[PATCH net-next v8 0/4] Enable virtio_net to act as a standby for a passthru device

[PATCH net-next v8 0/4] Enable virtio_net to act as a standby for a passthru device

[Sridhar Samudrala]

This is another update based on feedback from MST and Stephen on the
last patchset. Hopefully this series can be integrated and any further
enhancements can be made on top of this patchset.

v8:
- Made the failover managment routines more robust by updating the feature 
  bits/other fields in the failover netdev when slave netdevs are 
  registered/unregistered. (mst)
- added support for handling vlans.
- Limited the changes in netvsc to only use the notifier/event/lookups
  from the failover module. The slave register/unregister/link-change 
  handlers are only updated to use the getbymac routine to get the 
  upper netdev. There is no change in their functionality. (stephen)
- renamed structs/function/file names to use net_failover prefix. (mst)

The main motivation for this patch is to enable cloud service providers
to provide an accelerated datapath to virtio-net enabled VMs in a 
transparent manner with no/minimal guest userspace changes. This also
enables hypervisor controlled live migration to be supported with VMs that
have direct attached SR-IOV VF devices.

Patch 1 introduces a new feature bit VIRTIO_NET_F_STANDBY that can be
used by hypervisor to indicate that virtio_net interface should act as
a standby for another device with the same MAC address.

Patch 2 introduces a failover module that provides a generic interface for 
paravirtual drivers to listen for netdev register/unregister/link change
events from pci ethernet devices with the same MAC and takeover their
datapath. The notifier and event handling code is based on the existing
netvsc implementation. It provides 2 sets of interfaces to paravirtual 
drivers to support 2-netdev(netvsc) and 3-netdev(virtio_net) models.

Patch 3 extends virtio_net to use alternate datapath when available and
registered. When STANDBY feature is enabled, virtio_net driver creates
an additional 'failover' netdev that acts as a master device and controls
2 slave devices.  The original virtio_net netdev is registered as
'standby' netdev and a passthru/vf device with the same MAC gets
registered as 'primary' netdev. Both 'standby' and 'primary' netdevs are
associated with the same 'pci' device.  The user accesses the network
interface via 'failover' netdev. The 'failover' netdev chooses 'primary'
netdev as default for transmits when it is available with link up and
running.

Patch 4 refactors netvsc to use the registration/notification framework
supported by failover module.

As this patch series is initially focusing on usecases where hypervisor 
fully controls the VM networking and the guest is not expected to directly 
configure any hardware settings, it doesn't expose all the ndo/ethtool ops
that are supported by virtio_net at this time. To support additional usecases,
it should be possible to enable additional ops later by caching the state
in virtio netdev and replaying when the 'primary' netdev gets registered. 
 
The hypervisor needs to enable only one datapath at any time so that packets
don't get looped back to the VM over the other datapath. When a VF is
plugged, the virtio datapath link state can be marked as down.
At the time of live migration, the hypervisor needs to unplug the VF device
from the guest on the source host and reset the MAC filter of the VF to
initiate failover of datapath to virtio before starting the migration. After
the migration is completed, the destination hypervisor sets the MAC filter
on the VF and plugs it back to the guest to switch over to VF datapath.

This patch is based on the discussion initiated by Jesse on this thread.
https://marc.info/?l=linux-virtualization&m=151189725224231&w=2

v7
- Rename 'bypass/active/backup' terminology with 'failover/primary/standy'
  (jiri, mst)
- re-arranged dev_open() and dev_set_mtu() calls in the register routines
  so that they don't get called for 2-netdev model. (stephen)
- fixed select_queue() routine to do queue selection based on VF if it is
  registered as primary. (stephen)
-  minor bugfixes

v6 RFC:
  Simplified virtio_net changes by moving all the ndo_ops of the 
  bypass_netdev and create/destroy of bypass_netdev to 'bypass' module.
  avoided 2 phase registration(driver + instances).
  introduced IFF_BYPASS/IFF_BYPASS_SLAVE dev->priv_flags 
  replaced mutex with a spinlock

v5 RFC:
  Based on Jiri's comments, moved the common functionality to a 'bypass'
  module so that the same notifier and event handlers to handle child
  register/unregister/link change events can be shared between virtio_net
  and netvsc.
  Improved error handling based on Siwei's comments.
v4:
- Based on the review comments on the v3 version of the RFC patch and
  Jakub's suggestion for the naming issue with 3 netdev solution,
  proposed 3 netdev in-driver bonding solution for virtio-net.
v3 RFC:
- Introduced 3 netdev model and pointed out a couple of issues with
  that model and proposed 2 netdev model to avoid these issues.
- Removed broadcast/multicast optimization and only use virtio as
  backup path when VF is unplugged.
v2 RFC:
- Changed VIRTIO_NET_F_MASTER to VIRTIO_NET_F_BACKUP (mst)
- made a small change to the virtio-net xmit path to only use VF datapath
  for unicasts. Broadcasts/multicasts use virtio datapath. This avoids
  east-west broadcasts to go over the PCI link.
- added suppport for the feature bit in qemu

Sridhar Samudrala (4):
  virtio_net: Introduce VIRTIO_NET_F_STANDBY feature bit
  net: Introduce generic failover module
  virtio_net: Extend virtio to use VF datapath when available
  netvsc: refactor notifier/event handling code to use the failover
    framework

 drivers/net/Kconfig             |   1 +
 drivers/net/hyperv/Kconfig      |   1 +
 drivers/net/hyperv/hyperv_net.h |   2 +
 drivers/net/hyperv/netvsc_drv.c | 134 ++----
 drivers/net/virtio_net.c        |  37 +-
 include/linux/netdevice.h       |  16 +
 include/net/net_failover.h      |  94 +++++
 include/uapi/linux/virtio_net.h |   3 +
 net/Kconfig                     |  18 +
 net/core/Makefile               |   1 +
 net/core/net_failover.c         | 892 ++++++++++++++++++++++++++++++++++++++++
 11 files changed, 1086 insertions(+), 113 deletions(-)
 create mode 100644 include/net/net_failover.h
 create mode 100644 net/core/net_failover.c

-- 
2.14.3

[PATCH net-next v8 1/4] virtio_net: Introduce VIRTIO_NET_F_STANDBY feature bit

[Sridhar Samudrala]

This feature bit can be used by hypervisor to indicate virtio_net device to
act as a standby for another device with the same MAC address.

VIRTIO_NET_F_STANDBY is defined as bit 62 as it is a device feature bit.

Signed-off-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
---
 drivers/net/virtio_net.c        | 2 +-
 include/uapi/linux/virtio_net.h | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 3b5991734118..51a085b1a242 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2999,7 +2999,7 @@ static struct virtio_device_id id_table[] = {
 	VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ, \
 	VIRTIO_NET_F_CTRL_MAC_ADDR, \
 	VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, \
-	VIRTIO_NET_F_SPEED_DUPLEX
+	VIRTIO_NET_F_SPEED_DUPLEX, VIRTIO_NET_F_STANDBY
 
 static unsigned int features[] = {
 	VIRTNET_FEATURES,
diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
index 5de6ed37695b..a3715a3224c1 100644
--- a/include/uapi/linux/virtio_net.h
+++ b/include/uapi/linux/virtio_net.h
@@ -57,6 +57,9 @@
 					 * Steering */
 #define VIRTIO_NET_F_CTRL_MAC_ADDR 23	/* Set MAC address */
 
+#define VIRTIO_NET_F_STANDBY	  62	/* Act as standby for another device
+					 * with the same MAC.
+					 */
 #define VIRTIO_NET_F_SPEED_DUPLEX 63	/* Device set linkspeed and duplex */
 
 #ifndef VIRTIO_NET_NO_LEGACY
-- 
2.14.3

[PATCH net-next v8 2/4] net: Introduce generic failover module

[Sridhar Samudrala]

This provides a generic interface for paravirtual drivers to listen
for netdev register/unregister/link change events from pci ethernet
devices with the same MAC and takeover their datapath. The notifier and
event handling code is based on the existing netvsc implementation.

It exposes 2 sets of interfaces to the paravirtual drivers.
1. For paravirtual drivers like virtio_net that use 3 netdev model, the
   the failover module provides interfaces to create/destroy additional
   master netdev and all the slave events are managed internally.
        net_failover_create()
        net_failover_destroy()
   A failover netdev is created that acts a master device and controls 2
   slave devices. The original virtio_net netdev is registered as 'standby'
   netdev and a passthru/vf device with the same MAC gets registered as
   'primary' netdev. Both 'standby' and 'primary' netdevs are associated
   with the same 'pci' device.  The user accesses the network interface via
   'failover' netdev. The 'failover' netdev chooses 'primary' netdev as
   default for transmits when it is available with link up and running.
2. For existing netvsc driver that uses 2 netdev model, no master netdev
   is created. The paravirtual driver registers each instance of netvsc
   as a 'failover' netdev  along with a set of ops to manage the slave
   events. There is no 'standby' netdev in this model. A passthru/vf device
   with the same MAC gets registered as 'primary' netdev.
        net_failover_register()
        net_failover_unregister()

Signed-off-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
---
 include/linux/netdevice.h  |  16 +
 include/net/net_failover.h |  94 +++++
 net/Kconfig                |  18 +
 net/core/Makefile          |   1 +
 net/core/net_failover.c    | 892 +++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 1021 insertions(+)
 create mode 100644 include/net/net_failover.h
 create mode 100644 net/core/net_failover.c

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 14e0777ffcfb..b04dbf7dcf1b 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1401,6 +1401,8 @@ struct net_device_ops {
  *	entity (i.e. the master device for bridged veth)
  * @IFF_MACSEC: device is a MACsec device
  * @IFF_NO_RX_HANDLER: device doesn't support the rx_handler hook
+ * @IFF_FAILOVER: device is a failover master device
+ * @IFF_FAILOVER_SLAVE: device is lower dev of a failover master device
  */
 enum netdev_priv_flags {
 	IFF_802_1Q_VLAN			= 1<<0,
@@ -1430,6 +1432,8 @@ enum netdev_priv_flags {
 	IFF_PHONY_HEADROOM		= 1<<24,
 	IFF_MACSEC			= 1<<25,
 	IFF_NO_RX_HANDLER		= 1<<26,
+	IFF_FAILOVER			= 1<<27,
+	IFF_FAILOVER_SLAVE		= 1<<28,
 };
 
 #define IFF_802_1Q_VLAN			IFF_802_1Q_VLAN
@@ -1458,6 +1462,8 @@ enum netdev_priv_flags {
 #define IFF_RXFH_CONFIGURED		IFF_RXFH_CONFIGURED
 #define IFF_MACSEC			IFF_MACSEC
 #define IFF_NO_RX_HANDLER		IFF_NO_RX_HANDLER
+#define IFF_FAILOVER			IFF_FAILOVER
+#define IFF_FAILOVER_SLAVE		IFF_FAILOVER_SLAVE
 
