Merge branch 'netvsc-transparent-VF-support'

Stephen Hemminger says:

====================
netvsc: transparent VF support

This patch set changes how SR-IOV Virtual Function devices are managed
in the Hyper-V network driver. This version is rebased onto current net-next.

Background

In Hyper-V SR-IOV can be enabled (and disabled) by changing guest settings
on host. When SR-IOV is enabled a matching PCI device is hot plugged and
visible on guest. The VF device is an add-on to an existing netvsc
device, and has the same MAC address.

How is this different?

The original support of VF relied on using bonding driver in active
standby mode to handle the VF device.

With the new netvsc VF logic, the Linux hyper-V network
virtual driver will directly manage the link to SR-IOV VF device.
When VF device is detected (hot plug) it is automatically made a
slave device of the netvsc device. The VF device state reflects
the state of the netvsc device; i.e. if netvsc is set down, then
VF is set down. If netvsc is set up, then VF is brought up.

Packet flow is independent of VF status; all packets are sent and
received as if they were associated with the netvsc device. If VF is
removed or link is down then the synthetic VMBUS path is used.

What was wrong with using bonding script?

A lot of work went into getting the bonding script to work on all
distributions, but it was a major struggle. Linux network devices
can be configured many, many ways and there is no one solution from
userspace to make it all work. What is really hard is when
configuration is attached to synthetic device during boot (eth0) and
then the same addresses and firewall rules needs to also work later if
doing bonding. The new code gets around all of this.

How does VF work during initialization?

Since all packets are sent and received through the logical netvsc
device, initialization is much easier. Just configure the regular
netvsc Ethernet device; when/if SR-IOV is enabled it just
works. Provisioning and cloud init only need to worry about setting up
netvsc device (eth0). If SR-IOV is enabled (even as a later step), the
address and rules stay the same.

What devices show up?

Both netvsc and PCI devices are visible in the system. The netvsc
device is active and named in usual manner (eth0). The PCI device is
visible to Linux and gets renamed by udev to a persistent name
(enP2p3s0). The PCI device name is now irrelevant now.

The logic also sets the PCI VF device SLAVE flag on the network
device so network tools can see the relationship if they are smart
enough to understand how layered devices work.

This is a lot like how I see Windows working.
The VF device is visible in Device Manager, but is not configured.

Is there any performance impact?
There is no visible change in performance. The bonding
and netvsc driver both have equivalent steps.

Is it compatible with old bonding script?

It turns out that if you use the old bonding script, then everything
still works but in a sub-optimum manner. What happens is that bonding
is unable to steal the VF from the netvsc device so it creates a one
legged bond.  Packet flow then is:
	bond0 <--> eth0 <- -> VF (enP2p3s0).
In other words, if you get it wrong it still works, just
awkward and slower.

What if I add address or firewall rule onto the VF?

Same problems occur with now as already occur with bonding, bridging,
teaming on Linux if user incorrectly does configuration onto
an underlying slave device. It will sort of work, packets will come in
and out but the Linux kernel gets confused and things like ARP don’t
work right.  There is no way to block manipulation of the slave
device, and I am sure someone will find some special use case where
they want it.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/netvsc.txt

+Hyper-V network driver
+======================
+
+Compatibility
+=============
+
+This driver is compatible with Windows Server 2012 R2, 2016 and
+Windows 10.
+
+Features
+========
+
+  Checksum offload
+  ----------------
+  The netvsc driver supports checksum offload as long as the
+  Hyper-V host version does. Windows Server 2016 and Azure
+  support checksum offload for TCP and UDP for both IPv4 and
+  IPv6. Windows Server 2012 only supports checksum offload for TCP.
+
+  Receive Side Scaling
+  --------------------
+  Hyper-V supports receive side scaling. For TCP, packets are
+  distributed among available queues based on IP address and port
+  number. Current versions of Hyper-V host, only distribute UDP
+  packets based on the IP source and destination address.
+  The port number is not used as part of the hash value for UDP.
+  Fragmented IP packets are not distributed between queues;
+  all fragmented packets arrive on the first channel.
+
+  Generic Receive Offload, aka GRO
+  --------------------------------
+  The driver supports GRO and it is enabled by default. GRO coalesces
+  like packets and significantly reduces CPU usage under heavy Rx
+  load.
+
+  SR-IOV support
+  --------------
+  Hyper-V supports SR-IOV as a hardware acceleration option. If SR-IOV
+  is enabled in both the vSwitch and the guest configuration, then the
+  Virtual Function (VF) device is passed to the guest as a PCI
+  device. In this case, both a synthetic (netvsc) and VF device are
+  visible in the guest OS and both NIC's have the same MAC address.
+
+  The VF is enslaved by netvsc device.  The netvsc driver will transparently
+  switch the data path to the VF when it is available and up.
+  Network state (addresses, firewall, etc) should be applied only to the
+  netvsc device; the slave device should not be accessed directly in
+  most cases.  The exceptions are if some special queue discipline or
+  flow direction is desired, these should be applied directly to the
+  VF slave device.
+
+  Receive Buffer
+  --------------
+  Packets are received into a receive area which is created when device
+  is probed. The receive area is broken into MTU sized chunks and each may
+  contain one or more packets. The number of receive sections may be changed
+  via ethtool Rx ring parameters.
+
+  There is a similar send buffer which is used to aggregate packets for sending.
+  The send area is broken into chunks of 6144 bytes, each of section may
+  contain one or more packets. The send buffer is an optimization, the driver
+  will use slower method to handle very large packets or if the send buffer
+  area is exhausted.

