switch (gso.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
-		case VIRTIO_NET_HDR_GSO_TCPV4:
-			skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
-			break;
-		case VIRTIO_NET_HDR_GSO_TCPV6:
-			skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
-			break;
-		case VIRTIO_NET_HDR_GSO_UDP:
-			skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
-			break;
-		default:
-			this_cpu_inc(tun->pcpu_stats->rx_frame_errors);
-			kfree_skb(skb);
-			return -EINVAL;
-		}
-
-		if (gso.gso_type & VIRTIO_NET_HDR_GSO_ECN)
-			skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
-
-		skb_shinfo(skb)->gso_size = tun16_to_cpu(tun, gso.gso_size);
-		if (skb_shinfo(skb)->gso_size == 0) {
-			this_cpu_inc(tun->pcpu_stats->rx_frame_errors);
-			kfree_skb(skb);
-			return -EINVAL;
-		}
-
-		/* Header must be checked, and gso_segs computed. */
-		skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
-		skb_shinfo(skb)->gso_segs = 0;
+	err = virtio_net_hdr_to_skb(skb, &gso, tun_is_little_endian(tun));
+	if (err) {
+		this_cpu_inc(tun->pcpu_stats->rx_frame_errors);
+		kfree_skb(skb);
+		return -EINVAL;
 	}
 
 	/* copy skb_ubuf_info for callback when skb has no error */
@@ -1399,46 +1364,26 @@ static ssize_t tun_put_user(struct tun_struct *tun,
 
 	if (vnet_hdr_sz) {
 		struct virtio_net_hdr gso = { 0 }; /* no info leak */
+		int ret;
+
 		if (iov_iter_count(iter) < vnet_hdr_sz)
 			return -EINVAL;
 
-		if (skb_is_gso(skb)) {
+		ret = virtio_net_hdr_from_skb(skb, &gso,
+					      tun_is_little_endian(tun));
+		if (ret) {
 			struct skb_shared_info *sinfo = skb_shinfo(skb);
-
-			/* This is a hint as to how much should be linear. */
-			gso.hdr_len = cpu_to_tun16(tun, skb_headlen(skb));
-			gso.gso_size = cpu_to_tun16(tun, sinfo->gso_size);
-			if (sinfo->gso_type & SKB_GSO_TCPV4)
-				gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
-			else if (sinfo->gso_type & SKB_GSO_TCPV6)
-				gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
-			else if (sinfo->gso_type & SKB_GSO_UDP)
-				gso.gso_type = VIRTIO_NET_HDR_GSO_UDP;
-			else {
-				pr_err("unexpected GSO type: "
-				       "0x%x, gso_size %d, hdr_len %d\n",
-				       sinfo->gso_type, tun16_to_cpu(tun, gso.gso_size),
-				       tun16_to_cpu(tun, gso.hdr_len));
-				print_hex_dump(KERN_ERR, "tun: ",
-					       DUMP_PREFIX_NONE,
-					       16, 1, skb->head,
-					       min((int)tun16_to_cpu(tun, gso.hdr_len), 64), true);
-				WARN_ON_ONCE(1);
-				return -EINVAL;
-			}
-			if (sinfo->gso_type & SKB_GSO_TCP_ECN)
-				gso.gso_type |= VIRTIO_NET_HDR_GSO_ECN;
-		} else
-			gso.gso_type = VIRTIO_NET_HDR_GSO_NONE;
-
-		if (skb->ip_summed == CHECKSUM_PARTIAL) {
-			gso.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
-			gso.csum_start = cpu_to_tun16(tun, skb_checksum_start_offset(skb) +
-						      vlan_hlen);
-			gso.csum_offset = cpu_to_tun16(tun, skb->csum_offset);
-		} else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
-			gso.flags = VIRTIO_NET_HDR_F_DATA_VALID;
-		} /* else everything is zero */
+			pr_err("unexpected GSO type: "
+			       "0x%x, gso_size %d, hdr_len %d\n",
+			       sinfo->gso_type, tun16_to_cpu(tun, gso.gso_size),
+			       tun16_to_cpu(tun, gso.hdr_len));
+			print_hex_dump(KERN_ERR, "tun: ",
+				       DUMP_PREFIX_NONE,
+				       16, 1, skb->head,
+				       min((int)tun16_to_cpu(tun, gso.hdr_len), 64), true);
+			WARN_ON_ONCE(1);
+			return -EINVAL;
+		}
 
 		if (copy_to_iter(&gso, sizeof(gso), iter) != sizeof(gso))
 			return -EFAULT;

drivers/net/virtio_net.c

@@ -479,51 +479,19 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
 	stats->rx_packets++;
 	u64_stats_update_end(&stats->rx_syncp);
 