 /**
  *	struct net_device - The DEVICE structure.
@@ -4308,6 +4314,16 @@ static inline bool netif_is_rxfh_configured(const struct net_device *dev)
 	return dev->priv_flags & IFF_RXFH_CONFIGURED;
 }
 
+static inline bool netif_is_failover(const struct net_device *dev)
+{
+	return dev->priv_flags & IFF_FAILOVER;
+}
+
+static inline bool netif_is_failover_slave(const struct net_device *dev)
+{
+	return dev->priv_flags & IFF_FAILOVER_SLAVE;
+}
+
 /* This device needs to keep skb dst for qdisc enqueue or ndo_start_xmit() */
 static inline void netif_keep_dst(struct net_device *dev)
 {
diff --git a/include/net/net_failover.h b/include/net/net_failover.h
new file mode 100644
index 000000000000..8d431685634a
--- /dev/null
+++ b/include/net/net_failover.h
@@ -0,0 +1,94 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2018, Intel Corporation. */
+
+#ifndef _NET_FAILOVER_H
+#define _NET_FAILOVER_H
+
+#include <linux/netdevice.h>
+
+struct net_failover_ops {
+	int (*slave_register)(struct net_device *slave_dev,
+			      struct net_device *failover_dev);
+	int (*slave_unregister)(struct net_device *slave_dev,
+				struct net_device *failover_dev);
+	int (*slave_link_change)(struct net_device *slave_dev,
+				 struct net_device *failover_dev);
+};
+
+struct net_failover {
+	struct list_head list;
+	struct net_device __rcu *failover_dev;
+	struct net_failover_ops __rcu *ops;
+};
+
+/* failover state */
+struct net_failover_info {
+	/* primary netdev with same MAC */
+	struct net_device __rcu *primary_dev;
+
+	/* standby netdev */
+	struct net_device __rcu *standby_dev;
+
+	/* primary netdev stats */
+	struct rtnl_link_stats64 primary_stats;
+
+	/* standby netdev stats */
+	struct rtnl_link_stats64 standby_stats;
+
+	/* aggregated stats */
+	struct rtnl_link_stats64 failover_stats;
+
+	/* spinlock while updating stats */
+	spinlock_t stats_lock;
+};
+
+#if IS_ENABLED(CONFIG_NET_FAILOVER)
+
+/* Paravirtual drivers supporting 3-netdev model can use these 2 interfaces to
+ * create and destroy a failover device.
+ */
+int net_failover_create(struct net_device *standby_dev,
+			struct net_failover **pfailover);
+void net_failover_destroy(struct net_failover *failover);
+
+/* Paravirtual drivers supporting 2-netdev model can use these 2 interfaces to
+ * register and unregister a failover device.
+ */
+int net_failover_register(struct net_device *standby_dev,
+			  struct net_failover_ops *ops,
+			  struct net_failover **pfailover);
+void net_failover_unregister(struct net_failover *failover);
+
+int net_failover_slave_unregister(struct net_device *slave_dev);
+
+#else
+
+static inline int net_failover_create(struct net_device *standby_dev,
+				      struct net_failover **pfailover)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void net_failover_destroy(struct net_failover *failover)
+{
+}
+
+static inline int net_failover_register(struct net_device *standby_dev,
+					struct net_failover_ops *ops,
+					struct net_failover **pfailover)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void net_failover_unregister(struct net_failover *failover)
+{
+}
+
+static inline int net_failover_slave_unregister(struct net_device *slave_dev)
+{
+	return 0;
+}
+
+#endif
+
+#endif /* _NET_FAILOVER_H */
diff --git a/net/Kconfig b/net/Kconfig
index 6fa1a4493b8c..e8fe3163c5d3 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -426,6 +426,24 @@ config MAY_USE_DEVLINK
 config PAGE_POOL
        bool
 
+config NET_FAILOVER
+	tristate "Failover interface"
+	help
+	  This provides a generic interface for paravirtual drivers to listen
+	  for netdev register/unregister/link change events from pci ethernet
+	  devices with the same MAC and takeover their datapath. This also
+	  enables live migration of a VM with direct attached VF by failing
+	  over to the paravirtual datapath when the VF is unplugged.
+
+config MAY_USE_NET_FAILOVER
+	tristate
+	default m if NET_FAILOVER=m
+	default y if NET_FAILOVER=y || NET_FAILOVER=n
+	help
+	  Drivers using the failover infrastructure should have a dependency
+	  on MAY_USE_NET_FAILOVER to ensure they do not cause link errors when
+	  failover is a loadable module and the driver using it is built-in.
+
 endif   # if NET
 