MAINTAINERS

@@ -6258,6 +6258,7 @@ M:	Haiyang Zhang <haiyangz@microsoft.com>
 M:	Stephen Hemminger <sthemmin@microsoft.com>
 L:	devel@linuxdriverproject.org
 S:	Maintained
+F:	Documentation/networking/netvsc.txt
 F:	arch/x86/include/asm/mshyperv.h
 F:	arch/x86/include/uapi/asm/hyperv.h
 F:	arch/x86/kernel/cpu/mshyperv.c

drivers/net/hyperv/hyperv_net.h

@@ -680,6 +680,15 @@ struct netvsc_ethtool_stats {
 	unsigned long tx_busy;
 };
 
+struct netvsc_vf_pcpu_stats {
+	u64     rx_packets;
+	u64     rx_bytes;
+	u64     tx_packets;
+	u64     tx_bytes;
+	struct u64_stats_sync   syncp;
+	u32	tx_dropped;
+};
+
 struct netvsc_reconfig {
 	struct list_head list;
 	u32 event;
@@ -713,6 +722,9 @@ struct net_device_context {
 
 	/* State to manage the associated VF interface. */
 	struct net_device __rcu *vf_netdev;
+	struct netvsc_vf_pcpu_stats __percpu *vf_stats;
+	struct work_struct vf_takeover;
+	struct work_struct vf_notify;
 
 	/* 1: allocated, serial number is valid. 0: not allocated */
 	u32 vf_alloc;

drivers/net/hyperv/netvsc_drv.c

@@ -34,6 +34,7 @@
 #include <linux/in.h>
 #include <linux/slab.h>
 #include <linux/rtnetlink.h>
+#include <linux/netpoll.h>
 
 #include <net/arp.h>
 #include <net/route.h>
@@ -71,6 +72,7 @@ static void netvsc_set_multicast_list(struct net_device *net)
 static int netvsc_open(struct net_device *net)
 {
 	struct net_device_context *ndev_ctx = netdev_priv(net);
+	struct net_device *vf_netdev = rtnl_dereference(ndev_ctx->vf_netdev);
 	struct netvsc_device *nvdev = rtnl_dereference(ndev_ctx->nvdev);
 	struct rndis_device *rdev;
 	int ret = 0;
@@ -87,15 +89,29 @@ static int netvsc_open(struct net_device *net)
 	netif_tx_wake_all_queues(net);
 
 	rdev = nvdev->extension;
-	if (!rdev->link_state && !ndev_ctx->datapath)
+
+	if (!rdev->link_state)
 		netif_carrier_on(net);
 
-	return ret;
+	if (vf_netdev) {
+		/* Setting synthetic device up transparently sets
+		 * slave as up. If open fails, then slave will be
+		 * still be offline (and not used).
+		 */
+		ret = dev_open(vf_netdev);
+		if (ret)
+			netdev_warn(net,
+				    "unable to open slave: %s: %d\n",
+				    vf_netdev->name, ret);
+	}
+	return 0;
 }
 
 static int netvsc_close(struct net_device *net)
 {
 	struct net_device_context *net_device_ctx = netdev_priv(net);
+	struct net_device *vf_netdev
+		= rtnl_dereference(net_device_ctx->vf_netdev);
 	struct netvsc_device *nvdev = rtnl_dereference(net_device_ctx->nvdev);
 	int ret;
 	u32 aread, i, msec = 10, retry = 0, retry_max = 20;
@@ -141,6 +157,9 @@ static int netvsc_close(struct net_device *net)
 		ret = -ETIMEDOUT;
 	}
 
+	if (vf_netdev)
+		dev_close(vf_netdev);
+
 	return ret;
 }
 
@@ -224,13 +243,11 @@ static inline int netvsc_get_tx_queue(struct net_device *ndev,
  *
  * TODO support XPS - but get_xps_queue not exported
  */
-static u16 netvsc_select_queue(struct net_device *ndev, struct sk_buff *skb,
-			void *accel_priv, select_queue_fallback_t fallback)
+static u16 netvsc_pick_tx(struct net_device *ndev, struct sk_buff *skb)
 {
-	unsigned int num_tx_queues = ndev->real_num_tx_queues;
 	int q_idx = sk_tx_queue_get(skb->sk);
 
-	if (q_idx < 0 || skb->ooo_okay) {
+	if (q_idx < 0 || skb->ooo_okay || q_idx >= ndev->real_num_tx_queues) {
 		/* If forwarding a packet, we use the recorded queue when
 		 * available for better cache locality.
 		 */
@@ -240,12 +257,33 @@ static u16 netvsc_select_queue(struct net_device *ndev, struct sk_buff *skb,
 			q_idx = netvsc_get_tx_queue(ndev, skb, q_idx);
 	}
 
-	while (unlikely(q_idx >= num_tx_queues))
-		q_idx -= num_tx_queues;
-
 	return q_idx;
 }
 
+static u16 netvsc_select_queue(struct net_device *ndev, struct sk_buff *skb,
+			       void *accel_priv,
+			       select_queue_fallback_t fallback)
+{
+	struct net_device_context *ndc = netdev_priv(ndev);
+	struct net_device *vf_netdev;
+	u16 txq;
+
+	rcu_read_lock();
+	vf_netdev = rcu_dereference(ndc->vf_netdev);
+	if (vf_netdev) {
+		txq = skb_rx_queue_recorded(skb) ? skb_get_rx_queue(skb) : 0;
+		qdisc_skb_cb(skb)->slave_dev_queue_mapping = skb->queue_mapping;
+	} else {
+		txq = netvsc_pick_tx(ndev, skb);
+	}
+	rcu_read_unlock();
+
+	while (unlikely(txq >= ndev->real_num_tx_queues))
+		txq -= ndev->real_num_tx_queues;
+
+	return txq;
+}
+
 static u32 fill_pg_buf(struct page *page, u32 offset, u32 len,
 			struct hv_page_buffer *pb)
 {
@@ -367,6 +405,33 @@ static u32 net_checksum_info(struct sk_buff *skb)
 	return TRANSPORT_INFO_NOT_IP;
 }
 
