Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next

Pull networking updates from David Miller:

 1) The addition of nftables.  No longer will we need protocol aware
    firewall filtering modules, it can all live in userspace.

    At the core of nftables is a, for lack of a better term, virtual
    machine that executes byte codes to inspect packet or metadata
    (arriving interface index, etc.) and make verdict decisions.

    Besides support for loading packet contents and comparing them, the
    interpreter supports lookups in various datastructures as
    fundamental operations.  For example sets are supports, and
    therefore one could create a set of whitelist IP address entries
    which have ACCEPT verdicts attached to them, and use the appropriate
    byte codes to do such lookups.

    Since the interpreted code is composed in userspace, userspace can
    do things like optimize things before giving it to the kernel.

    Another major improvement is the capability of atomically updating
    portions of the ruleset.  In the existing netfilter implementation,
    one has to update the entire rule set in order to make a change and
    this is very expensive.

    Userspace tools exist to create nftables rules using existing
    netfilter rule sets, but both kernel implementations will need to
    co-exist for quite some time as we transition from the old to the
    new stuff.

    Kudos to Patrick McHardy, Pablo Neira Ayuso, and others who have
    worked so hard on this.

 2) Daniel Borkmann and Hannes Frederic Sowa made several improvements
    to our pseudo-random number generator, mostly used for things like
    UDP port randomization and netfitler, amongst other things.

    In particular the taus88 generater is updated to taus113, and test
    cases are added.

 3) Support 64-bit rates in HTB and TBF schedulers, from Eric Dumazet
    and Yang Yingliang.

 4) Add support for new 577xx tigon3 chips to tg3 driver, from Nithin
    Sujir.

 5) Fix two fatal flaws in TCP dynamic right sizing, from Eric Dumazet,
    Neal Cardwell, and Yuchung Cheng.

 6) Allow IP_TOS and IP_TTL to be specified in sendmsg() ancillary
    control message data, much like other socket option attributes.
    From Francesco Fusco.

 7) Allow applications to specify a cap on the rate computed
    automatically by the kernel for pacing flows, via a new
    SO_MAX_PACING_RATE socket option.  From Eric Dumazet.

 8) Make the initial autotuned send buffer sizing in TCP more closely
    reflect actual needs, from Eric Dumazet.

 9) Currently early socket demux only happens for TCP sockets, but we
    can do it for connected UDP sockets too.  Implementation from Shawn
    Bohrer.

10) Refactor inet socket demux with the goal of improving hash demux
    performance for listening sockets.  With the main goals being able
    to use RCU lookups on even request sockets, and eliminating the
    listening lock contention.  From Eric Dumazet.

11) The bonding layer has many demuxes in it's fast path, and an RCU
    conversion was started back in 3.11, several changes here extend the
    RCU usage to even more locations.  From Ding Tianhong and Wang
    Yufen, based upon suggestions by Nikolay Aleksandrov and Veaceslav
    Falico.

12) Allow stackability of segmentation offloads to, in particular, allow
    segmentation offloading over tunnels.  From Eric Dumazet.

13) Significantly improve the handling of secret keys we input into the
    various hash functions in the inet hashtables, TCP fast open, as
    well as syncookies.  From Hannes Frederic Sowa.  The key fundamental
    operation is "net_get_random_once()" which uses static keys.

    Hannes even extended this to ipv4/ipv6 fragmentation handling and
    our generic flow dissector.

14) The generic driver layer takes care now to set the driver data to
    NULL on device removal, so it's no longer necessary for drivers to
    explicitly set it to NULL any more.  Many drivers have been cleaned
    up in this way, from Jingoo Han.

15) Add a BPF based packet scheduler classifier, from Daniel Borkmann.

16) Improve CRC32 interfaces and generic SKB checksum iterators so that
    SCTP's checksumming can more cleanly be handled.  Also from Daniel
    Borkmann.

17) Add a new PMTU discovery mode, IP_PMTUDISC_INTERFACE, which forces
    using the interface MTU value.  This helps avoid PMTU attacks,
    particularly on DNS servers.  From Hannes Frederic Sowa.

