[PATCH 2/2] virtio-net: restore VIRTIO_HDR_F_DATA_VALID on receiving

[Stefan Bader]

From: Jason Wang <jasowang at redhat.com>

BugLink: http://bugs.launchpad.net/bugs/1685416

[ Upstream commit 6391a4481ba0796805d6581e42f9f0418c099e34 ]

Commit 501db511397f ("virtio: don't set VIRTIO_NET_HDR_F_DATA_VALID on
xmit") in fact disables VIRTIO_HDR_F_DATA_VALID on receiving path too,
fixing this by adding a hint (has_data_valid) and set it only on the
receiving path.

Cc: Rolf Neugebauer <rolf.neugebauer at docker.com>
Signed-off-by: Jason Wang <jasowang at redhat.com>
Acked-by: Rolf Neugebauer <rolf.neugebauer at docker.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
(cherry-picked from 1e7cbb413f63d8fa790c8dabc208ce2a02339c26 linux-4.9.y)
Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
---
 drivers/net/macvtap.c      | 2 +-
 drivers/net/tun.c          | 2 +-
 drivers/net/virtio_net.c   | 2 +-
 include/linux/virtio_net.h | 6 +++++-
 net/packet/af_packet.c     | 2 +-
 5 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 070e329..b2a680f 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -822,7 +822,7 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q,
 			return -EINVAL;
 
 		ret = virtio_net_hdr_from_skb(skb, &vnet_hdr,
-					      macvtap_is_little_endian(q));
+					      macvtap_is_little_endian(q), true);
 		if (ret)
 			BUG();
 
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 6f9df37..46264ed 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1382,7 +1382,7 @@ static ssize_t tun_put_user(struct tun_struct *tun,
 			return -EINVAL;
 
 		ret = virtio_net_hdr_from_skb(skb, &gso,
-					      tun_is_little_endian(tun));
+					      tun_is_little_endian(tun), true);
 		if (ret) {
 			struct skb_shared_info *sinfo = skb_shinfo(skb);
 			pr_err("unexpected GSO type: "
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index f7717e0..5cf97fe 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -839,7 +839,7 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff *skb)
 		hdr = skb_vnet_hdr(skb);
 
 	if (virtio_net_hdr_from_skb(skb, &hdr->hdr,
-				    virtio_is_little_endian(vi->vdev)))
+				    virtio_is_little_endian(vi->vdev), false))
 		BUG();
 
 	if (vi->mergeable_rx_bufs)
diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
index 40914bb..f211c34 100644
--- a/include/linux/virtio_net.h
+++ b/include/linux/virtio_net.h
@@ -56,7 +56,8 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
 
 static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb,
 					  struct virtio_net_hdr *hdr,
-					  bool little_endian)
+					  bool little_endian,
+					  bool has_data_valid)
 {
 	memset(hdr, 0, sizeof(*hdr));
 
@@ -91,6 +92,9 @@ static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb,
 				skb_checksum_start_offset(skb));
 		hdr->csum_offset = __cpu_to_virtio16(little_endian,
 				skb->csum_offset);
+	} else if (has_data_valid &&
+		   skb->ip_summed == CHECKSUM_UNNECESSARY) {
+		hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
 	} /* else everything is zero */
 
 	return 0;
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index e518c29..d9f28d3 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1972,7 +1972,7 @@ static int __packet_rcv_vnet(const struct sk_buff *skb,
 {
 	*vnet_hdr = (const struct virtio_net_hdr) { 0 };
 
-	if (virtio_net_hdr_from_skb(skb, vnet_hdr, vio_le()))
+	if (virtio_net_hdr_from_skb(skb, vnet_hdr, vio_le(), true))
 		BUG();
 
 	return 0;
-- 
2.7.4