+/* Send skb on the slave VF device. */
+static int netvsc_vf_xmit(struct net_device *net, struct net_device *vf_netdev,
+			  struct sk_buff *skb)
+{
+	struct net_device_context *ndev_ctx = netdev_priv(net);
+	unsigned int len = skb->len;
+	int rc;
+
+	skb->dev = vf_netdev;
+	skb->queue_mapping = qdisc_skb_cb(skb)->slave_dev_queue_mapping;
+
+	rc = dev_queue_xmit(skb);
+	if (likely(rc == NET_XMIT_SUCCESS || rc == NET_XMIT_CN)) {
+		struct netvsc_vf_pcpu_stats *pcpu_stats
+			= this_cpu_ptr(ndev_ctx->vf_stats);
+
+		u64_stats_update_begin(&pcpu_stats->syncp);
+		pcpu_stats->tx_packets++;
+		pcpu_stats->tx_bytes += len;
+		u64_stats_update_end(&pcpu_stats->syncp);
+	} else {
+		this_cpu_inc(ndev_ctx->vf_stats->tx_dropped);
+	}
+
+	return rc;
+}
+
 static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
 {
 	struct net_device_context *net_device_ctx = netdev_priv(net);
@@ -375,11 +440,20 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
 	unsigned int num_data_pgs;
 	struct rndis_message *rndis_msg;
 	struct rndis_packet *rndis_pkt;
+	struct net_device *vf_netdev;
 	u32 rndis_msg_size;
 	struct rndis_per_packet_info *ppi;
 	u32 hash;
 	struct hv_page_buffer pb[MAX_PAGE_BUFFER_COUNT];
 
+	/* if VF is present and up then redirect packets
+	 * already called with rcu_read_lock_bh
+	 */
+	vf_netdev = rcu_dereference_bh(net_device_ctx->vf_netdev);
+	if (vf_netdev && netif_running(vf_netdev) &&
+	    !netpoll_tx_running(net))
+		return netvsc_vf_xmit(net, vf_netdev, skb);
+
 	/* We will atmost need two pages to describe the rndis
 	 * header. We can only transmit MAX_PAGE_BUFFER_COUNT number
 	 * of pages in a single packet. If skb is scattered around
@@ -658,29 +732,18 @@ int netvsc_recv_callback(struct net_device *net,
 	struct netvsc_device *net_device;
 	u16 q_idx = channel->offermsg.offer.sub_channel_index;
 	struct netvsc_channel *nvchan;
-	struct net_device *vf_netdev;
 	struct sk_buff *skb;
 	struct netvsc_stats *rx_stats;
 
 	if (net->reg_state != NETREG_REGISTERED)
 		return NVSP_STAT_FAIL;
 
-	/*
-	 * If necessary, inject this packet into the VF interface.
-	 * On Hyper-V, multicast and brodcast packets are only delivered
-	 * to the synthetic interface (after subjecting these to
-	 * policy filters on the host). Deliver these via the VF
-	 * interface in the guest.
-	 */
 	rcu_read_lock();
 	net_device = rcu_dereference(net_device_ctx->nvdev);
 	if (unlikely(!net_device))
 		goto drop;
 
 	nvchan = &net_device->chan_table[q_idx];
-	vf_netdev = rcu_dereference(net_device_ctx->vf_netdev);
-	if (vf_netdev && (vf_netdev->flags & IFF_UP))
-		net = vf_netdev;
 
 	/* Allocate a skb - TODO direct I/O to pages? */
 	skb = netvsc_alloc_recv_skb(net, &nvchan->napi,
@@ -692,8 +755,7 @@ int netvsc_recv_callback(struct net_device *net,
 		return NVSP_STAT_FAIL;
 	}
 
-	if (net != vf_netdev)
-		skb_record_rx_queue(skb, q_idx);
+	skb_record_rx_queue(skb, q_idx);
 
 	/*
 	 * Even if injecting the packet, record the statistics
@@ -853,6 +915,7 @@ static int netvsc_set_link_ksettings(struct net_device *dev,
 static int netvsc_change_mtu(struct net_device *ndev, int mtu)
 {
 	struct net_device_context *ndevctx = netdev_priv(ndev);
+	struct net_device *vf_netdev = rtnl_dereference(ndevctx->vf_netdev);
 	struct netvsc_device *nvdev = rtnl_dereference(ndevctx->nvdev);
 	struct hv_device *hdev = ndevctx->device_ctx;
 	int orig_mtu = ndev->mtu;
@@ -863,6 +926,13 @@ static int netvsc_change_mtu(struct net_device *ndev, int mtu)
 	if (!nvdev || nvdev->destroy)
 		return -ENODEV;
 
+	/* Change MTU of underlying VF netdev first. */
+	if (vf_netdev) {
+		ret = dev_set_mtu(vf_netdev, mtu);
+		if (ret)
+			return ret;
+	}
+
 	netif_device_detach(ndev);
 	was_opened = rndis_filter_opened(nvdev);
 	if (was_opened)
@@ -883,6 +953,9 @@ static int netvsc_change_mtu(struct net_device *ndev, int mtu)
 		/* Attempt rollback to original MTU */
 		ndev->mtu = orig_mtu;
 		rndis_filter_device_add(hdev, &device_info);
+
+		if (vf_netdev)
+			dev_set_mtu(vf_netdev, orig_mtu);
 	}
 
 	if (was_opened)
@@ -896,16 +969,56 @@ static int netvsc_change_mtu(struct net_device *ndev, int mtu)
 	return ret;
 }
 