18) Use generic XPS for transmit queue steering rather than internal
    (re-)implementation in virtio-net.  From Jason Wang.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1622 commits)
  random32: add test cases for taus113 implementation
  random32: upgrade taus88 generator to taus113 from errata paper
  random32: move rnd_state to linux/random.h
  random32: add prandom_reseed_late() and call when nonblocking pool becomes initialized
  random32: add periodic reseeding
  random32: fix off-by-one in seeding requirement
  PHY: Add RTL8201CP phy_driver to realtek
  xtsonic: add missing platform_set_drvdata() in xtsonic_probe()
  macmace: add missing platform_set_drvdata() in mace_probe()
  ethernet/arc/arc_emac: add missing platform_set_drvdata() in arc_emac_probe()
  ipv6: protect for_each_sk_fl_rcu in mem_check with rcu_read_lock_bh
  vlan: Implement vlan_dev_get_egress_qos_mask as an inline.
  ixgbe: add warning when max_vfs is out of range.
  igb: Update link modes display in ethtool
  netfilter: push reasm skb through instead of original frag skbs
  ip6_output: fragment outgoing reassembled skb properly
  MAINTAINERS: mv643xx_eth: take over maintainership from Lennart
  net_sched: tbf: support of 64bit rates
  ixgbe: deleting dfwd stations out of order can cause null ptr deref
  ixgbe: fix build err, num_rx_queues is only available with CONFIG_RPS
  ...

4 files changed, 311 insertions, 63 deletions

diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index 400fea1de08..08ae01b41c8 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -87,9 +87,13 @@ struct pending_tx_info {
 struct xenvif_rx_meta {
 	int id;
 	int size;
+	int gso_type;
 	int gso_size;
 };
 
+#define GSO_BIT(type) \
+	(1 << XEN_NETIF_GSO_TYPE_ ## type)
+
 /* Discriminate from any valid pending_idx value. */
 #define INVALID_PENDING_IDX 0xFFFF
 
@@ -150,10 +154,12 @@ struct xenvif {
 	u8               fe_dev_addr[6];
 
 	/* Frontend feature information. */
+	int gso_mask;
+	int gso_prefix_mask;
+
 	u8 can_sg:1;
-	u8 gso:1;
-	u8 gso_prefix:1;
-	u8 csum:1;
+	u8 ip_csum:1;
+	u8 ipv6_csum:1;
 
 	/* Internal feature information. */
 	u8 can_queue:1;	    /* can queue packets for receiver? */
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 459935a6bfa..b78ee10a956 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -214,10 +214,14 @@ static netdev_features_t xenvif_fix_features(struct net_device *dev,
 
 	if (!vif->can_sg)
 		features &= ~NETIF_F_SG;
-	if (!vif->gso && !vif->gso_prefix)
+	if (~(vif->gso_mask | vif->gso_prefix_mask) & GSO_BIT(TCPV4))
 		features &= ~NETIF_F_TSO;
-	if (!vif->csum)
+	if (~(vif->gso_mask | vif->gso_prefix_mask) & GSO_BIT(TCPV6))
+		features &= ~NETIF_F_TSO6;
+	if (!vif->ip_csum)
 		features &= ~NETIF_F_IP_CSUM;
+	if (!vif->ipv6_csum)
+		features &= ~NETIF_F_IPV6_CSUM;
 
 	return features;
 }
@@ -306,7 +310,7 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
 	vif->domid  = domid;
 	vif->handle = handle;
 	vif->can_sg = 1;
-	vif->csum = 1;
+	vif->ip_csum = 1;
 	vif->dev = dev;
 
 	vif->credit_bytes = vif->remaining_credit = ~0UL;
@@ -315,8 +319,10 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
 	vif->credit_window_start = get_jiffies_64();
 
 	dev->netdev_ops	= &xenvif_netdev_ops;
-	dev->hw_features = NETIF_F_SG | NETIF_F_IP_CSUM | NETIF_F_TSO;
-	dev->features = dev->hw_features;
+	dev->hw_features = NETIF_F_SG |
+		NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM |
+		NETIF_F_TSO | NETIF_F_TSO6;
+	dev->features = dev->hw_features | NETIF_F_RXCSUM;
 	SET_ETHTOOL_OPS(dev, &xenvif_ethtool_ops);
 
 	dev->tx_queue_len = XENVIF_QUEUE_LENGTH;
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 900da4b243a..919b6509455 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -109,15 +109,12 @@ static inline unsigned long idx_to_kaddr(struct xenvif *vif,
 	return (unsigned long)pfn_to_kaddr(idx_to_pfn(vif, idx));
 }
 