 # Used by archs to tell that they support BPF JIT compiler plus which flavour.
diff --git a/net/core/Makefile b/net/core/Makefile
index 7080417f8bc8..283ed9b0e581 100644
--- a/net/core/Makefile
+++ b/net/core/Makefile
@@ -31,3 +31,4 @@ obj-$(CONFIG_DST_CACHE) += dst_cache.o
 obj-$(CONFIG_HWBM) += hwbm.o
 obj-$(CONFIG_NET_DEVLINK) += devlink.o
 obj-$(CONFIG_GRO_CELLS) += gro_cells.o
+obj-$(CONFIG_NET_FAILOVER) += net_failover.o
diff --git a/net/core/net_failover.c b/net/core/net_failover.c
new file mode 100644
index 000000000000..ac164be17563
--- /dev/null
+++ b/net/core/net_failover.c
@@ -0,0 +1,892 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2018, Intel Corporation. */
+
+/* A common module to handle registrations and notifications for paravirtual
+ * drivers to enable accelerated datapath and support VF live migration.
+ *
+ * The notifier and event handling code is based on netvsc driver and failover
+ * netdev management routines are based on bond/team driver.
+ *
+ */
+
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/ethtool.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/netdevice.h>
+#include <linux/netpoll.h>
+#include <linux/rtnetlink.h>
+#include <linux/if_vlan.h>
+#include <linux/pci.h>
+#include <net/sch_generic.h>
+#include <uapi/linux/if_arp.h>
+#include <net/net_failover.h>
+
+static LIST_HEAD(net_failover_list);
+static DEFINE_SPINLOCK(net_failover_lock);
+
+static int net_failover_open(struct net_device *dev)
+{
+	struct net_failover_info *nfo_info = netdev_priv(dev);
+	struct net_device *primary_dev, *standby_dev;
+	int err;
+
+	netif_carrier_off(dev);
+	netif_tx_wake_all_queues(dev);
+
+	primary_dev = rtnl_dereference(nfo_info->primary_dev);
+	if (primary_dev) {
+		err = dev_open(primary_dev);
+		if (err)
+			goto err_primary_open;
+	}
+
+	standby_dev = rtnl_dereference(nfo_info->standby_dev);
+	if (standby_dev) {
+		err = dev_open(standby_dev);
+		if (err)
+			goto err_standby_open;
+	}
+
+	return 0;
+
+err_standby_open:
+	dev_close(primary_dev);
+err_primary_open:
+	netif_tx_disable(dev);
+	return err;
+}
+
+static int net_failover_close(struct net_device *dev)
+{
+	struct net_failover_info *nfo_info = netdev_priv(dev);
+	struct net_device *slave_dev;
+
+	netif_tx_disable(dev);
+
+	slave_dev = rtnl_dereference(nfo_info->primary_dev);
+	if (slave_dev)
+		dev_close(slave_dev);
+
+	slave_dev = rtnl_dereference(nfo_info->standby_dev);
+	if (slave_dev)
+		dev_close(slave_dev);
+
+	return 0;
+}
+
+static netdev_tx_t net_failover_drop_xmit(struct sk_buff *skb,
+					  struct net_device *dev)
+{
+	atomic_long_inc(&dev->tx_dropped);
+	dev_kfree_skb_any(skb);
+	return NETDEV_TX_OK;
+}
+
+static bool net_failover_xmit_ready(struct net_device *dev)
+{
+	return netif_running(dev) && netif_carrier_ok(dev);
+}
+
+static netdev_tx_t net_failover_start_xmit(struct sk_buff *skb,
+					   struct net_device *dev)
+{
+	struct net_failover_info *nfo_info = netdev_priv(dev);
+	struct net_device *xmit_dev;
+
+	/* Try xmit via primary netdev followed by standby netdev */
+	xmit_dev = rcu_dereference_bh(nfo_info->primary_dev);
+	if (!xmit_dev || !net_failover_xmit_ready(xmit_dev)) {
+		xmit_dev = rcu_dereference_bh(nfo_info->standby_dev);
+		if (!xmit_dev || !net_failover_xmit_ready(xmit_dev))
+			return net_failover_drop_xmit(skb, dev);
+	}
+
+	skb->dev = xmit_dev;
+	skb->queue_mapping = qdisc_skb_cb(skb)->slave_dev_queue_mapping;
+
+	return dev_queue_xmit(skb);
+}
+
+static u16 net_failover_select_queue(struct net_device *dev,
+				     struct sk_buff *skb, void *accel_priv,
+				     select_queue_fallback_t fallback)
+{
+	struct net_failover_info *nfo_info = netdev_priv(dev);
+	struct net_device *primary_dev;
+	u16 txq;
+
+	rcu_read_lock();
+	primary_dev = rcu_dereference(nfo_info->primary_dev);
+	if (primary_dev) {
+		const struct net_device_ops *ops = primary_dev->netdev_ops;
+
+		if (ops->ndo_select_queue)
+			txq = ops->ndo_select_queue(primary_dev, skb,
+						    accel_priv, fallback);
+		else
+			txq = fallback(primary_dev, skb);
+
+		qdisc_skb_cb(skb)->slave_dev_queue_mapping = skb->queue_mapping;
+
+		return txq;
+	}
+
+	txq = skb_rx_queue_recorded(skb) ? skb_get_rx_queue(skb) : 0;
+
+	/* Save the original txq to restore before passing to the driver */
+	qdisc_skb_cb(skb)->slave_dev_queue_mapping = skb->queue_mapping;
+
+	if (unlikely(txq >= dev->real_num_tx_queues)) {
+		do {
+			txq -= dev->real_num_tx_queues;
+		} while (txq >= dev->real_num_tx_queues);
+	}
+
+	return txq;
+}
+
+/* fold stats, assuming all rtnl_link_stats64 fields are u64, but
+ * that some drivers can provide 32bit values only.
+ */
+static void net_failover_fold_stats(struct rtnl_link_stats64 *_res,
+				    const struct rtnl_link_stats64 *_new,
+				    const struct rtnl_link_stats64 *_old)
+{
+	const u64 *new = (const u64 *)_new;
+	const u64 *old = (const u64 *)_old;
+	u64 *res = (u64 *)_res;
+	int i;
+
+	for (i = 0; i < sizeof(*_res) / sizeof(u64); i++) {
+		u64 nv = new[i];
+		u64 ov = old[i];
+		s64 delta = nv - ov;
+
+		/* detects if this particular field is 32bit only */
+		if (((nv | ov) >> 32) == 0)
+			delta = (s64)(s32)((u32)nv - (u32)ov);
+
+		/* filter anomalies, some drivers reset their stats
+		 * at down/up events.
+		 */
+		if (delta > 0)
+			res[i] += delta;
+	}
+}
+
+static void net_failover_get_stats(struct net_device *dev,
+				   struct rtnl_link_stats64 *stats)
+{
+	struct net_failover_info *nfo_info = netdev_priv(dev);
+	const struct rtnl_link_stats64 *new;
+	struct rtnl_link_stats64 temp;
+	struct net_device *slave_dev;
+
+	spin_lock(&nfo_info->stats_lock);
+	memcpy(stats, &nfo_info->failover_stats, sizeof(*stats));
+
+	rcu_read_lock();
+
+	slave_dev = rcu_dereference(nfo_info->primary_dev);
+	if (slave_dev) {
+		new = dev_get_stats(slave_dev, &temp);
+		net_failover_fold_stats(stats, new, &nfo_info->primary_stats);
+		memcpy(&nfo_info->primary_stats, new, sizeof(*new));
+	}
+
+	slave_dev = rcu_dereference(nfo_info->standby_dev);
+	if (slave_dev) {
+		new = dev_get_stats(slave_dev, &temp);
+		net_failover_fold_stats(stats, new, &nfo_info->standby_stats);
+		memcpy(&nfo_info->standby_stats, new, sizeof(*new));
+	}
+
+	rcu_read_unlock();
+
+	memcpy(&nfo_info->failover_stats, stats, sizeof(*stats));
+	spin_unlock(&nfo_info->stats_lock);
+}
+
+static int net_failover_change_mtu(struct net_device *dev, int new_mtu)
+{
+	struct net_failover_info *nfo_info = netdev_priv(dev);
+	struct net_device *primary_dev, *standby_dev;
+	int ret = 0;
+
+	primary_dev = rcu_dereference(nfo_info->primary_dev);
+	if (primary_dev) {
+		ret = dev_set_mtu(primary_dev, new_mtu);
+		if (ret)
+			return ret;
+	}
+
+	standby_dev = rcu_dereference(nfo_info->standby_dev);
+	if (standby_dev) {
+		ret = dev_set_mtu(standby_dev, new_mtu);
+		if (ret) {
+			dev_set_mtu(primary_dev, dev->mtu);
+			return ret;
+		}
+	}
+
+	dev->mtu = new_mtu;
+
+	return 0;
+}
+
+static void net_failover_set_rx_mode(struct net_device *dev)
+{
+	struct net_failover_info *nfo_info = netdev_priv(dev);
+	struct net_device *slave_dev;
+
+	rcu_read_lock();
+
+	slave_dev = rcu_dereference(nfo_info->primary_dev);
+	if (slave_dev) {
+		dev_uc_sync_multiple(slave_dev, dev);
+		dev_mc_sync_multiple(slave_dev, dev);
+	}
+
+	slave_dev = rcu_dereference(nfo_info->standby_dev);
+	if (slave_dev) {
+		dev_uc_sync_multiple(slave_dev, dev);
+		dev_mc_sync_multiple(slave_dev, dev);
+	}
+
+	rcu_read_unlock();
+}
+
+static int net_failover_vlan_rx_add_vid(struct net_device *dev, __be16 proto,
+					u16 vid)
+{
+	struct net_failover_info *nfo_info = netdev_priv(dev);
+	struct net_device *primary_dev, *standby_dev;
+	int ret = 0;
+
+	primary_dev = rcu_dereference(nfo_info->primary_dev);
+	if (primary_dev) {
+		ret = vlan_vid_add(primary_dev, proto, vid);
+		if (ret)
+			return ret;
+	}
+
+	standby_dev = rcu_dereference(nfo_info->standby_dev);
+	if (standby_dev) {
+		ret = vlan_vid_add(standby_dev, proto, vid);
+		if (ret)
+			vlan_vid_del(primary_dev, proto, vid);
+	}
+
+	return ret;
+}
+
+static int net_failover_vlan_rx_kill_vid(struct net_device *dev, __be16 proto,
+					 u16 vid)
+{
+	struct net_failover_info *nfo_info = netdev_priv(dev);
+	struct net_device *slave_dev;
+
+	slave_dev = rcu_dereference(nfo_info->primary_dev);
+	if (slave_dev)
+		vlan_vid_del(slave_dev, proto, vid);
+
+	slave_dev = rcu_dereference(nfo_info->standby_dev);
+	if (slave_dev)
+		vlan_vid_del(slave_dev, proto, vid);
+
+	return 0;
+}
+
+static const struct net_device_ops failover_dev_ops = {
+	.ndo_open		= net_failover_open,
+	.ndo_stop		= net_failover_close,
+	.ndo_start_xmit		= net_failover_start_xmit,
+	.ndo_select_queue	= net_failover_select_queue,
+	.ndo_get_stats64	= net_failover_get_stats,
+	.ndo_change_mtu		= net_failover_change_mtu,
+	.ndo_set_rx_mode	= net_failover_set_rx_mode,
+	.ndo_vlan_rx_add_vid	= net_failover_vlan_rx_add_vid,
+	.ndo_vlan_rx_kill_vid	= net_failover_vlan_rx_kill_vid,
+	.ndo_validate_addr	= eth_validate_addr,
+	.ndo_features_check	= passthru_features_check,
+};
+
+#define FAILOVER_NAME "failover"
+#define FAILOVER_VERSION "0.1"
+
+static void nfo_ethtool_get_drvinfo(struct net_device *dev,
+				    struct ethtool_drvinfo *drvinfo)
+{
+	strlcpy(drvinfo->driver, FAILOVER_NAME, sizeof(drvinfo->driver));
+	strlcpy(drvinfo->version, FAILOVER_VERSION, sizeof(drvinfo->version));
+}
+
+static int nfo_ethtool_get_link_ksettings(struct net_device *dev,
+					  struct ethtool_link_ksettings *cmd)
+{
+	struct net_failover_info *nfo_info = netdev_priv(dev);
+	struct net_device *slave_dev;
+
+	slave_dev = rtnl_dereference(nfo_info->primary_dev);
+	if (!slave_dev || !net_failover_xmit_ready(slave_dev)) {
+		slave_dev = rtnl_dereference(nfo_info->standby_dev);
+		if (!slave_dev || !net_failover_xmit_ready(slave_dev)) {
+			cmd->base.duplex = DUPLEX_UNKNOWN;
+			cmd->base.port = PORT_OTHER;
+			cmd->base.speed = SPEED_UNKNOWN;
+
+			return 0;
+		}
+	}
+
+	return __ethtool_get_link_ksettings(slave_dev, cmd);
+}
+
+static const struct ethtool_ops failover_ethtool_ops = {
+	.get_drvinfo            = nfo_ethtool_get_drvinfo,
+	.get_link               = ethtool_op_get_link,
+	.get_link_ksettings     = nfo_ethtool_get_link_ksettings,
+};
+
+static struct net_device *net_failover_get_bymac(u8 *mac,
+						 struct net_failover_ops **ops)
+{
+	struct net_device *failover_dev;
+	struct net_failover *failover;
+
+	spin_lock(&net_failover_lock);
+	list_for_each_entry(failover, &net_failover_list, list) {
+		failover_dev = rtnl_dereference(failover->failover_dev);
+		if (ether_addr_equal(failover_dev->perm_addr, mac)) {
+			*ops = rtnl_dereference(failover->ops);
+			spin_unlock(&net_failover_lock);
+			return failover_dev;
+		}
+	}
+	spin_unlock(&net_failover_lock);
+	return NULL;
+}
+
+/* Called when slave dev is injecting data into network stack.
+ * Change the associated network device from lower dev to virtio.
+ * note: already called with rcu_read_lock
+ */
+static rx_handler_result_t net_failover_handle_frame(struct sk_buff **pskb)
+{
+	struct sk_buff *skb = *pskb;
+	struct net_device *ndev = rcu_dereference(skb->dev->rx_handler_data);
+
+	skb->dev = ndev;
+
+	return RX_HANDLER_ANOTHER;
+}
+
+#define FAILOVER_VLAN_FEATURES	(NETIF_F_HW_CSUM | NETIF_F_SG | \
+				 NETIF_F_FRAGLIST | NETIF_F_ALL_TSO | \
+				 NETIF_F_HIGHDMA | NETIF_F_LRO)
+
+#define FAILOVER_ENC_FEATURES	(NETIF_F_HW_CSUM | NETIF_F_SG | \
+				 NETIF_F_RXCSUM | NETIF_F_ALL_TSO)
+
+static void net_failover_compute_features(struct net_device *dev)
+{
+	u32 vlan_features = FAILOVER_VLAN_FEATURES & NETIF_F_ALL_FOR_ALL;
+	netdev_features_t enc_features  = FAILOVER_ENC_FEATURES;
+	unsigned short max_hard_header_len = ETH_HLEN;
+	unsigned int dst_release_flag = IFF_XMIT_DST_RELEASE |
+					IFF_XMIT_DST_RELEASE_PERM;
+	struct net_failover_info *nfo_info = netdev_priv(dev);
+	struct net_device *primary_dev, *standby_dev;
+
+	primary_dev = rcu_dereference(nfo_info->primary_dev);
+	if (primary_dev) {
+		vlan_features =
+			netdev_increment_features(vlan_features,
+						  primary_dev->vlan_features,
+						  FAILOVER_VLAN_FEATURES);
+		enc_features =
+			netdev_increment_features(enc_features,
+						  primary_dev->hw_enc_features,
+						  FAILOVER_ENC_FEATURES);
+
+		dst_release_flag &= primary_dev->priv_flags;
+		if (primary_dev->hard_header_len > max_hard_header_len)
+			max_hard_header_len = primary_dev->hard_header_len;
+	}
+
+	standby_dev = rcu_dereference(nfo_info->standby_dev);
+	if (standby_dev) {
+		vlan_features =
+			netdev_increment_features(vlan_features,
+						  standby_dev->vlan_features,
+						  FAILOVER_VLAN_FEATURES);
+		enc_features =
+			netdev_increment_features(enc_features,
+						  standby_dev->hw_enc_features,
+						  FAILOVER_ENC_FEATURES);
+
+		dst_release_flag &= standby_dev->priv_flags;
+		if (standby_dev->hard_header_len > max_hard_header_len)
+			max_hard_header_len = standby_dev->hard_header_len;