+static void netvsc_get_vf_stats(struct net_device *net,
+				struct netvsc_vf_pcpu_stats *tot)
+{
+	struct net_device_context *ndev_ctx = netdev_priv(net);
+	int i;
+
+	memset(tot, 0, sizeof(*tot));
+
+	for_each_possible_cpu(i) {
+		const struct netvsc_vf_pcpu_stats *stats
+			= per_cpu_ptr(ndev_ctx->vf_stats, i);
+		u64 rx_packets, rx_bytes, tx_packets, tx_bytes;
+		unsigned int start;
+
+		do {
+			start = u64_stats_fetch_begin_irq(&stats->syncp);
+			rx_packets = stats->rx_packets;
+			tx_packets = stats->tx_packets;
+			rx_bytes = stats->rx_bytes;
+			tx_bytes = stats->tx_bytes;
+		} while (u64_stats_fetch_retry_irq(&stats->syncp, start));
+
+		tot->rx_packets += rx_packets;
+		tot->tx_packets += tx_packets;
+		tot->rx_bytes   += rx_bytes;
+		tot->tx_bytes   += tx_bytes;
+		tot->tx_dropped += stats->tx_dropped;
+	}
+}
+
 static void netvsc_get_stats64(struct net_device *net,
 			       struct rtnl_link_stats64 *t)
 {
 	struct net_device_context *ndev_ctx = netdev_priv(net);
 	struct netvsc_device *nvdev = rcu_dereference_rtnl(ndev_ctx->nvdev);
-	int i;
+	struct netvsc_vf_pcpu_stats vf_tot;
+		int i;
 
 	if (!nvdev)
 		return;
 
+	netdev_stats_to_stats64(t, &net->stats);
+
+	netvsc_get_vf_stats(net, &vf_tot);
+	t->rx_packets += vf_tot.rx_packets;
+	t->tx_packets += vf_tot.tx_packets;
+	t->rx_bytes   += vf_tot.rx_bytes;
+	t->tx_bytes   += vf_tot.tx_bytes;
+	t->tx_dropped += vf_tot.tx_dropped;
+
 	for (i = 0; i < nvdev->num_chn; i++) {
 		const struct netvsc_channel *nvchan = &nvdev->chan_table[i];
 		const struct netvsc_stats *stats;
@@ -934,12 +1047,6 @@ static void netvsc_get_stats64(struct net_device *net,
 		t->rx_packets	+= packets;
 		t->multicast	+= multicast;
 	}
-
-	t->tx_dropped	= net->stats.tx_dropped;
-	t->tx_errors	= net->stats.tx_errors;
-
-	t->rx_dropped	= net->stats.rx_dropped;
-	t->rx_errors	= net->stats.rx_errors;
 }
 
 static int netvsc_set_mac_addr(struct net_device *ndev, void *p)
@@ -980,9 +1087,16 @@ static const struct {
 	{ "tx_no_space",  offsetof(struct netvsc_ethtool_stats, tx_no_space) },
 	{ "tx_too_big",	  offsetof(struct netvsc_ethtool_stats, tx_too_big) },
 	{ "tx_busy",	  offsetof(struct netvsc_ethtool_stats, tx_busy) },
+}, vf_stats[] = {
+	{ "vf_rx_packets", offsetof(struct netvsc_vf_pcpu_stats, rx_packets) },
+	{ "vf_rx_bytes",   offsetof(struct netvsc_vf_pcpu_stats, rx_bytes) },
+	{ "vf_tx_packets", offsetof(struct netvsc_vf_pcpu_stats, tx_packets) },
+	{ "vf_tx_bytes",   offsetof(struct netvsc_vf_pcpu_stats, tx_bytes) },
+	{ "vf_tx_dropped", offsetof(struct netvsc_vf_pcpu_stats, tx_dropped) },
 };
 
 #define NETVSC_GLOBAL_STATS_LEN	ARRAY_SIZE(netvsc_stats)
+#define NETVSC_VF_STATS_LEN	ARRAY_SIZE(vf_stats)
 
 /* 4 statistics per queue (rx/tx packets/bytes) */
 #define NETVSC_QUEUE_STATS_LEN(dev) ((dev)->num_chn * 4)
@@ -997,7 +1111,9 @@ static int netvsc_get_sset_count(struct net_device *dev, int string_set)
 
 	switch (string_set) {
 	case ETH_SS_STATS:
-		return NETVSC_GLOBAL_STATS_LEN + NETVSC_QUEUE_STATS_LEN(nvdev);
+		return NETVSC_GLOBAL_STATS_LEN
+			+ NETVSC_VF_STATS_LEN
+			+ NETVSC_QUEUE_STATS_LEN(nvdev);
 	default:
 		return -EINVAL;
 	}
@@ -1010,6 +1126,7 @@ static void netvsc_get_ethtool_stats(struct net_device *dev,
 	struct netvsc_device *nvdev = rtnl_dereference(ndc->nvdev);
 	const void *nds = &ndc->eth_stats;
 	const struct netvsc_stats *qstats;
+	struct netvsc_vf_pcpu_stats sum;
 	unsigned int start;
 	u64 packets, bytes;
 	int i, j;
@@ -1020,6 +1137,10 @@ static void netvsc_get_ethtool_stats(struct net_device *dev,
 	for (i = 0; i < NETVSC_GLOBAL_STATS_LEN; i++)
 		data[i] = *(unsigned long *)(nds + netvsc_stats[i].offset);
 