-/*
- * This is the amount of packet we copy rather than map, so that the
- * guest can't fiddle with the contents of the headers while we do
- * packet processing on them (netfilter, routing, etc).
+/* This is a miniumum size for the linear area to avoid lots of
+ * calls to __pskb_pull_tail() as we set up checksum offsets. The
+ * value 128 was chosen as it covers all IPv4 and most likely
+ * IPv6 headers.
  */
-#define PKT_PROT_LEN    (ETH_HLEN + \
-			 VLAN_HLEN + \
-			 sizeof(struct iphdr) + MAX_IPOPTLEN + \
-			 sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE)
+#define PKT_PROT_LEN 128
 
 static u16 frag_get_pending_idx(skb_frag_t *frag)
 {
@@ -145,7 +142,7 @@ static int max_required_rx_slots(struct xenvif *vif)
 	int max = DIV_ROUND_UP(vif->dev->mtu, PAGE_SIZE);
 
 	/* XXX FIXME: RX path dependent on MAX_SKB_FRAGS */
-	if (vif->can_sg || vif->gso || vif->gso_prefix)
+	if (vif->can_sg || vif->gso_mask || vif->gso_prefix_mask)
 		max += MAX_SKB_FRAGS + 1; /* extra_info + frags */
 
 	return max;
@@ -317,6 +314,7 @@ static struct xenvif_rx_meta *get_next_rx_buffer(struct xenvif *vif,
 	req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
 
 	meta = npo->meta + npo->meta_prod++;
+	meta->gso_type = XEN_NETIF_GSO_TYPE_NONE;
 	meta->gso_size = 0;
 	meta->size = 0;
 	meta->id = req->id;
@@ -339,6 +337,7 @@ static void xenvif_gop_frag_copy(struct xenvif *vif, struct sk_buff *skb,
 	struct gnttab_copy *copy_gop;
 	struct xenvif_rx_meta *meta;
 	unsigned long bytes;
+	int gso_type;
 
 	/* Data must not cross a page boundary. */
 	BUG_ON(size + offset > PAGE_SIZE<<compound_order(page));
@@ -397,7 +396,14 @@ static void xenvif_gop_frag_copy(struct xenvif *vif, struct sk_buff *skb,
 		}
 
 		/* Leave a gap for the GSO descriptor. */
-		if (*head && skb_shinfo(skb)->gso_size && !vif->gso_prefix)
+		if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
+			gso_type = XEN_NETIF_GSO_TYPE_TCPV4;
+		else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
+			gso_type = XEN_NETIF_GSO_TYPE_TCPV6;
+		else
+			gso_type = XEN_NETIF_GSO_TYPE_NONE;
+
+		if (*head && ((1 << gso_type) & vif->gso_mask))
 			vif->rx.req_cons++;
 
 		*head = 0; /* There must be something in this buffer now. */
@@ -428,14 +434,28 @@ static int xenvif_gop_skb(struct sk_buff *skb,
 	unsigned char *data;
 	int head = 1;
 	int old_meta_prod;
+	int gso_type;
+	int gso_size;
 
 	old_meta_prod = npo->meta_prod;
 