+	}
+
+	dev->vlan_features = vlan_features;
+	dev->hw_enc_features = enc_features | NETIF_F_GSO_ENCAP_ALL;
+	dev->hard_header_len = max_hard_header_len;
+
+	dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
+	if (dst_release_flag == (IFF_XMIT_DST_RELEASE |
+				 IFF_XMIT_DST_RELEASE_PERM))
+		dev->priv_flags |= IFF_XMIT_DST_RELEASE;
+
+	netdev_change_features(dev);
+}
+
+static int net_failover_slave_register(struct net_device *slave_dev)
+{
+	struct net_failover_info *nfo_info;
+	struct net_failover_ops *nfo_ops;
+	struct net_device *failover_dev;
+	bool slave_is_standby;
+	u32 orig_mtu;
+	int err;
+
+	ASSERT_RTNL();
+
+	failover_dev = net_failover_get_bymac(slave_dev->perm_addr, &nfo_ops);
+	if (!failover_dev)
+		goto done;
+
+	if (failover_dev->type != slave_dev->type)
+		goto done;
+
+	if (nfo_ops && nfo_ops->slave_register)
+		return nfo_ops->slave_register(slave_dev, failover_dev);
+
+	nfo_info = netdev_priv(failover_dev);
+	slave_is_standby = (slave_dev->dev.parent == failover_dev->dev.parent);
+	if (slave_is_standby ? rtnl_dereference(nfo_info->standby_dev) :
+			rtnl_dereference(nfo_info->primary_dev)) {
+		netdev_err(failover_dev, "%s attempting to register as slave dev when %s already present\n",
+			   slave_dev->name,
+			   slave_is_standby ? "standby" : "primary");
+		goto done;
+	}
+
+	/* We want to allow only a direct attached VF device as a primary
+	 * netdev. As there is no easy way to check for a VF device, restrict
+	 * this to a pci device.
+	 */
+	if (!slave_is_standby && (!slave_dev->dev.parent ||
+				  !dev_is_pci(slave_dev->dev.parent)))
+		goto done;
+
+	if (failover_dev->features & NETIF_F_VLAN_CHALLENGED &&
+	    vlan_uses_dev(failover_dev)) {
+		netdev_err(failover_dev, "Device %s is VLAN challenged and failover device has VLAN set up\n",
+			   failover_dev->name);
+		goto done;
+	}
+
+	/* Align MTU of slave with failover dev */
+	orig_mtu = slave_dev->mtu;
+	err = dev_set_mtu(slave_dev, failover_dev->mtu);
+	if (err) {
+		netdev_err(failover_dev, "unable to change mtu of %s to %u register failed\n",
+			   slave_dev->name, failover_dev->mtu);
+		goto done;
+	}
+
+	dev_hold(slave_dev);
+
+	if (netif_running(failover_dev)) {
+		err = dev_open(slave_dev);
+		if (err && (err != -EBUSY)) {
+			netdev_err(failover_dev, "Opening slave %s failed err:%d\n",
+				   slave_dev->name, err);
+			goto err_dev_open;
+		}
+	}
+
+	netif_addr_lock_bh(failover_dev);
+	dev_uc_sync_multiple(slave_dev, failover_dev);
+	dev_uc_sync_multiple(slave_dev, failover_dev);
+	netif_addr_unlock_bh(failover_dev);
+
+	err = vlan_vids_add_by_dev(slave_dev, failover_dev);
+	if (err) {
+		netdev_err(failover_dev, "Failed to add vlan ids to device %s err:%d\n",
+			   slave_dev->name, err);
+		goto err_vlan_add;
+	}
+
+	err = netdev_rx_handler_register(slave_dev, net_failover_handle_frame,
+					 failover_dev);
+	if (err) {
+		netdev_err(slave_dev, "can not register failover rx handler (err = %d)\n",
+			   err);
+		goto err_handler_register;
+	}
+
+	err = netdev_upper_dev_link(slave_dev, failover_dev, NULL);
+	if (err) {
+		netdev_err(slave_dev, "can not set failover device %s (err = %d)\n",
+			   failover_dev->name, err);
+		goto err_upper_link;
+	}
+
+	slave_dev->priv_flags |= IFF_FAILOVER_SLAVE;
+
+	if (slave_is_standby) {
+		rcu_assign_pointer(nfo_info->standby_dev, slave_dev);
+		dev_get_stats(nfo_info->standby_dev, &nfo_info->standby_stats);
+	} else {
+		rcu_assign_pointer(nfo_info->primary_dev, slave_dev);
+		dev_get_stats(nfo_info->primary_dev, &nfo_info->primary_stats);
+		failover_dev->min_mtu = slave_dev->min_mtu;
+		failover_dev->max_mtu = slave_dev->max_mtu;
+	}
+
+	net_failover_compute_features(failover_dev);
+
+	call_netdevice_notifiers(NETDEV_JOIN, slave_dev);
+
+	netdev_info(failover_dev, "failover %s slave:%s registered\n",
+		    slave_is_standby ? "standby" : "primary", slave_dev->name);
+
+	goto done;
+
+err_upper_link:
+	netdev_rx_handler_unregister(slave_dev);
+err_handler_register:
+	vlan_vids_del_by_dev(slave_dev, failover_dev);
+err_vlan_add:
+	dev_uc_unsync(slave_dev, failover_dev);
+	dev_mc_unsync(slave_dev, failover_dev);
+	dev_close(slave_dev);
+err_dev_open:
+	dev_put(slave_dev);
+	dev_set_mtu(slave_dev, orig_mtu);
+done:
+	return NOTIFY_DONE;
+}
+
+int net_failover_slave_unregister(struct net_device *slave_dev)
+{
+	struct net_device *standby_dev, *primary_dev;
+	struct net_failover_info *nfo_info;
+	struct net_failover_ops *nfo_ops;
+	struct net_device *failover_dev;
+	bool slave_is_standby;
+
+	if (!netif_is_failover_slave(slave_dev))
+		goto done;
+
+	ASSERT_RTNL();
+
+	failover_dev = net_failover_get_bymac(slave_dev->perm_addr, &nfo_ops);
+	if (!failover_dev)
+		goto done;
+
+	if (nfo_ops && nfo_ops->slave_unregister)
+		return nfo_ops->slave_unregister(slave_dev, failover_dev);
+
+	nfo_info = netdev_priv(failover_dev);
+	primary_dev = rtnl_dereference(nfo_info->primary_dev);
+	standby_dev = rtnl_dereference(nfo_info->standby_dev);
+
+	if (slave_dev != primary_dev && slave_dev != standby_dev)
+		goto done;
+
+	slave_is_standby = (slave_dev->dev.parent == failover_dev->dev.parent);
+
+	netdev_rx_handler_unregister(slave_dev);
+	netdev_upper_dev_unlink(slave_dev, failover_dev);
+	vlan_vids_del_by_dev(slave_dev, failover_dev);
+	dev_uc_unsync(slave_dev, failover_dev);
+	dev_mc_unsync(slave_dev, failover_dev);
+	dev_close(slave_dev);
+	slave_dev->priv_flags &= ~IFF_FAILOVER_SLAVE;
+
+	nfo_info = netdev_priv(failover_dev);
+	net_failover_get_stats(failover_dev, &nfo_info->failover_stats);
+
+	if (slave_is_standby) {
+		RCU_INIT_POINTER(nfo_info->standby_dev, NULL);
+	} else {
+		RCU_INIT_POINTER(nfo_info->primary_dev, NULL);
+		if (standby_dev) {
+			failover_dev->min_mtu = standby_dev->min_mtu;
+			failover_dev->max_mtu = standby_dev->max_mtu;
+		}
+	}
+
+	dev_put(slave_dev);
+
+	net_failover_compute_features(failover_dev);
+
+	netdev_info(failover_dev, "failover %s slave:%s unregistered\n",
+		    slave_is_standby ? "standby" : "primary", slave_dev->name);
+
+done:
+	return NOTIFY_DONE;
+}
+EXPORT_SYMBOL_GPL(net_failover_slave_unregister);
+
+static int net_failover_slave_link_change(struct net_device *slave_dev)
+{
+	struct net_device *failover_dev, *primary_dev, *standby_dev;
+	struct net_failover_info *nfo_info;
+	struct net_failover_ops *nfo_ops;
+
+	if (!netif_is_failover_slave(slave_dev))
+		goto done;
+
+	ASSERT_RTNL();
+
+	failover_dev = net_failover_get_bymac(slave_dev->perm_addr, &nfo_ops);
+	if (!failover_dev)
+		goto done;
+
+	if (nfo_ops && nfo_ops->slave_link_change)
+		return nfo_ops->slave_link_change(slave_dev, failover_dev);
+
+	if (!netif_running(failover_dev))
+		return 0;
+
+	nfo_info = netdev_priv(failover_dev);
+
+	primary_dev = rtnl_dereference(nfo_info->primary_dev);
+	standby_dev = rtnl_dereference(nfo_info->standby_dev);
+
+	if (slave_dev != primary_dev && slave_dev != standby_dev)
+		goto done;
+
+	if ((primary_dev && net_failover_xmit_ready(primary_dev)) ||
+	    (standby_dev && net_failover_xmit_ready(standby_dev))) {
+		netif_carrier_on(failover_dev);
+		netif_tx_wake_all_queues(failover_dev);
+	} else {
+		net_failover_get_stats(failover_dev, &nfo_info->failover_stats);
+		netif_carrier_off(failover_dev);
+		netif_tx_stop_all_queues(failover_dev);
+	}
+
+done:
+	return NOTIFY_DONE;
+}
+
+static int
+net_failover_event(struct notifier_block *this, unsigned long event, void *ptr)
+{
+	struct net_device *event_dev = netdev_notifier_info_to_dev(ptr);
+
+	/* Skip parent events */
+	if (netif_is_failover(event_dev))
+		return NOTIFY_DONE;
+
+	switch (event) {
+	case NETDEV_REGISTER:
+		return net_failover_slave_register(event_dev);
+	case NETDEV_UNREGISTER:
+		return net_failover_slave_unregister(event_dev);
+	case NETDEV_UP:
+	case NETDEV_DOWN:
+	case NETDEV_CHANGE:
+		return net_failover_slave_link_change(event_dev);
+	default:
+		return NOTIFY_DONE;
+	}
+}
+
+static struct notifier_block net_failover_notifier = {
+	.notifier_call = net_failover_event,
+};
+
+static void nfo_register_existing_slave(struct net_device *failover_dev)
+{
+	struct net *net = dev_net(failover_dev);
+	struct net_device *dev;
+
+	rtnl_lock();
+	for_each_netdev(net, dev) {
+		if (netif_is_failover(dev))
+			continue;
+		if (ether_addr_equal(failover_dev->perm_addr, dev->perm_addr))
+			net_failover_slave_register(dev);
+	}
+	rtnl_unlock();
+}
+
+int net_failover_register(struct net_device *dev, struct net_failover_ops *ops,
+			  struct net_failover **pfailover)
+{
+	struct net_failover *failover;
+
+	failover = kzalloc(sizeof(*failover), GFP_KERNEL);
+	if (!failover)
+		return -ENOMEM;
+
+	rcu_assign_pointer(failover->ops, ops);
+	dev_hold(dev);
+	dev->priv_flags |= IFF_FAILOVER;
+	rcu_assign_pointer(failover->failover_dev, dev);
+
+	spin_lock(&net_failover_lock);
+	list_add_tail(&failover->list, &net_failover_list);
+	spin_unlock(&net_failover_lock);
+
+	netdev_info(dev, "failover master:%s registered\n", dev->name);
+
+	nfo_register_existing_slave(dev);
+
+	*pfailover = failover;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(net_failover_register);
+
+void net_failover_unregister(struct net_failover *failover)
+{
+	struct net_device *failover_dev;
+
+	failover_dev = rcu_dereference(failover->failover_dev);
+
+	netdev_info(failover_dev, "failover master:%s unregistered\n",
+		    failover_dev->name);
+
+	failover_dev->priv_flags &= ~IFF_FAILOVER;
+	dev_put(failover_dev);
+
+	spin_lock(&net_failover_lock);
+	list_del(&failover->list);
+	spin_unlock(&net_failover_lock);
+
+	kfree(failover);
+}
+EXPORT_SYMBOL_GPL(net_failover_unregister);
+
+int net_failover_create(struct net_device *standby_dev,
+			struct net_failover **pfailover)
+{
+	struct device *dev = standby_dev->dev.parent;
+	struct net_device *failover_dev;
+	int err;
+
+	/* Alloc at least 2 queues, for now we are going with 16 assuming
+	 * that VF devices being enslaved won't have too many queues.
+	 */
+	failover_dev = alloc_etherdev_mq(sizeof(struct net_failover_info), 16);
+	if (!failover_dev) {
+		dev_err(dev, "Unable to allocate failover_netdev!\n");
+		return -ENOMEM;
+	}
+
+	dev_net_set(failover_dev, dev_net(standby_dev));
+	SET_NETDEV_DEV(failover_dev, dev);
+
+	failover_dev->netdev_ops = &failover_dev_ops;
+	failover_dev->ethtool_ops = &failover_ethtool_ops;
+
+	/* Initialize the device options */
+	failover_dev->priv_flags |= IFF_UNICAST_FLT | IFF_NO_QUEUE;
+	failover_dev->priv_flags &= ~(IFF_XMIT_DST_RELEASE |
+				       IFF_TX_SKB_SHARING);
+
+	/* don't acquire failover netdev's netif_tx_lock when transmitting */
+	failover_dev->features |= NETIF_F_LLTX;
+
+	/* Don't allow failover devices to change network namespaces. */
+	failover_dev->features |= NETIF_F_NETNS_LOCAL;
+
+	failover_dev->hw_features = FAILOVER_VLAN_FEATURES |
+				    NETIF_F_HW_VLAN_CTAG_TX |
+				    NETIF_F_HW_VLAN_CTAG_RX |
+				    NETIF_F_HW_VLAN_CTAG_FILTER;
+
+	failover_dev->hw_features |= NETIF_F_GSO_ENCAP_ALL;
+	failover_dev->features |= failover_dev->hw_features;
+
+	memcpy(failover_dev->dev_addr, standby_dev->dev_addr,
+	       failover_dev->addr_len);
+
+	failover_dev->min_mtu = standby_dev->min_mtu;
+	failover_dev->max_mtu = standby_dev->max_mtu;
+
+	err = register_netdev(failover_dev);
+	if (err < 0) {
+		dev_err(dev, "Unable to register failover_dev!\n");
+		goto err_register_netdev;
+	}
+
+	netif_carrier_off(failover_dev);
+
+	err = net_failover_register(failover_dev, NULL, pfailover);
+	if (err < 0)
+		goto err_failover_register;
+
+	return 0;
+
+err_failover_register:
+	unregister_netdev(failover_dev);
+err_register_netdev:
+	free_netdev(failover_dev);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(net_failover_create);
+
+void net_failover_destroy(struct net_failover *failover)
+{
+	struct net_failover_info *nfo_info;
+	struct net_device *failover_dev;
+	struct net_device *slave_dev;
+
+	if (!failover)
+		return;
+
+	failover_dev = rcu_dereference(failover->failover_dev);
+	nfo_info = netdev_priv(failover_dev);
+
+	netif_device_detach(failover_dev);
+
+	rtnl_lock();
+
+	slave_dev = rtnl_dereference(nfo_info->primary_dev);
+	if (slave_dev)
+		net_failover_slave_unregister(slave_dev);
+
+	slave_dev = rtnl_dereference(nfo_info->standby_dev);
+	if (slave_dev)
+		net_failover_slave_unregister(slave_dev);
+
+	net_failover_unregister(failover);
+
+	unregister_netdevice(failover_dev);
+
+	rtnl_unlock();
+
+	free_netdev(failover_dev);
+}
+EXPORT_SYMBOL_GPL(net_failover_destroy);
+
+static __init int
+net_failover_init(void)
+{
+	register_netdevice_notifier(&net_failover_notifier);
+
+	return 0;
+}
+module_init(net_failover_init);
+
+static __exit
+void net_failover_exit(void)
+{
+	unregister_netdevice_notifier(&net_failover_notifier);
+}
+module_exit(net_failover_exit);
+
+MODULE_DESCRIPTION("Failover infrastructure/interface for Paravirtual drivers");
+MODULE_LICENSE("GPL v2");
-- 
2.14.3