+	netvsc_get_vf_stats(dev, &sum);
+	for (j = 0; j < NETVSC_VF_STATS_LEN; j++)
+		data[i++] = *(u64 *)((void *)&sum + vf_stats[j].offset);
+
 	for (j = 0; j < nvdev->num_chn; j++) {
 		qstats = &nvdev->chan_table[j].tx_stats;
 
@@ -1054,11 +1175,16 @@ static void netvsc_get_strings(struct net_device *dev, u32 stringset, u8 *data)
 
 	switch (stringset) {
 	case ETH_SS_STATS:
-		for (i = 0; i < ARRAY_SIZE(netvsc_stats); i++)
-			memcpy(p + i * ETH_GSTRING_LEN,
-			       netvsc_stats[i].name, ETH_GSTRING_LEN);
+		for (i = 0; i < ARRAY_SIZE(netvsc_stats); i++) {
+			memcpy(p, netvsc_stats[i].name, ETH_GSTRING_LEN);
+			p += ETH_GSTRING_LEN;
+		}
+
+		for (i = 0; i < ARRAY_SIZE(vf_stats); i++) {
+			memcpy(p, vf_stats[i].name, ETH_GSTRING_LEN);
+			p += ETH_GSTRING_LEN;
+		}
 
-		p += i * ETH_GSTRING_LEN;
 		for (i = 0; i < nvdev->num_chn; i++) {
 			sprintf(p, "tx_queue_%u_packets", i);
 			p += ETH_GSTRING_LEN;
@@ -1298,8 +1424,7 @@ static void netvsc_link_change(struct work_struct *w)
 	case RNDIS_STATUS_MEDIA_CONNECT:
 		if (rdev->link_state) {
 			rdev->link_state = false;
-			if (!ndev_ctx->datapath)
-				netif_carrier_on(net);
+			netif_carrier_on(net);
 			netif_tx_wake_all_queues(net);
 		} else {
 			notify = true;
@@ -1386,6 +1511,104 @@ static struct net_device *get_netvsc_byref(struct net_device *vf_netdev)
 	return NULL;
 }
 
+/* Called when VF is injecting data into network stack.
+ * Change the associated network device from VF to netvsc.
+ * note: already called with rcu_read_lock
+ */
+static rx_handler_result_t netvsc_vf_handle_frame(struct sk_buff **pskb)
+{
+	struct sk_buff *skb = *pskb;
+	struct net_device *ndev = rcu_dereference(skb->dev->rx_handler_data);
+	struct net_device_context *ndev_ctx = netdev_priv(ndev);
+	struct netvsc_vf_pcpu_stats *pcpu_stats
+		 = this_cpu_ptr(ndev_ctx->vf_stats);
+
+	skb->dev = ndev;
+
+	u64_stats_update_begin(&pcpu_stats->syncp);
+	pcpu_stats->rx_packets++;
+	pcpu_stats->rx_bytes += skb->len;
+	u64_stats_update_end(&pcpu_stats->syncp);
+
+	return RX_HANDLER_ANOTHER;
+}
+
+static int netvsc_vf_join(struct net_device *vf_netdev,
+			  struct net_device *ndev)
+{
+	struct net_device_context *ndev_ctx = netdev_priv(ndev);
+	int ret;
+
+	ret = netdev_rx_handler_register(vf_netdev,
+					 netvsc_vf_handle_frame, ndev);
+	if (ret != 0) {
+		netdev_err(vf_netdev,
+			   "can not register netvsc VF receive handler (err = %d)\n",
+			   ret);
+		goto rx_handler_failed;
+	}
+
+	ret = netdev_upper_dev_link(vf_netdev, ndev);
+	if (ret != 0) {
+		netdev_err(vf_netdev,
+			   "can not set master device %s (err = %d)\n",
+			   ndev->name, ret);
+		goto upper_link_failed;
+	}
+
+	/* set slave flag before open to prevent IPv6 addrconf */
+	vf_netdev->flags |= IFF_SLAVE;
+
+	schedule_work(&ndev_ctx->vf_takeover);
+
+	netdev_info(vf_netdev, "joined to %s\n", ndev->name);
+	return 0;
+
+upper_link_failed:
+	netdev_rx_handler_unregister(vf_netdev);
+rx_handler_failed:
+	return ret;
+}
+
+static void __netvsc_vf_setup(struct net_device *ndev,
+			      struct net_device *vf_netdev)
+{
+	int ret;
+
+	call_netdevice_notifiers(NETDEV_JOIN, vf_netdev);
+
+	/* Align MTU of VF with master */
+	ret = dev_set_mtu(vf_netdev, ndev->mtu);
+	if (ret)
+		netdev_warn(vf_netdev,
+			    "unable to change mtu to %u\n", ndev->mtu);
+
+	if (netif_running(ndev)) {
+		ret = dev_open(vf_netdev);
+		if (ret)
+			netdev_warn(vf_netdev,
+				    "unable to open: %d\n", ret);
+	}
+}
+
+/* Setup VF as slave of the synthetic device.
+ * Runs in workqueue to avoid recursion in netlink callbacks.
+ */
+static void netvsc_vf_setup(struct work_struct *w)
+{
+	struct net_device_context *ndev_ctx
+		= container_of(w, struct net_device_context, vf_takeover);
+	struct net_device *ndev = hv_get_drvdata(ndev_ctx->device_ctx);
+	struct net_device *vf_netdev;
+
+	rtnl_lock();
+	vf_netdev = rtnl_dereference(ndev_ctx->vf_netdev);
+	if (vf_netdev)
+		__netvsc_vf_setup(ndev, vf_netdev);
+
+	rtnl_unlock();
+}
+
 static int netvsc_register_vf(struct net_device *vf_netdev)
 {
 	struct net_device *ndev;
@@ -1409,10 +1632,12 @@ static int netvsc_register_vf(struct net_device *vf_netdev)
 	if (!netvsc_dev || rtnl_dereference(net_device_ctx->vf_netdev))
 		return NOTIFY_DONE;
 