+	if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4) {
+		gso_type = XEN_NETIF_GSO_TYPE_TCPV4;
+		gso_size = skb_shinfo(skb)->gso_size;
+	} else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6) {
+		gso_type = XEN_NETIF_GSO_TYPE_TCPV6;
+		gso_size = skb_shinfo(skb)->gso_size;
+	} else {
+		gso_type = XEN_NETIF_GSO_TYPE_NONE;
+		gso_size = 0;
+	}
+
 	/* Set up a GSO prefix descriptor, if necessary */
-	if (skb_shinfo(skb)->gso_size && vif->gso_prefix) {
+	if ((1 << skb_shinfo(skb)->gso_type) & vif->gso_prefix_mask) {
 		req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
 		meta = npo->meta + npo->meta_prod++;
-		meta->gso_size = skb_shinfo(skb)->gso_size;
+		meta->gso_type = gso_type;
+		meta->gso_size = gso_size;
 		meta->size = 0;
 		meta->id = req->id;
 	}
@@ -443,10 +463,13 @@ static int xenvif_gop_skb(struct sk_buff *skb,
 	req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
 	meta = npo->meta + npo->meta_prod++;
 
-	if (!vif->gso_prefix)
-		meta->gso_size = skb_shinfo(skb)->gso_size;
-	else
+	if ((1 << gso_type) & vif->gso_mask) {
+		meta->gso_type = gso_type;
+		meta->gso_size = gso_size;
+	} else {
+		meta->gso_type = XEN_NETIF_GSO_TYPE_NONE;
 		meta->gso_size = 0;
+	}
 
 	meta->size = 0;
 	meta->id = req->id;
@@ -592,7 +615,8 @@ void xenvif_rx_action(struct xenvif *vif)
 
 		vif = netdev_priv(skb->dev);
 
-		if (vif->meta[npo.meta_cons].gso_size && vif->gso_prefix) {
+		if ((1 << vif->meta[npo.meta_cons].gso_type) &
+		    vif->gso_prefix_mask) {
 			resp = RING_GET_RESPONSE(&vif->rx,
 						 vif->rx.rsp_prod_pvt++);
 
@@ -629,7 +653,8 @@ void xenvif_rx_action(struct xenvif *vif)
 					vif->meta[npo.meta_cons].size,
 					flags);
 
-		if (vif->meta[npo.meta_cons].gso_size && !vif->gso_prefix) {
+		if ((1 << vif->meta[npo.meta_cons].gso_type) &
+		    vif->gso_mask) {
 			struct xen_netif_extra_info *gso =
 				(struct xen_netif_extra_info *)
 				RING_GET_RESPONSE(&vif->rx,
@@ -637,8 +662,8 @@ void xenvif_rx_action(struct xenvif *vif)
 
 			resp->flags |= XEN_NETRXF_extra_info;
 
+			gso->u.gso.type = vif->meta[npo.meta_cons].gso_type;
 			gso->u.gso.size = vif->meta[npo.meta_cons].gso_size;
-			gso->u.gso.type = XEN_NETIF_GSO_TYPE_TCPV4;
 			gso->u.gso.pad = 0;
 			gso->u.gso.features = 0;
 
@@ -1101,15 +1126,20 @@ static int xenvif_set_skb_gso(struct xenvif *vif,
 		return -EINVAL;
 	}
 
-	/* Currently only TCPv4 S.O. is supported. */
-	if (gso->u.gso.type != XEN_NETIF_GSO_TYPE_TCPV4) {
+	switch (gso->u.gso.type) {
+	case XEN_NETIF_GSO_TYPE_TCPV4:
+		skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
+		break;
+	case XEN_NETIF_GSO_TYPE_TCPV6:
+		skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
+		break;
+	default:
 		netdev_err(vif->dev, "Bad GSO type %d.\n", gso->u.gso.type);
 		xenvif_fatal_tx_err(vif);
 		return -EINVAL;
 	}
 
 	skb_shinfo(skb)->gso_size = gso->u.gso.size;
-	skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
 
 	/* Header must be checked, and gso_segs computed. */
 	skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
@@ -1118,61 +1148,74 @@ static int xenvif_set_skb_gso(struct xenvif *vif,
 	return 0;
 }
 