-	if (hdr->hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
-		pr_debug("Needs csum!\n");
-		if (!skb_partial_csum_set(skb,
-			  virtio16_to_cpu(vi->vdev, hdr->hdr.csum_start),
-			  virtio16_to_cpu(vi->vdev, hdr->hdr.csum_offset)))
-			goto frame_err;
-	} else if (hdr->hdr.flags & VIRTIO_NET_HDR_F_DATA_VALID) {
+	if (hdr->hdr.flags & VIRTIO_NET_HDR_F_DATA_VALID)
 		skb->ip_summed = CHECKSUM_UNNECESSARY;
-	}
 
 	skb->protocol = eth_type_trans(skb, dev);
 	pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
 		 ntohs(skb->protocol), skb->len, skb->pkt_type);
 
-	if (hdr->hdr.gso_type != VIRTIO_NET_HDR_GSO_NONE) {
-		pr_debug("GSO!\n");
-		switch (hdr->hdr.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
-		case VIRTIO_NET_HDR_GSO_TCPV4:
-			skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
-			break;
-		case VIRTIO_NET_HDR_GSO_UDP:
-			skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
-			break;
-		case VIRTIO_NET_HDR_GSO_TCPV6:
-			skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
-			break;
-		default:
-			net_warn_ratelimited("%s: bad gso type %u.\n",
-					     dev->name, hdr->hdr.gso_type);
-			goto frame_err;
-		}
-
-		if (hdr->hdr.gso_type & VIRTIO_NET_HDR_GSO_ECN)
-			skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
-
-		skb_shinfo(skb)->gso_size = virtio16_to_cpu(vi->vdev,
-							    hdr->hdr.gso_size);
-		if (skb_shinfo(skb)->gso_size == 0) {
-			net_warn_ratelimited("%s: zero gso size.\n", dev->name);
-			goto frame_err;
-		}
-
-		/* Header must be checked, and gso_segs computed. */
-		skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
-		skb_shinfo(skb)->gso_segs = 0;
+	if (virtio_net_hdr_to_skb(skb, &hdr->hdr,
+				  virtio_is_little_endian(vi->vdev))) {
+		net_warn_ratelimited("%s: bad gso: type: %u, size: %u\n",
+				     dev->name, hdr->hdr.gso_type,
+				     hdr->hdr.gso_size);
+		goto frame_err;
 	}
 
 	napi_gro_receive(&rq->napi, skb);
@@ -868,35 +836,9 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff *skb)
 	else
 		hdr = skb_vnet_hdr(skb);
 
-	if (skb->ip_summed == CHECKSUM_PARTIAL) {
-		hdr->hdr.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
-		hdr->hdr.csum_start = cpu_to_virtio16(vi->vdev,
-						skb_checksum_start_offset(skb));
-		hdr->hdr.csum_offset = cpu_to_virtio16(vi->vdev,
-							 skb->csum_offset);
-	} else {
-		hdr->hdr.flags = 0;
-		hdr->hdr.csum_offset = hdr->hdr.csum_start = 0;
-	}
-
-	if (skb_is_gso(skb)) {
-		hdr->hdr.hdr_len = cpu_to_virtio16(vi->vdev, skb_headlen(skb));
-		hdr->hdr.gso_size = cpu_to_virtio16(vi->vdev,
-						    skb_shinfo(skb)->gso_size);
-		if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
-			hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
-		else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
-			hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
-		else if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
-			hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_UDP;
-		else
-			BUG();
-		if (skb_shinfo(skb)->gso_type & SKB_GSO_TCP_ECN)
-			hdr->hdr.gso_type |= VIRTIO_NET_HDR_GSO_ECN;
-	} else {
-		hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE;
-		hdr->hdr.gso_size = hdr->hdr.hdr_len = 0;
-	}
+	if (virtio_net_hdr_from_skb(skb, &hdr->hdr,
+				    virtio_is_little_endian(vi->vdev)))
+		BUG();
 
 	if (vi->mergeable_rx_bufs)
 		hdr->num_buffers = 0;