[PATCH net-next v8 3/4] virtio_net: Extend virtio to use VF datapath when available

[Sridhar Samudrala]

This patch enables virtio_net to switch over to a VF datapath when a VF
netdev is present with the same MAC address. It allows live migration
of a VM with a direct attached VF without the need to setup a bond/team
between a VF and virtio net device in the guest.

The hypervisor needs to enable only one datapath at any time so that
packets don't get looped back to the VM over the other datapath. When a VF
is plugged, the virtio datapath link state can be marked as down. The
hypervisor needs to unplug the VF device from the guest on the source host
and reset the MAC filter of the VF to initiate failover of datapath to
virtio before starting the migration. After the migration is completed,
the destination hypervisor sets the MAC filter on the VF and plugs it back
to the guest to switch over to VF datapath.

It uses the generic failover framework that provides 2 functions to create
and destroy a master failover netdev. When STANDBY feature is enabled, an
additional netdev(failover netdev) is created that acts as a master device
and tracks the state of the 2 lower netdevs. The original virtio_net netdev
is marked as 'standby' netdev and a passthru device with the same MAC is
registered as 'primary' netdev.

This patch is based on the discussion initiated by Jesse on this thread.
https://marc.info/?l=linux-virtualization&m=151189725224231&w=2

Signed-off-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
---
 drivers/net/Kconfig      |  1 +
 drivers/net/virtio_net.c | 35 ++++++++++++++++++++++++++++++++++-
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 891846655000..5233e94ea37e 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -331,6 +331,7 @@ config VETH
 config VIRTIO_NET
 	tristate "Virtio network driver"
 	depends on VIRTIO
+	depends on MAY_USE_NET_FAILOVER
 	---help---
 	  This is the virtual network driver for virtio.  It can be used with
 	  QEMU based VMMs (like KVM or Xen).  Say Y or M.
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 51a085b1a242..c326ee5344c0 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -30,8 +30,11 @@
 #include <linux/cpu.h>
 #include <linux/average.h>
 #include <linux/filter.h>
+#include <linux/netdevice.h>
+#include <linux/pci.h>
 #include <net/route.h>
 #include <net/xdp.h>
+#include <net/net_failover.h>
 
 static int napi_weight = NAPI_POLL_WEIGHT;
 module_param(napi_weight, int, 0444);
@@ -210,6 +213,9 @@ struct virtnet_info {
 	u32 speed;
 
 	unsigned long guest_offloads;
+
+	/* failover when STANDBY feature enabled */
+	struct net_failover *failover;
 };
 
 struct padded_vnet_hdr {
@@ -2306,6 +2312,22 @@ static int virtnet_xdp(struct net_device *dev, struct netdev_bpf *xdp)
 	}
 }
 
+static int virtnet_get_phys_port_name(struct net_device *dev, char *buf,
+				      size_t len)
+{
+	struct virtnet_info *vi = netdev_priv(dev);
+	int ret;
+
+	if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_STANDBY))
+		return -EOPNOTSUPP;
+
+	ret = snprintf(buf, len, "_sby");
+	if (ret >= len)
+		return -EOPNOTSUPP;
+
+	return 0;
+}
+
 static const struct net_device_ops virtnet_netdev = {
 	.ndo_open            = virtnet_open,
 	.ndo_stop   	     = virtnet_close,
@@ -2323,6 +2345,7 @@ static const struct net_device_ops virtnet_netdev = {
 	.ndo_xdp_xmit		= virtnet_xdp_xmit,
 	.ndo_xdp_flush		= virtnet_xdp_flush,
 	.ndo_features_check	= passthru_features_check,
+	.ndo_get_phys_port_name	= virtnet_get_phys_port_name,
 };
 
 static void virtnet_config_changed_work(struct work_struct *work)
@@ -2876,10 +2899,16 @@ static int virtnet_probe(struct virtio_device *vdev)
 
 	virtnet_init_settings(dev);
 
+	if (virtio_has_feature(vdev, VIRTIO_NET_F_STANDBY)) {
+		err = net_failover_create(vi->dev, &vi->failover);
+		if (err)
+			goto free_vqs;
+	}
+
 	err = register_netdev(dev);
 	if (err) {
 		pr_debug("virtio_net: registering device failed\n");
-		goto free_vqs;
+		goto free_failover;
 	}
 
 	virtio_device_ready(vdev);
@@ -2916,6 +2945,8 @@ static int virtnet_probe(struct virtio_device *vdev)
 	vi->vdev->config->reset(vdev);
 
 	unregister_netdev(dev);
+free_failover:
+	net_failover_destroy(vi->failover);
 free_vqs:
 	cancel_delayed_work_sync(&vi->refill);
 	free_receive_page_frags(vi);
@@ -2950,6 +2981,8 @@ static void virtnet_remove(struct virtio_device *vdev)
 
 	unregister_netdev(vi->dev);
 
+	net_failover_destroy(vi->failover);
+
 	remove_vq_common(vi);
 
 	free_netdev(vi->dev);
-- 
2.14.3

[PATCH net-next v8 4/4] netvsc: refactor notifier/event handling code to use the failover framework

[Sridhar Samudrala]

Use the registration/notification framework supported by the generic
failover infrastructure.