-static int checksum_setup(struct xenvif *vif, struct sk_buff *skb)
+static inline void maybe_pull_tail(struct sk_buff *skb, unsigned int len)
+{
+	if (skb_is_nonlinear(skb) && skb_headlen(skb) < len) {
+		/* If we need to pullup then pullup to the max, so we
+		 * won't need to do it again.
+		 */
+		int target = min_t(int, skb->len, MAX_TCP_HEADER);
+		__pskb_pull_tail(skb, target - skb_headlen(skb));
+	}
+}
+
+static int checksum_setup_ip(struct xenvif *vif, struct sk_buff *skb,
+			     int recalculate_partial_csum)
 {
-	struct iphdr *iph;
+	struct iphdr *iph = (void *)skb->data;
+	unsigned int header_size;
+	unsigned int off;
 	int err = -EPROTO;
-	int recalculate_partial_csum = 0;
 
-	/*
-	 * A GSO SKB must be CHECKSUM_PARTIAL. However some buggy
-	 * peers can fail to set NETRXF_csum_blank when sending a GSO
-	 * frame. In this case force the SKB to CHECKSUM_PARTIAL and
-	 * recalculate the partial checksum.
-	 */
-	if (skb->ip_summed != CHECKSUM_PARTIAL && skb_is_gso(skb)) {
-		vif->rx_gso_checksum_fixup++;
-		skb->ip_summed = CHECKSUM_PARTIAL;
-		recalculate_partial_csum = 1;
-	}
+	off = sizeof(struct iphdr);
 
-	/* A non-CHECKSUM_PARTIAL SKB does not require setup. */
-	if (skb->ip_summed != CHECKSUM_PARTIAL)
-		return 0;
+	header_size = skb->network_header + off + MAX_IPOPTLEN;
+	maybe_pull_tail(skb, header_size);
 
-	if (skb->protocol != htons(ETH_P_IP))
-		goto out;
+	off = iph->ihl * 4;
 
-	iph = (void *)skb->data;
 	switch (iph->protocol) {
 	case IPPROTO_TCP:
-		if (!skb_partial_csum_set(skb, 4 * iph->ihl,
+		if (!skb_partial_csum_set(skb, off,
 					  offsetof(struct tcphdr, check)))
 			goto out;
 
 		if (recalculate_partial_csum) {
 			struct tcphdr *tcph = tcp_hdr(skb);
+
+			header_size = skb->network_header +
+				off +
+				sizeof(struct tcphdr);
+			maybe_pull_tail(skb, header_size);
+
 			tcph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
-							 skb->len - iph->ihl*4,
+							 skb->len - off,
 							 IPPROTO_TCP, 0);
 		}
 		break;
 	case IPPROTO_UDP:
-		if (!skb_partial_csum_set(skb, 4 * iph->ihl,
+		if (!skb_partial_csum_set(skb, off,
 					  offsetof(struct udphdr, check)))
 			goto out;
 
 		if (recalculate_partial_csum) {
 			struct udphdr *udph = udp_hdr(skb);
+
+			header_size = skb->network_header +
+				off +
+				sizeof(struct udphdr);
+			maybe_pull_tail(skb, header_size);
+
 			udph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
-							 skb->len - iph->ihl*4,
+							 skb->len - off,
 							 IPPROTO_UDP, 0);
 		}
 		break;
 	default:
 		if (net_ratelimit())
 			netdev_err(vif->dev,
-				   "Attempting to checksum a non-TCP/UDP packet, dropping a protocol %d packet\n",
+				   "Attempting to checksum a non-TCP/UDP packet, "
+				   "dropping a protocol %d packet\n",
 				   iph->protocol);
 		goto out;
 	}
@@ -1183,6 +1226,158 @@ out:
 	return err;
 }
 