+	if (netvsc_vf_join(vf_netdev, ndev) != 0)
+		return NOTIFY_DONE;
+
 	netdev_info(ndev, "VF registering: %s\n", vf_netdev->name);
-	/*
-	 * Take a reference on the module.
-	 */
+
+	/* Prevent this module from being unloaded while VF is registered */
 	try_module_get(THIS_MODULE);
 
 	dev_hold(vf_netdev);
@@ -1420,61 +1645,59 @@ static int netvsc_register_vf(struct net_device *vf_netdev)
 	return NOTIFY_OK;
 }
 
-static int netvsc_vf_up(struct net_device *vf_netdev)
+/* Change datapath */
+static void netvsc_vf_update(struct work_struct *w)
 {
-	struct net_device *ndev;
+	struct net_device_context *ndev_ctx
+		= container_of(w, struct net_device_context, vf_notify);
+	struct net_device *ndev = hv_get_drvdata(ndev_ctx->device_ctx);
 	struct netvsc_device *netvsc_dev;
-	struct net_device_context *net_device_ctx;
-
-	ndev = get_netvsc_byref(vf_netdev);
-	if (!ndev)
-		return NOTIFY_DONE;
-
-	net_device_ctx = netdev_priv(ndev);
-	netvsc_dev = rtnl_dereference(net_device_ctx->nvdev);
-
-	netdev_info(ndev, "VF up: %s\n", vf_netdev->name);
-
-	/*
-	 * Open the device before switching data path.
-	 */
-	rndis_filter_open(netvsc_dev);
-
-	/*
-	 * notify the host to switch the data path.
-	 */
-	netvsc_switch_datapath(ndev, true);
-	netdev_info(ndev, "Data path switched to VF: %s\n", vf_netdev->name);
-
-	netif_carrier_off(ndev);
+	struct net_device *vf_netdev;
+	bool vf_is_up;
 
-	/* Now notify peers through VF device. */
-	call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, vf_netdev);
+	rtnl_lock();
+	vf_netdev = rtnl_dereference(ndev_ctx->vf_netdev);
+	if (!vf_netdev)
+		goto unlock;
+
+	netvsc_dev = rtnl_dereference(ndev_ctx->nvdev);
+	if (!netvsc_dev)
+		goto unlock;
+
+	vf_is_up = netif_running(vf_netdev);
+	if (vf_is_up != ndev_ctx->datapath) {
+		if (vf_is_up) {
+			netdev_info(ndev, "VF up: %s\n", vf_netdev->name);
+			rndis_filter_open(netvsc_dev);
+			netvsc_switch_datapath(ndev, true);
+			netdev_info(ndev, "Data path switched to VF: %s\n",
+				    vf_netdev->name);
+		} else {
+			netdev_info(ndev, "VF down: %s\n", vf_netdev->name);
+			netvsc_switch_datapath(ndev, false);
+			rndis_filter_close(netvsc_dev);
+			netdev_info(ndev, "Data path switched from VF: %s\n",
+				    vf_netdev->name);
+		}
 
-	return NOTIFY_OK;
+		/* Now notify peers through VF device. */
+		call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, ndev);
+	}
+unlock:
+	rtnl_unlock();
 }
 
-static int netvsc_vf_down(struct net_device *vf_netdev)
+static int netvsc_vf_notify(struct net_device *vf_netdev)
 {
-	struct net_device *ndev;
-	struct netvsc_device *netvsc_dev;
 	struct net_device_context *net_device_ctx;
+	struct net_device *ndev;
 
 	ndev = get_netvsc_byref(vf_netdev);
 	if (!ndev)
 		return NOTIFY_DONE;
 
 	net_device_ctx = netdev_priv(ndev);
-	netvsc_dev = rtnl_dereference(net_device_ctx->nvdev);
-
-	netdev_info(ndev, "VF down: %s\n", vf_netdev->name);
-	netvsc_switch_datapath(ndev, false);
-	netdev_info(ndev, "Data path switched from VF: %s\n", vf_netdev->name);
-	rndis_filter_close(netvsc_dev);
-	netif_carrier_on(ndev);
-
-	/* Now notify peers through netvsc device. */
-	call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, ndev);
+	schedule_work(&net_device_ctx->vf_notify);
 
 	return NOTIFY_OK;
 }
@@ -1489,9 +1712,12 @@ static int netvsc_unregister_vf(struct net_device *vf_netdev)
 		return NOTIFY_DONE;
 
 	net_device_ctx = netdev_priv(ndev);
+	cancel_work_sync(&net_device_ctx->vf_takeover);
+	cancel_work_sync(&net_device_ctx->vf_notify);
 
 	netdev_info(ndev, "VF unregistering: %s\n", vf_netdev->name);
 
+	netdev_upper_dev_unlink(vf_netdev, ndev);
 	RCU_INIT_POINTER(net_device_ctx->vf_netdev, NULL);
 	dev_put(vf_netdev);
 	module_put(THIS_MODULE);
@@ -1505,12 +1731,12 @@ static int netvsc_probe(struct hv_device *dev,
 	struct net_device_context *net_device_ctx;
 	struct netvsc_device_info device_info;
 	struct netvsc_device *nvdev;
-	int ret;
+	int ret = -ENOMEM;
 
 	net = alloc_etherdev_mq(sizeof(struct net_device_context),
 				VRSS_CHANNEL_MAX);
 	if (!net)
-		return -ENOMEM;
+		goto no_net;
 
 	netif_carrier_off(net);
 