Signed-off-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
---
 drivers/net/hyperv/Kconfig      |   1 +
 drivers/net/hyperv/hyperv_net.h |   2 +
 drivers/net/hyperv/netvsc_drv.c | 134 +++++++---------------------------------
 3 files changed, 26 insertions(+), 111 deletions(-)

diff --git a/drivers/net/hyperv/Kconfig b/drivers/net/hyperv/Kconfig
index 0765d5f61714..20e70d4855a9 100644
--- a/drivers/net/hyperv/Kconfig
+++ b/drivers/net/hyperv/Kconfig
@@ -1,6 +1,7 @@
 config HYPERV_NET
 	tristate "Microsoft Hyper-V virtual network driver"
 	depends on HYPERV
+	depends on MAY_USE_NET_FAILOVER
 	select UCS2_STRING
 	help
 	  Select this option to enable the Hyper-V virtual network driver.
diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index 6ebe39a3dde6..2ec18344c0e8 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -932,6 +932,8 @@ struct net_device_context {
 	u32 vf_alloc;
 	/* Serial number of the VF to team with */
 	u32 vf_serial;
+
+	struct net_failover *failover;
 };
 
 /* Per channel data */
diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index ecc84954c511..fa446234bc11 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -43,6 +43,7 @@
 #include <net/pkt_sched.h>
 #include <net/checksum.h>
 #include <net/ip6_checksum.h>
+#include <net/net_failover.h>
 
 #include "hyperv_net.h"
 
@@ -1763,46 +1764,6 @@ static void netvsc_link_change(struct work_struct *w)
 	rtnl_unlock();
 }
 
-static struct net_device *get_netvsc_bymac(const u8 *mac)
-{
-	struct net_device *dev;
-
-	ASSERT_RTNL();
-
-	for_each_netdev(&init_net, dev) {
-		if (dev->netdev_ops != &device_ops)
-			continue;	/* not a netvsc device */
-
-		if (ether_addr_equal(mac, dev->perm_addr))
-			return dev;
-	}
-
-	return NULL;
-}
-
-static struct net_device *get_netvsc_byref(struct net_device *vf_netdev)
-{
-	struct net_device *dev;
-
-	ASSERT_RTNL();
-
-	for_each_netdev(&init_net, dev) {
-		struct net_device_context *net_device_ctx;
-
-		if (dev->netdev_ops != &device_ops)
-			continue;	/* not a netvsc device */
-
-		net_device_ctx = netdev_priv(dev);
-		if (!rtnl_dereference(net_device_ctx->nvdev))
-			continue;	/* device is removed */
-
-		if (rtnl_dereference(net_device_ctx->vf_netdev) == vf_netdev)
-			return dev;	/* a match */
-	}
-
-	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
@@ -1914,24 +1875,15 @@ static void netvsc_vf_setup(struct work_struct *w)
 	rtnl_unlock();
 }
 
-static int netvsc_register_vf(struct net_device *vf_netdev)
+static int netvsc_register_vf(struct net_device *vf_netdev,
+			      struct net_device *ndev)
 {
-	struct net_device *ndev;
 	struct net_device_context *net_device_ctx;
 	struct netvsc_device *netvsc_dev;
 
 	if (vf_netdev->addr_len != ETH_ALEN)
 		return NOTIFY_DONE;
 
-	/*
-	 * We will use the MAC address to locate the synthetic interface to
-	 * associate with the VF interface. If we don't find a matching
-	 * synthetic interface, move on.
-	 */
-	ndev = get_netvsc_bymac(vf_netdev->perm_addr);
-	if (!ndev)
-		return NOTIFY_DONE;
-
 	net_device_ctx = netdev_priv(ndev);
 	netvsc_dev = rtnl_dereference(net_device_ctx->nvdev);
 	if (!netvsc_dev || rtnl_dereference(net_device_ctx->vf_netdev))
@@ -1948,17 +1900,13 @@ static int netvsc_register_vf(struct net_device *vf_netdev)
 }
 
 /* VF up/down change detected, schedule to change data path */
-static int netvsc_vf_changed(struct net_device *vf_netdev)
+static int netvsc_vf_changed(struct net_device *vf_netdev,
+			     struct net_device *ndev)
 {
 	struct net_device_context *net_device_ctx;
 	struct netvsc_device *netvsc_dev;
-	struct net_device *ndev;
 	bool vf_is_up = netif_running(vf_netdev);
 
-	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);
 	if (!netvsc_dev)
@@ -1971,15 +1919,11 @@ static int netvsc_vf_changed(struct net_device *vf_netdev)
 	return NOTIFY_OK;
 }
 
-static int netvsc_unregister_vf(struct net_device *vf_netdev)
+static int netvsc_unregister_vf(struct net_device *vf_netdev,
+				struct net_device *ndev)
 {
-	struct net_device *ndev;
 	struct net_device_context *net_device_ctx;
 
-	ndev = get_netvsc_byref(vf_netdev);
-	if (!ndev)
-		return NOTIFY_DONE;
-
 	net_device_ctx = netdev_priv(ndev);
 	cancel_delayed_work_sync(&net_device_ctx->vf_takeover);
 
@@ -1993,6 +1937,12 @@ static int netvsc_unregister_vf(struct net_device *vf_netdev)
 	return NOTIFY_OK;
 }
 
+static struct net_failover_ops netvsc_failover_ops = {
+	.slave_register		= netvsc_register_vf,
+	.slave_unregister	= netvsc_unregister_vf,
+	.slave_link_change	= netvsc_vf_changed,
+};
+
 static int netvsc_probe(struct hv_device *dev,
 			const struct hv_vmbus_device_id *dev_id)
 {
@@ -2082,8 +2032,15 @@ static int netvsc_probe(struct hv_device *dev,
 		goto register_failed;
 	}
 
+	ret = net_failover_register(net, &netvsc_failover_ops,
+				    &net_device_ctx->failover);
+	if (ret != 0)
+		goto err_failover;
+
 	return ret;
 
+err_failover:
+	unregister_netdev(net);
 register_failed:
 	rndis_filter_device_remove(dev, nvdev);
 rndis_failed:
@@ -2124,13 +2081,15 @@ static int netvsc_remove(struct hv_device *dev)
 	rtnl_lock();
 	vf_netdev = rtnl_dereference(ndev_ctx->vf_netdev);
 	if (vf_netdev)
-		netvsc_unregister_vf(vf_netdev);
+		net_failover_slave_unregister(vf_netdev);
 
 	if (nvdev)
 		rndis_filter_device_remove(dev, nvdev);
 
 	unregister_netdevice(net);
 
+	net_failover_unregister(ndev_ctx->failover);
+
 	rtnl_unlock();
 	rcu_read_unlock();
 
@@ -2157,54 +2116,8 @@ static struct  hv_driver netvsc_drv = {
 	.remove = netvsc_remove,
 };
 
-/*
- * On Hyper-V, every VF interface is matched with a corresponding
- * synthetic interface. The synthetic interface is presented first
- * to the guest. When the corresponding VF instance is registered,
- * we will take care of switching the data path.
- */
-static int netvsc_netdev_event(struct notifier_block *this,
-			       unsigned long event, void *ptr)
-{
-	struct net_device *event_dev = netdev_notifier_info_to_dev(ptr);
-
-	/* Skip our own events */
-	if (event_dev->netdev_ops == &device_ops)
-		return NOTIFY_DONE;
-
-	/* Avoid non-Ethernet type devices */
-	if (event_dev->type != ARPHRD_ETHER)
-		return NOTIFY_DONE;
-
-	/* Avoid Vlan dev with same MAC registering as VF */
-	if (is_vlan_dev(event_dev))
-		return NOTIFY_DONE;
-
-	/* Avoid Bonding master dev with same MAC registering as VF */
-	if ((event_dev->priv_flags & IFF_BONDING) &&
-	    (event_dev->flags & IFF_MASTER))
-		return NOTIFY_DONE;
-
-	switch (event) {
-	case NETDEV_REGISTER:
-		return netvsc_register_vf(event_dev);
-	case NETDEV_UNREGISTER:
-		return netvsc_unregister_vf(event_dev);
-	case NETDEV_UP:
-	case NETDEV_DOWN:
-		return netvsc_vf_changed(event_dev);
-	default:
-		return NOTIFY_DONE;
-	}
-}
-
-static struct notifier_block netvsc_netdev_notifier = {
-	.notifier_call = netvsc_netdev_event,
-};
-
 static void __exit netvsc_drv_exit(void)
 {
-	unregister_netdevice_notifier(&netvsc_netdev_notifier);
 	vmbus_driver_unregister(&netvsc_drv);
 }
 
@@ -2224,7 +2137,6 @@ static int __init netvsc_drv_init(void)
 	if (ret)
 		return ret;
 
-	register_netdevice_notifier(&netvsc_netdev_notifier);
 	return 0;
 }
 
-- 
2.14.3

Re: [PATCH net-next v8 4/4] netvsc: refactor notifier/event handling code to use the failover framework

[Stephen Hemminger]

On Wed, 25 Apr 2018 16:59:28 -0700
Sridhar Samudrala <sridhar.samudrala@intel.com> wrote:

> Use the registration/notification framework supported by the generic
> failover infrastructure.
> 
> Signed-off-by: Sridhar Samudrala <sridhar.samudrala@intel.com>

NAK unless you prove this works on legacy distributions and with DPDK 18.05
without modification.
 

Re: [PATCH net-next v8 4/4] netvsc: refactor notifier/event handling code to use the failover framework

[Michael S. Tsirkin]

On Wed, Apr 25, 2018 at 05:08:37PM -0700, Stephen Hemminger wrote:
> On Wed, 25 Apr 2018 16:59:28 -0700
> Sridhar Samudrala <sridhar.samudrala@intel.com> wrote:
> 
> > Use the registration/notification framework supported by the generic
> > failover infrastructure.
> > 
> > Signed-off-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
> 
> NAK unless you prove this works on legacy distributions and with DPDK 18.05
> without modification.

It looks like it should work. What kind of proof are you looking for?

-- 
MST

Re: [PATCH net-next v8 4/4] netvsc: refactor notifier/event handling code to use the failover framework

[Stephen Hemminger]

On Thu, 26 Apr 2018 05:30:05 +0300
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> On Wed, Apr 25, 2018 at 05:08:37PM -0700, Stephen Hemminger wrote:
> > On Wed, 25 Apr 2018 16:59:28 -0700
> > Sridhar Samudrala <sridhar.samudrala@intel.com> wrote:
> >   
> > > Use the registration/notification framework supported by the generic
> > > failover infrastructure.
> > > 
> > > Signed-off-by: Sridhar Samudrala <sridhar.samudrala@intel.com>  
> > 
> > NAK unless you prove this works on legacy distributions and with DPDK 18.05
> > without modification.  
> 
> It looks like it should work. What kind of proof are you looking for?
> 


I tried this with working Ubuntu 17 on WS2016.
It boots if the failover driver is configured in (as module).
But if the configuration has:

$ grep FAILOVER .config
# CONFIG_NET_FAILOVER is not set
CONFIG_MAY_USE_NET_FAILOVER=y


The netvsc driver fails on boot with:

[    0.826447] hv_vmbus: registering driver hv_netvsc
[    0.829616] scsi 0:0:0:0: Direct-Access     Msft     Virtual Disk     1.0  PQ: 0 ANSI: 5
[    0.836291] input: Microsoft Vmbus HID-compliant Mouse as /devices/0006:045E:0621.0001/input/input1
[    0.839139] hid-generic 0006:045E:0621.0001: input: <UNKNOWN> HID v0.01 Mouse [Microsoft Vmbus HID-compliant Mouse] on
[    0.964897] hv_vmbus: probe failed for device 849a776e-8120-4e4a-9a36-7e3d95ac75b3 (-95)
[    0.968039] hv_netvsc: probe of 849a776e-8120-4e4a-9a36-7e3d95ac75b3 failed with error -95
[    1.112877] hv_vmbus: probe failed for device 53557f8e-057d-425b-9265-01c0fd7e273e (-95)
[    1.116064] hv_netvsc: probe of 53557f8e-057d-425b-9265-01c0fd7e273e failed with error -95

The system has two virtual networks. eth0 is on vswitch for management.
eth1 is on vswitch with SR-IOV for performance tests.