+static int checksum_setup_ipv6(struct xenvif *vif, struct sk_buff *skb,
+			       int recalculate_partial_csum)
+{
+	int err = -EPROTO;
+	struct ipv6hdr *ipv6h = (void *)skb->data;
+	u8 nexthdr;
+	unsigned int header_size;
+	unsigned int off;
+	bool fragment;
+	bool done;
+
+	done = false;
+
+	off = sizeof(struct ipv6hdr);
+
+	header_size = skb->network_header + off;
+	maybe_pull_tail(skb, header_size);
+
+	nexthdr = ipv6h->nexthdr;
+
+	while ((off <= sizeof(struct ipv6hdr) + ntohs(ipv6h->payload_len)) &&
+	       !done) {
+		switch (nexthdr) {
+		case IPPROTO_DSTOPTS:
+		case IPPROTO_HOPOPTS:
+		case IPPROTO_ROUTING: {
+			struct ipv6_opt_hdr *hp = (void *)(skb->data + off);
+
+			header_size = skb->network_header +
+				off +
+				sizeof(struct ipv6_opt_hdr);
+			maybe_pull_tail(skb, header_size);
+
+			nexthdr = hp->nexthdr;
+			off += ipv6_optlen(hp);
+			break;
+		}
+		case IPPROTO_AH: {
+			struct ip_auth_hdr *hp = (void *)(skb->data + off);
+
+			header_size = skb->network_header +
+				off +
+				sizeof(struct ip_auth_hdr);
+			maybe_pull_tail(skb, header_size);
+
+			nexthdr = hp->nexthdr;
+			off += (hp->hdrlen+2)<<2;
+			break;
+		}
+		case IPPROTO_FRAGMENT:
+			fragment = true;
+			/* fall through */
+		default:
+			done = true;
+			break;
+		}
+	}
+
+	if (!done) {
+		if (net_ratelimit())
+			netdev_err(vif->dev, "Failed to parse packet header\n");
+		goto out;
+	}
+
+	if (fragment) {
+		if (net_ratelimit())
+			netdev_err(vif->dev, "Packet is a fragment!\n");
+		goto out;
+	}
+
+	switch (nexthdr) {
+	case IPPROTO_TCP:
+		if (!skb_partial_csum_set(skb, off,
+					  offsetof(struct tcphdr, check)))
+			goto out;
+
+		if (recalculate_partial_csum) {
+			struct tcphdr *tcph = tcp_hdr(skb);
+
+			header_size = skb->network_header +
+				off +
+				sizeof(struct tcphdr);
+			maybe_pull_tail(skb, header_size);
+
+			tcph->check = ~csum_ipv6_magic(&ipv6h->saddr,
+						       &ipv6h->daddr,
+						       skb->len - off,
+						       IPPROTO_TCP, 0);
+		}
+		break;
+	case IPPROTO_UDP:
+		if (!skb_partial_csum_set(skb, off,
+					  offsetof(struct udphdr, check)))
+			goto out;
+
+		if (recalculate_partial_csum) {
+			struct udphdr *udph = udp_hdr(skb);
+
+			header_size = skb->network_header +
+				off +
+				sizeof(struct udphdr);
+			maybe_pull_tail(skb, header_size);
+
+			udph->check = ~csum_ipv6_magic(&ipv6h->saddr,
+						       &ipv6h->daddr,
+						       skb->len - off,
+						       IPPROTO_UDP, 0);
+		}
+		break;
+	default:
+		if (net_ratelimit())
+			netdev_err(vif->dev,
+				   "Attempting to checksum a non-TCP/UDP packet, "
+				   "dropping a protocol %d packet\n",
+				   nexthdr);
+		goto out;
+	}
+
+	err = 0;
+
+out:
+	return err;
+}
+
+static int checksum_setup(struct xenvif *vif, struct sk_buff *skb)
+{
+	int err = -EPROTO;
+	int recalculate_partial_csum = 0;
+
+	/* A GSO SKB must be CHECKSUM_PARTIAL. However some buggy
+	 * peers can fail to set NETRXF_csum_blank when sending a GSO
+	 * frame. In this case force the SKB to CHECKSUM_PARTIAL and
+	 * recalculate the partial checksum.
+	 */
+	if (skb->ip_summed != CHECKSUM_PARTIAL && skb_is_gso(skb)) {
+		vif->rx_gso_checksum_fixup++;
+		skb->ip_summed = CHECKSUM_PARTIAL;
+		recalculate_partial_csum = 1;
+	}
+
+	/* A non-CHECKSUM_PARTIAL SKB does not require setup. */
+	if (skb->ip_summed != CHECKSUM_PARTIAL)
+		return 0;
+
+	if (skb->protocol == htons(ETH_P_IP))
+		err = checksum_setup_ip(vif, skb, recalculate_partial_csum);
+	else if (skb->protocol == htons(ETH_P_IPV6))
+		err = checksum_setup_ipv6(vif, skb, recalculate_partial_csum);
+
+	return err;
+}
+
 static bool tx_credit_exceeded(struct xenvif *vif, unsigned size)
 {
 	u64 now = get_jiffies_64();
@@ -1428,12 +1623,7 @@ static int xenvif_tx_submit(struct xenvif *vif, int budget)
 