include/linux/virtio_net.h

+#ifndef _LINUX_VIRTIO_NET_H
+#define _LINUX_VIRTIO_NET_H
+
+#include <linux/if_vlan.h>
+#include <uapi/linux/virtio_net.h>
+
+static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
+					const struct virtio_net_hdr *hdr,
+					bool little_endian)
+{
+	unsigned short gso_type = 0;
+
+	if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
+		switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
+		case VIRTIO_NET_HDR_GSO_TCPV4:
+			gso_type = SKB_GSO_TCPV4;
+			break;
+		case VIRTIO_NET_HDR_GSO_TCPV6:
+			gso_type = SKB_GSO_TCPV6;
+			break;
+		case VIRTIO_NET_HDR_GSO_UDP:
+			gso_type = SKB_GSO_UDP;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		if (hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN)
+			gso_type |= SKB_GSO_TCP_ECN;
+
+		if (hdr->gso_size == 0)
+			return -EINVAL;
+	}
+
+	if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
+		u16 start = __virtio16_to_cpu(little_endian, hdr->csum_start);
+		u16 off = __virtio16_to_cpu(little_endian, hdr->csum_offset);
+
+		if (!skb_partial_csum_set(skb, start, off))
+			return -EINVAL;
+	}
+
+	if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
+		u16 gso_size = __virtio16_to_cpu(little_endian, hdr->gso_size);
+
+		skb_shinfo(skb)->gso_size = gso_size;
+		skb_shinfo(skb)->gso_type = gso_type;
+
+		/* Header must be checked, and gso_segs computed. */
+		skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
+		skb_shinfo(skb)->gso_segs = 0;
+	}
+
+	return 0;
+}
+
+static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb,
+					  struct virtio_net_hdr *hdr,
+					  bool little_endian)
+{
+	memset(hdr, 0, sizeof(*hdr));
+
+	if (skb_is_gso(skb)) {
+		struct skb_shared_info *sinfo = skb_shinfo(skb);
+
+		/* This is a hint as to how much should be linear. */
+		hdr->hdr_len = __cpu_to_virtio16(little_endian,
+						 skb_headlen(skb));
+		hdr->gso_size = __cpu_to_virtio16(little_endian,
+						  sinfo->gso_size);
+		if (sinfo->gso_type & SKB_GSO_TCPV4)
+			hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
+		else if (sinfo->gso_type & SKB_GSO_TCPV6)
+			hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
+		else if (sinfo->gso_type & SKB_GSO_UDP)
+			hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
+		else
+			return -EINVAL;
+		if (sinfo->gso_type & SKB_GSO_TCP_ECN)
+			hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
+	} else
+		hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
+
+	if (skb->ip_summed == CHECKSUM_PARTIAL) {
+		hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
+		if (skb_vlan_tag_present(skb))
+			hdr->csum_start = __cpu_to_virtio16(little_endian,
+				skb_checksum_start_offset(skb) + VLAN_HLEN);
+		else
+			hdr->csum_start = __cpu_to_virtio16(little_endian,
+				skb_checksum_start_offset(skb));
+		hdr->csum_offset = __cpu_to_virtio16(little_endian,
+				skb->csum_offset);
+	} else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
+		hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
+	} /* else everything is zero */
+
+	return 0;
+}
+
+#endif /* _LINUX_VIRTIO_BYTEORDER */

include/uapi/linux/virtio_net.h

-#ifndef _LINUX_VIRTIO_NET_H
-#define _LINUX_VIRTIO_NET_H
+#ifndef _UAPI_LINUX_VIRTIO_NET_H
+#define _UAPI_LINUX_VIRTIO_NET_H
 /* This header is BSD licensed so anyone can use the definitions to implement
  * compatible drivers/servers.
  *
@@ -245,4 +245,4 @@ struct virtio_net_ctrl_mq {
 #define VIRTIO_NET_CTRL_GUEST_OFFLOADS   5
 #define VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET        0
 
-#endif /* _LINUX_VIRTIO_NET_H */
+#endif /* _UAPI_LINUX_VIRTIO_NET_H */

net/packet/af_packet.c

@@ -1979,40 +1979,8 @@ static int __packet_rcv_vnet(const struct sk_buff *skb,
 {
 	*vnet_hdr = (const struct virtio_net_hdr) { 0 };
 
-	if (skb_is_gso(skb)) {
-		struct skb_shared_info *sinfo = skb_shinfo(skb);
-
-		/* This is a hint as to how much should be linear. */
-		vnet_hdr->hdr_len =
-			__cpu_to_virtio16(vio_le(), skb_headlen(skb));
-		vnet_hdr->gso_size =
-			__cpu_to_virtio16(vio_le(), sinfo->gso_size);
-
-		if (sinfo->gso_type & SKB_GSO_TCPV4)
-			vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
-		else if (sinfo->gso_type & SKB_GSO_TCPV6)
-			vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
-		else if (sinfo->gso_type & SKB_GSO_UDP)
-			vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
-		else if (sinfo->gso_type & SKB_GSO_FCOE)
-			return -EINVAL;
-		else
-			BUG();
-
-		if (sinfo->gso_type & SKB_GSO_TCP_ECN)
-			vnet_hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
-	} else
-		vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
-
-	if (skb->ip_summed == CHECKSUM_PARTIAL) {
-		vnet_hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
-		vnet_hdr->csum_start = __cpu_to_virtio16(vio_le(),
-				  skb_checksum_start_offset(skb));
-		vnet_hdr->csum_offset = __cpu_to_virtio16(vio_le(),
-						 skb->csum_offset);
-	} else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
-		vnet_hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
-	} /* else everything is zero */
+	if (virtio_net_hdr_from_skb(skb, vnet_hdr, vio_le()))
+		BUG();
 
 	return 0;
 }