You probably need to just put the failover part in net/core and select it.


It is trivial to get an evaluation version of Windows Server 2016 and setup a Linux VM.
Please try it.

Re: [PATCH net-next v8 4/4] netvsc: refactor notifier/event handling code to use the failover framework

[Michael S. Tsirkin]

On Thu, Apr 26, 2018 at 03:33:26PM -0700, Stephen Hemminger wrote:
> On Thu, 26 Apr 2018 05:30:05 +0300
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
> 
> > On Wed, Apr 25, 2018 at 05:08:37PM -0700, Stephen Hemminger wrote:
> > > On Wed, 25 Apr 2018 16:59:28 -0700
> > > Sridhar Samudrala <sridhar.samudrala@intel.com> wrote:
> > >   
> > > > Use the registration/notification framework supported by the generic
> > > > failover infrastructure.
> > > > 
> > > > Signed-off-by: Sridhar Samudrala <sridhar.samudrala@intel.com>  
> > > 
> > > NAK unless you prove this works on legacy distributions and with DPDK 18.05
> > > without modification.  
> > 
> > It looks like it should work. What kind of proof are you looking for?
> > 
> 
> 
> I tried this with working Ubuntu 17 on WS2016.
> It boots if the failover driver is configured in (as module).

Oh so by "unless you prove" you meant "unless you test"?

> But if the configuration has:
> 
> $ grep FAILOVER .config
> # CONFIG_NET_FAILOVER is not set
> CONFIG_MAY_USE_NET_FAILOVER=y

So the new option works, what's broken is when it's *not* selected.
Looks like a bug.

> The netvsc driver fails on boot with:
> 
> [    0.826447] hv_vmbus: registering driver hv_netvsc
> [    0.829616] scsi 0:0:0:0: Direct-Access     Msft     Virtual Disk     1.0  PQ: 0 ANSI: 5
> [    0.836291] input: Microsoft Vmbus HID-compliant Mouse as /devices/0006:045E:0621.0001/input/input1
> [    0.839139] hid-generic 0006:045E:0621.0001: input: <UNKNOWN> HID v0.01 Mouse [Microsoft Vmbus HID-compliant Mouse] on
> [    0.964897] hv_vmbus: probe failed for device 849a776e-8120-4e4a-9a36-7e3d95ac75b3 (-95)
> [    0.968039] hv_netvsc: probe of 849a776e-8120-4e4a-9a36-7e3d95ac75b3 failed with error -95
> [    1.112877] hv_vmbus: probe failed for device 53557f8e-057d-425b-9265-01c0fd7e273e (-95)
> [    1.116064] hv_netvsc: probe of 53557f8e-057d-425b-9265-01c0fd7e273e failed with error -95
> 
> The system has two virtual networks. eth0 is on vswitch for management.
> eth1 is on vswitch with SR-IOV for performance tests.
> 
> You probably need to just put the failover part in net/core and select it.

>From all drivers. Yes. And it does not need to be visible in the menu
imho.


> It is trivial to get an evaluation version of Windows Server 2016 and setup a Linux VM.
> Please try it.

I presume some kind of test was done here. Sridhar, do you think you
could include some notes about testing of this patch? Or in case you
only build-tested this part, it's a good idea to notice this after ---
in the patch, or in the cover letter.

-- 
MST

Re: [PATCH net-next v8 4/4] netvsc: refactor notifier/event handling code to use the failover framework

[Samudrala, Sridhar]

On 4/26/2018 5:09 PM, Michael S. Tsirkin wrote:
> On Thu, Apr 26, 2018 at 03:33:26PM -0700, Stephen Hemminger wrote:
>> On Thu, 26 Apr 2018 05:30:05 +0300
>> "Michael S. Tsirkin" <mst@redhat.com> wrote:
>>
>>> On Wed, Apr 25, 2018 at 05:08:37PM -0700, Stephen Hemminger wrote:
>>>> On Wed, 25 Apr 2018 16:59:28 -0700
>>>> Sridhar Samudrala <sridhar.samudrala@intel.com> wrote:
>>>>    
>>>>> Use the registration/notification framework supported by the generic
>>>>> failover infrastructure.
>>>>>
>>>>> Signed-off-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
>>>> NAK unless you prove this works on legacy distributions and with DPDK 18.05
>>>> without modification.
>>> It looks like it should work. What kind of proof are you looking for?
>>>
>>
>> I tried this with working Ubuntu 17 on WS2016.
>> It boots if the failover driver is configured in (as module).
> Oh so by "unless you prove" you meant "unless you test"?
>
>> But if the configuration has:
>>
>> $ grep FAILOVER .config
>> # CONFIG_NET_FAILOVER is not set
>> CONFIG_MAY_USE_NET_FAILOVER=y
> So the new option works, what's broken is when it's *not* selected.
> Looks like a bug.

Yes.  Looks like i need to make NET_FAILOVER  to be enabled automatically when
VIRTIO_NET or HYPERV_NET are selected.

Thanks Stephen for confirming that it works when NET_FAILOVER is enabled.



>
>> The netvsc driver fails on boot with:
>>
>> [    0.826447] hv_vmbus: registering driver hv_netvsc
>> [    0.829616] scsi 0:0:0:0: Direct-Access     Msft     Virtual Disk     1.0  PQ: 0 ANSI: 5
>> [    0.836291] input: Microsoft Vmbus HID-compliant Mouse as /devices/0006:045E:0621.0001/input/input1
>> [    0.839139] hid-generic 0006:045E:0621.0001: input: <UNKNOWN> HID v0.01 Mouse [Microsoft Vmbus HID-compliant Mouse] on
>> [    0.964897] hv_vmbus: probe failed for device 849a776e-8120-4e4a-9a36-7e3d95ac75b3 (-95)
>> [    0.968039] hv_netvsc: probe of 849a776e-8120-4e4a-9a36-7e3d95ac75b3 failed with error -95
>> [    1.112877] hv_vmbus: probe failed for device 53557f8e-057d-425b-9265-01c0fd7e273e (-95)
>> [    1.116064] hv_netvsc: probe of 53557f8e-057d-425b-9265-01c0fd7e273e failed with error -95
>>
>> The system has two virtual networks. eth0 is on vswitch for management.
>> eth1 is on vswitch with SR-IOV for performance tests.
>>
>> You probably need to just put the failover part in net/core and select it.
>  From all drivers. Yes. And it does not need to be visible in the menu
> imho.
>
>
>> It is trivial to get an evaluation version of Windows Server 2016 and setup a Linux VM.
>> Please try it.
> I presume some kind of test was done here. Sridhar, do you think you
> could include some notes about testing of this patch? Or in case you
> only build-tested this part, it's a good idea to notice this after ---
> in the patch, or in the cover letter.

I only did compile and build test of netvsc. I don't have a hyperv setup to test it out.
Would appreciate if Stephen or someone who has this setup will test it out when i
submit the next revision with the config fixes.

>

Re: [PATCH net-next v8 2/4] net: Introduce generic failover module

[kbuild test robot]

Hi Sridhar,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on net-next/master]

url:    https://github.com/0day-ci/linux/commits/Sridhar-Samudrala/Enable-virtio_net-to-act-as-a-standby-for-a-passthru-device/20180427-183842
reproduce:
        # apt-get install sparse
        make ARCH=x86_64 allmodconfig
        make C=1 CF=-D__CHECK_ENDIAN__


sparse warnings: (new ones prefixed by >>)

>> net/core/net_failover.c:544:39: sparse: incorrect type in argument 1 (different address spaces) @@    expected struct net_device *dev @@    got struct net_devicestruct net_device *dev @@
   net/core/net_failover.c:544:39:    expected struct net_device *dev
   net/core/net_failover.c:544:39:    got struct net_device [noderef] <asn:4>*standby_dev
   net/core/net_failover.c:547:39: sparse: incorrect type in argument 1 (different address spaces) @@    expected struct net_device *dev @@    got struct net_devicestruct net_device *dev @@
   net/core/net_failover.c:547:39:    expected struct net_device *dev
   net/core/net_failover.c:547:39:    got struct net_device [noderef] <asn:4>*primary_dev
>> net/core/net_failover.c:112:12: sparse: context imbalance in 'net_failover_select_queue' - wrong count at exit