@@ -1529,6 +1755,13 @@ static int netvsc_probe(struct hv_device *dev,
 
 	spin_lock_init(&net_device_ctx->lock);
 	INIT_LIST_HEAD(&net_device_ctx->reconfig_events);
+	INIT_WORK(&net_device_ctx->vf_takeover, netvsc_vf_setup);
+	INIT_WORK(&net_device_ctx->vf_notify, netvsc_vf_update);
+
+	net_device_ctx->vf_stats
+		= netdev_alloc_pcpu_stats(struct netvsc_vf_pcpu_stats);
+	if (!net_device_ctx->vf_stats)
+		goto no_stats;
 
 	net->netdev_ops = &device_ops;
 	net->ethtool_ops = &ethtool_ops;
@@ -1546,10 +1779,9 @@ static int netvsc_probe(struct hv_device *dev,
 	if (IS_ERR(nvdev)) {
 		ret = PTR_ERR(nvdev);
 		netdev_err(net, "unable to add netvsc device (ret %d)\n", ret);
-		free_netdev(net);
-		hv_set_drvdata(dev, NULL);
-		return ret;
+		goto rndis_failed;
 	}
+
 	memcpy(net->dev_addr, device_info.mac_adr, ETH_ALEN);
 
 	/* hw_features computed in rndis_filter_device_add */
@@ -1573,11 +1805,20 @@ static int netvsc_probe(struct hv_device *dev,
 	ret = register_netdev(net);
 	if (ret != 0) {
 		pr_err("Unable to register netdev.\n");
-		rndis_filter_device_remove(dev, nvdev);
-		free_netdev(net);
+		goto register_failed;
 	}
 
 	return ret;
+
+register_failed:
+	rndis_filter_device_remove(dev, nvdev);
+rndis_failed:
+	free_percpu(net_device_ctx->vf_stats);
+no_stats:
+	hv_set_drvdata(dev, NULL);
+	free_netdev(net);
+no_net:
+	return ret;
 }
 
 static int netvsc_remove(struct hv_device *dev)
@@ -1611,6 +1852,7 @@ static int netvsc_remove(struct hv_device *dev)
 
 	hv_set_drvdata(dev, NULL);
 
+	free_percpu(ndev_ctx->vf_stats);
 	free_netdev(net);
 	return 0;
 }
@@ -1665,9 +1907,8 @@ static int netvsc_netdev_event(struct notifier_block *this,
 	case NETDEV_UNREGISTER:
 		return netvsc_unregister_vf(event_dev);
 	case NETDEV_UP:
-		return netvsc_vf_up(event_dev);
 	case NETDEV_DOWN:
-		return netvsc_vf_down(event_dev);
+		return netvsc_vf_notify(event_dev);
 	default:
 		return NOTIFY_DONE;
 	}