 		xenvif_fill_frags(vif, skb);
 
-		/*
-		 * If the initial fragment was < PKT_PROT_LEN then
-		 * pull through some bytes from the other fragments to
-		 * increase the linear region to PKT_PROT_LEN bytes.
-		 */
-		if (skb_headlen(skb) < PKT_PROT_LEN && skb_is_nonlinear(skb)) {
+		if (skb_is_nonlinear(skb) && skb_headlen(skb) < PKT_PROT_LEN) {
 			int target = min_t(int, skb->len, PKT_PROT_LEN);
 			__pskb_pull_tail(skb, target - skb_headlen(skb));
 		}
diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 1b08d879837..f0358992b04 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -105,6 +105,22 @@ static int netback_probe(struct xenbus_device *dev,
 			goto abort_transaction;
 		}
 
+		err = xenbus_printf(xbt, dev->nodename, "feature-gso-tcpv6",
+				    "%d", sg);
+		if (err) {
+			message = "writing feature-gso-tcpv6";
+			goto abort_transaction;
+		}
+
+		/* We support partial checksum setup for IPv6 packets */
+		err = xenbus_printf(xbt, dev->nodename,
+				    "feature-ipv6-csum-offload",
+				    "%d", 1);
+		if (err) {
+			message = "writing feature-ipv6-csum-offload";
+			goto abort_transaction;
+		}
+
 		/* We support rx-copy path. */
 		err = xenbus_printf(xbt, dev->nodename,
 				    "feature-rx-copy", "%d", 1);
@@ -561,20 +577,50 @@ static int connect_rings(struct backend_info *be)
 		val = 0;
 	vif->can_sg = !!val;
 
+	vif->gso_mask = 0;
+	vif->gso_prefix_mask = 0;
+
 	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4",
 			 "%d", &val) < 0)
 		val = 0;
-	vif->gso = !!val;
+	if (val)
+		vif->gso_mask |= GSO_BIT(TCPV4);
 
 	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4-prefix",
 			 "%d", &val) < 0)
 		val = 0;
-	vif->gso_prefix = !!val;
+	if (val)
+		vif->gso_prefix_mask |= GSO_BIT(TCPV4);
+
+	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv6",
+			 "%d", &val) < 0)
+		val = 0;
+	if (val)
+		vif->gso_mask |= GSO_BIT(TCPV6);
+
+	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv6-prefix",
+			 "%d", &val) < 0)
+		val = 0;
+	if (val)
+		vif->gso_prefix_mask |= GSO_BIT(TCPV6);
+
+	if (vif->gso_mask & vif->gso_prefix_mask) {
+		xenbus_dev_fatal(dev, err,
+				 "%s: gso and gso prefix flags are not "
+				 "mutually exclusive",
+				 dev->otherend);
+		return -EOPNOTSUPP;
+	}
 
 	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-no-csum-offload",
 			 "%d", &val) < 0)
 		val = 0;
-	vif->csum = !val;
+	vif->ip_csum = !val;
+
+	if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-ipv6-csum-offload",
+			 "%d", &val) < 0)
+		val = 0;
+	vif->ipv6_csum = !!val;
 
 	/* Map the shared frame, irq etc. */
 	err = xenvif_connect(vif, tx_ring_ref, rx_ring_ref,