tools/hv/bondvf.sh

-#!/bin/bash
-
-# This example script creates bonding network devices based on synthetic NIC
-# (the virtual network adapter usually provided by Hyper-V) and the matching
-# VF NIC (SRIOV virtual function). So the synthetic NIC and VF NIC can
-# function as one network device, and fail over to the synthetic NIC if VF is
-# down.
-#
-# Usage:
-# - After configured vSwitch and vNIC with SRIOV, start Linux virtual
-#   machine (VM)
-# - Run this scripts on the VM. It will create configuration files in
-#   distro specific directory.
-# - Reboot the VM, so that the bonding config are enabled.
-#
-# The config files are DHCP by default. You may edit them if you need to change
-# to Static IP or change other settings.
-#
-
-sysdir=/sys/class/net
-netvsc_cls={f8615163-df3e-46c5-913f-f2d2f965ed0e}
-bondcnt=0
-
-# Detect Distro
-if [ -f /etc/redhat-release ];
-then
-	cfgdir=/etc/sysconfig/network-scripts
-	distro=redhat
-elif grep -q 'Ubuntu' /etc/issue
-then
-	cfgdir=/etc/network
-	distro=ubuntu
-elif grep -q 'SUSE' /etc/issue
-then
-	cfgdir=/etc/sysconfig/network
-	distro=suse
-else
-	echo "Unsupported Distro"
-	exit 1
-fi
-
-echo Detected Distro: $distro, or compatible
-
-# Get a list of ethernet names
-list_eth=(`cd $sysdir && ls -d */ | cut -d/ -f1 | grep -v bond`)
-eth_cnt=${#list_eth[@]}
-
-echo List of net devices:
-
-# Get the MAC addresses
-for (( i=0; i < $eth_cnt; i++ ))
-do
-	list_mac[$i]=`cat $sysdir/${list_eth[$i]}/address`
-	echo ${list_eth[$i]}, ${list_mac[$i]}
-done
-
-# Find NIC with matching MAC
-for (( i=0; i < $eth_cnt-1; i++ ))
-do
-	for (( j=i+1; j < $eth_cnt; j++ ))
-	do
-		if [ "${list_mac[$i]}" = "${list_mac[$j]}" ]
-		then
-			list_match[$i]=${list_eth[$j]}
-			break
-		fi
-	done
-done
-
-function create_eth_cfg_redhat {
-	local fn=$cfgdir/ifcfg-$1
-
-	rm -f $fn
-	echo DEVICE=$1 >>$fn
-	echo TYPE=Ethernet >>$fn
-	echo BOOTPROTO=none >>$fn
-	echo UUID=`uuidgen` >>$fn
-	echo ONBOOT=yes >>$fn
-	echo PEERDNS=yes >>$fn
-	echo IPV6INIT=yes >>$fn
-	echo MASTER=$2 >>$fn
-	echo SLAVE=yes >>$fn
-}
-
-function create_eth_cfg_pri_redhat {
-	create_eth_cfg_redhat $1 $2
-}
-
-function create_bond_cfg_redhat {
-	local fn=$cfgdir/ifcfg-$1
-
-	rm -f $fn
-	echo DEVICE=$1 >>$fn
-	echo TYPE=Bond >>$fn
-	echo BOOTPROTO=dhcp >>$fn
-	echo UUID=`uuidgen` >>$fn
-	echo ONBOOT=yes >>$fn
-	echo PEERDNS=yes >>$fn
-	echo IPV6INIT=yes >>$fn
-	echo BONDING_MASTER=yes >>$fn
-	echo BONDING_OPTS=\"mode=active-backup miimon=100 primary=$2\" >>$fn
-}
-
-function del_eth_cfg_ubuntu {
-	local mainfn=$cfgdir/interfaces
-	local fnlist=( $mainfn )
-
-	local dirlist=(`awk '/^[ \t]*source/{print $2}' $mainfn`)
-
-	local i
-	for i in "${dirlist[@]}"
-	do
-		fnlist+=(`ls $i 2>/dev/null`)
-	done
-
-	local tmpfl=$(mktemp)
-
-	local nic_start='^[ \t]*(auto|iface|mapping|allow-.*)[ \t]+'$1
-	local nic_end='^[ \t]*(auto|iface|mapping|allow-.*|source)'
-
-	local fn
-	for fn in "${fnlist[@]}"
-	do
-		awk "/$nic_end/{x=0} x{next} /$nic_start/{x=1;next} 1" \
-			$fn >$tmpfl
-
-		cp $tmpfl $fn
-	done
-
-	rm $tmpfl
-}
-
-function create_eth_cfg_ubuntu {
-	local fn=$cfgdir/interfaces
-
-	del_eth_cfg_ubuntu $1
-	echo $'\n'auto $1 >>$fn
-	echo iface $1 inet manual >>$fn
-	echo bond-master $2 >>$fn
-}
-
-function create_eth_cfg_pri_ubuntu {
-	local fn=$cfgdir/interfaces
-
-	del_eth_cfg_ubuntu $1
-	echo $'\n'allow-hotplug $1 >>$fn
-	echo iface $1 inet manual >>$fn
-	echo bond-master $2 >>$fn
-	echo bond-primary $1 >>$fn
-}
-
-function create_bond_cfg_ubuntu {
-	local fn=$cfgdir/interfaces
-
-	del_eth_cfg_ubuntu $1
-
-	echo $'\n'auto $1 >>$fn
-	echo iface $1 inet dhcp >>$fn
-	echo bond-mode active-backup >>$fn
-	echo bond-miimon 100 >>$fn
-	echo bond-slaves none >>$fn
-}
-
-function create_eth_cfg_suse {
-        local fn=$cfgdir/ifcfg-$1
-
-        rm -f $fn
-	echo BOOTPROTO=none >>$fn
-	echo STARTMODE=auto >>$fn
-}
-
-function create_eth_cfg_pri_suse {
-	local fn=$cfgdir/ifcfg-$1
-
-	rm -f $fn
-	echo BOOTPROTO=none >>$fn
-	echo STARTMODE=hotplug >>$fn
-}
-
-function create_bond_cfg_suse {
-	local fn=$cfgdir/ifcfg-$1
-
-	rm -f $fn
-	echo BOOTPROTO=dhcp >>$fn
-	echo STARTMODE=auto >>$fn
-	echo BONDING_MASTER=yes >>$fn
-	echo BONDING_SLAVE_0=$2 >>$fn
-	echo BONDING_SLAVE_1=$3 >>$fn
-	echo BONDING_MODULE_OPTS=\'mode=active-backup miimon=100 primary=$2\' >>$fn
-}
-
-function create_bond {
-	local bondname=bond$bondcnt
-	local primary
-	local secondary
-
-	local class_id1=`cat $sysdir/$1/device/class_id 2>/dev/null`
-	local class_id2=`cat $sysdir/$2/device/class_id 2>/dev/null`
-
-	if [ "$class_id1" = "$netvsc_cls" ]
-	then
-		primary=$2
-		secondary=$1
-	elif [ "$class_id2" = "$netvsc_cls" ]
-	then
-		primary=$1
-		secondary=$2
-	else
-		return 0
-	fi
-
-	echo $'\nBond name:' $bondname
-
-	if [ $distro == ubuntu ]
-	then
-		local mainfn=$cfgdir/interfaces
-		local s="^[ \t]*(auto|iface|mapping|allow-.*)[ \t]+${bondname}"
-
-		grep -E "$s" $mainfn
-		if [ $? -eq 0 ]
-		then
-			echo "WARNING: ${bondname} has been configured already"
-			return
-		fi
-	elif [ $distro == redhat ] || [ $distro == suse ]
-	then
-		local fn=$cfgdir/ifcfg-$bondname
-		if [ -f $fn ]
-		then
-			echo "WARNING: ${bondname} has been configured already"
-			return
-		fi
-	else
-		echo "Unsupported Distro: ${distro}"
-		return
-	fi
-
-	echo configuring $primary
-	create_eth_cfg_pri_$distro $primary $bondname
-
-	echo configuring $secondary
-	create_eth_cfg_$distro $secondary $bondname
-
-	echo creating: $bondname with primary slave: $primary
-	create_bond_cfg_$distro $bondname $primary $secondary
-}
-
-for (( i=0; i < $eth_cnt-1; i++ ))
-do
-        if [ -n "${list_match[$i]}" ]
-        then
-		create_bond ${list_eth[$i]} ${list_match[$i]}
-		let bondcnt=bondcnt+1
-        fi
-done