vim +544 net/core/net_failover.c

   446	
   447	static int net_failover_slave_register(struct net_device *slave_dev)
   448	{
   449		struct net_failover_info *nfo_info;
   450		struct net_failover_ops *nfo_ops;
   451		struct net_device *failover_dev;
   452		bool slave_is_standby;
   453		u32 orig_mtu;
   454		int err;
   455	
   456		ASSERT_RTNL();
   457	
   458		failover_dev = net_failover_get_bymac(slave_dev->perm_addr, &nfo_ops);
   459		if (!failover_dev)
   460			goto done;
   461	
   462		if (failover_dev->type != slave_dev->type)
   463			goto done;
   464	
   465		if (nfo_ops && nfo_ops->slave_register)
   466			return nfo_ops->slave_register(slave_dev, failover_dev);
   467	
   468		nfo_info = netdev_priv(failover_dev);
   469		slave_is_standby = (slave_dev->dev.parent == failover_dev->dev.parent);
   470		if (slave_is_standby ? rtnl_dereference(nfo_info->standby_dev) :
   471				rtnl_dereference(nfo_info->primary_dev)) {
   472			netdev_err(failover_dev, "%s attempting to register as slave dev when %s already present\n",
   473				   slave_dev->name,
   474				   slave_is_standby ? "standby" : "primary");
   475			goto done;
   476		}
   477	
   478		/* We want to allow only a direct attached VF device as a primary
   479		 * netdev. As there is no easy way to check for a VF device, restrict
   480		 * this to a pci device.
   481		 */
   482		if (!slave_is_standby && (!slave_dev->dev.parent ||
   483					  !dev_is_pci(slave_dev->dev.parent)))
   484			goto done;
   485	
   486		if (failover_dev->features & NETIF_F_VLAN_CHALLENGED &&
   487		    vlan_uses_dev(failover_dev)) {
   488			netdev_err(failover_dev, "Device %s is VLAN challenged and failover device has VLAN set up\n",
   489				   failover_dev->name);
   490			goto done;
   491		}
   492	
   493		/* Align MTU of slave with failover dev */
   494		orig_mtu = slave_dev->mtu;
   495		err = dev_set_mtu(slave_dev, failover_dev->mtu);
   496		if (err) {
   497			netdev_err(failover_dev, "unable to change mtu of %s to %u register failed\n",
   498				   slave_dev->name, failover_dev->mtu);
   499			goto done;
   500		}
   501	
   502		dev_hold(slave_dev);
   503	
   504		if (netif_running(failover_dev)) {
   505			err = dev_open(slave_dev);
   506			if (err && (err != -EBUSY)) {
   507				netdev_err(failover_dev, "Opening slave %s failed err:%d\n",
   508					   slave_dev->name, err);
   509				goto err_dev_open;
   510			}
   511		}
   512	
   513		netif_addr_lock_bh(failover_dev);
   514		dev_uc_sync_multiple(slave_dev, failover_dev);
   515		dev_uc_sync_multiple(slave_dev, failover_dev);
   516		netif_addr_unlock_bh(failover_dev);
   517	
   518		err = vlan_vids_add_by_dev(slave_dev, failover_dev);
   519		if (err) {
   520			netdev_err(failover_dev, "Failed to add vlan ids to device %s err:%d\n",
   521				   slave_dev->name, err);
   522			goto err_vlan_add;
   523		}
   524	
   525		err = netdev_rx_handler_register(slave_dev, net_failover_handle_frame,
   526						 failover_dev);
   527		if (err) {
   528			netdev_err(slave_dev, "can not register failover rx handler (err = %d)\n",
   529				   err);
   530			goto err_handler_register;
   531		}
   532	
   533		err = netdev_upper_dev_link(slave_dev, failover_dev, NULL);
   534		if (err) {
   535			netdev_err(slave_dev, "can not set failover device %s (err = %d)\n",
   536				   failover_dev->name, err);
   537			goto err_upper_link;
   538		}
   539	
   540		slave_dev->priv_flags |= IFF_FAILOVER_SLAVE;
   541	
   542		if (slave_is_standby) {
   543			rcu_assign_pointer(nfo_info->standby_dev, slave_dev);
 > 544			dev_get_stats(nfo_info->standby_dev, &nfo_info->standby_stats);
   545		} else {
   546			rcu_assign_pointer(nfo_info->primary_dev, slave_dev);
   547			dev_get_stats(nfo_info->primary_dev, &nfo_info->primary_stats);
   548			failover_dev->min_mtu = slave_dev->min_mtu;
   549			failover_dev->max_mtu = slave_dev->max_mtu;
   550		}
   551	
   552		net_failover_compute_features(failover_dev);
   553	
   554		call_netdevice_notifiers(NETDEV_JOIN, slave_dev);
   555	
   556		netdev_info(failover_dev, "failover %s slave:%s registered\n",
   557			    slave_is_standby ? "standby" : "primary", slave_dev->name);
   558	
   559		goto done;
   560	
   561	err_upper_link:
   562		netdev_rx_handler_unregister(slave_dev);
   563	err_handler_register:
   564		vlan_vids_del_by_dev(slave_dev, failover_dev);
   565	err_vlan_add:
   566		dev_uc_unsync(slave_dev, failover_dev);
   567		dev_mc_unsync(slave_dev, failover_dev);
   568		dev_close(slave_dev);
   569	err_dev_open:
   570		dev_put(slave_dev);
   571		dev_set_mtu(slave_dev, orig_mtu);
   572	done:
   573		return NOTIFY_DONE;
   574	}
   575	

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

Re: [PATCH net-next v8 2/4] net: Introduce generic failover module

[Dan Carpenter]

Hi Sridhar,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on net-next/master]
url:    https://github.com/0day-ci/linux/commits/Sridhar-Samudrala/Enable-virtio_net-to-act-as-a-standby-for-a-passthru-device/20180427-183842

smatch warnings:
net/core/net_failover.c:229 net_failover_change_mtu() error: we previously assumed 'primary_dev' could be null (see line 219)
net/core/net_failover.c:279 net_failover_vlan_rx_add_vid() error: we previously assumed 'primary_dev' could be null (see line 269)

# https://github.com/0day-ci/linux/commit/5a5f2e3efcb699867db79543dfebe764927b9c93
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 5a5f2e3efcb699867db79543dfebe764927b9c93
vim +/primary_dev +229 net/core/net_failover.c

5a5f2e3e Sridhar Samudrala 2018-04-25  211  
5a5f2e3e Sridhar Samudrala 2018-04-25  212  static int net_failover_change_mtu(struct net_device *dev, int new_mtu)
5a5f2e3e Sridhar Samudrala 2018-04-25  213  {
5a5f2e3e Sridhar Samudrala 2018-04-25  214  	struct net_failover_info *nfo_info = netdev_priv(dev);
5a5f2e3e Sridhar Samudrala 2018-04-25  215  	struct net_device *primary_dev, *standby_dev;
5a5f2e3e Sridhar Samudrala 2018-04-25  216  	int ret = 0;
5a5f2e3e Sridhar Samudrala 2018-04-25  217  
5a5f2e3e Sridhar Samudrala 2018-04-25  218  	primary_dev = rcu_dereference(nfo_info->primary_dev);
5a5f2e3e Sridhar Samudrala 2018-04-25 @219  	if (primary_dev) {
5a5f2e3e Sridhar Samudrala 2018-04-25  220  		ret = dev_set_mtu(primary_dev, new_mtu);
5a5f2e3e Sridhar Samudrala 2018-04-25  221  		if (ret)
5a5f2e3e Sridhar Samudrala 2018-04-25  222  			return ret;
5a5f2e3e Sridhar Samudrala 2018-04-25  223  	}
5a5f2e3e Sridhar Samudrala 2018-04-25  224  
5a5f2e3e Sridhar Samudrala 2018-04-25  225  	standby_dev = rcu_dereference(nfo_info->standby_dev);
5a5f2e3e Sridhar Samudrala 2018-04-25  226  	if (standby_dev) {
5a5f2e3e Sridhar Samudrala 2018-04-25  227  		ret = dev_set_mtu(standby_dev, new_mtu);
5a5f2e3e Sridhar Samudrala 2018-04-25  228  		if (ret) {
5a5f2e3e Sridhar Samudrala 2018-04-25 @229  			dev_set_mtu(primary_dev, dev->mtu);
5a5f2e3e Sridhar Samudrala 2018-04-25  230  			return ret;
5a5f2e3e Sridhar Samudrala 2018-04-25  231  		}
5a5f2e3e Sridhar Samudrala 2018-04-25  232  	}
5a5f2e3e Sridhar Samudrala 2018-04-25  233  
5a5f2e3e Sridhar Samudrala 2018-04-25  234  	dev->mtu = new_mtu;
5a5f2e3e Sridhar Samudrala 2018-04-25  235  
5a5f2e3e Sridhar Samudrala 2018-04-25  236  	return 0;
5a5f2e3e Sridhar Samudrala 2018-04-25  237  }
5a5f2e3e Sridhar Samudrala 2018-04-25  238  
5a5f2e3e Sridhar Samudrala 2018-04-25  239  static void net_failover_set_rx_mode(struct net_device *dev)
5a5f2e3e Sridhar Samudrala 2018-04-25  240  {
5a5f2e3e Sridhar Samudrala 2018-04-25  241  	struct net_failover_info *nfo_info = netdev_priv(dev);
5a5f2e3e Sridhar Samudrala 2018-04-25  242  	struct net_device *slave_dev;
5a5f2e3e Sridhar Samudrala 2018-04-25  243  
5a5f2e3e Sridhar Samudrala 2018-04-25  244  	rcu_read_lock();
5a5f2e3e Sridhar Samudrala 2018-04-25  245  
5a5f2e3e Sridhar Samudrala 2018-04-25  246  	slave_dev = rcu_dereference(nfo_info->primary_dev);
5a5f2e3e Sridhar Samudrala 2018-04-25  247  	if (slave_dev) {
5a5f2e3e Sridhar Samudrala 2018-04-25  248  		dev_uc_sync_multiple(slave_dev, dev);
5a5f2e3e Sridhar Samudrala 2018-04-25  249  		dev_mc_sync_multiple(slave_dev, dev);
5a5f2e3e Sridhar Samudrala 2018-04-25  250  	}
5a5f2e3e Sridhar Samudrala 2018-04-25  251  
5a5f2e3e Sridhar Samudrala 2018-04-25  252  	slave_dev = rcu_dereference(nfo_info->standby_dev);
5a5f2e3e Sridhar Samudrala 2018-04-25  253  	if (slave_dev) {
5a5f2e3e Sridhar Samudrala 2018-04-25  254  		dev_uc_sync_multiple(slave_dev, dev);
5a5f2e3e Sridhar Samudrala 2018-04-25  255  		dev_mc_sync_multiple(slave_dev, dev);
5a5f2e3e Sridhar Samudrala 2018-04-25  256  	}
5a5f2e3e Sridhar Samudrala 2018-04-25  257  
5a5f2e3e Sridhar Samudrala 2018-04-25  258  	rcu_read_unlock();
5a5f2e3e Sridhar Samudrala 2018-04-25  259  }
5a5f2e3e Sridhar Samudrala 2018-04-25  260  
5a5f2e3e Sridhar Samudrala 2018-04-25  261  static int net_failover_vlan_rx_add_vid(struct net_device *dev, __be16 proto,
5a5f2e3e Sridhar Samudrala 2018-04-25  262  					u16 vid)
5a5f2e3e Sridhar Samudrala 2018-04-25  263  {
5a5f2e3e Sridhar Samudrala 2018-04-25  264  	struct net_failover_info *nfo_info = netdev_priv(dev);
5a5f2e3e Sridhar Samudrala 2018-04-25  265  	struct net_device *primary_dev, *standby_dev;
5a5f2e3e Sridhar Samudrala 2018-04-25  266  	int ret = 0;
5a5f2e3e Sridhar Samudrala 2018-04-25  267  
5a5f2e3e Sridhar Samudrala 2018-04-25  268  	primary_dev = rcu_dereference(nfo_info->primary_dev);
5a5f2e3e Sridhar Samudrala 2018-04-25 @269  	if (primary_dev) {
5a5f2e3e Sridhar Samudrala 2018-04-25  270  		ret = vlan_vid_add(primary_dev, proto, vid);
5a5f2e3e Sridhar Samudrala 2018-04-25  271  		if (ret)
5a5f2e3e Sridhar Samudrala 2018-04-25  272  			return ret;
5a5f2e3e Sridhar Samudrala 2018-04-25  273  	}
5a5f2e3e Sridhar Samudrala 2018-04-25  274  
5a5f2e3e Sridhar Samudrala 2018-04-25  275  	standby_dev = rcu_dereference(nfo_info->standby_dev);
5a5f2e3e Sridhar Samudrala 2018-04-25  276  	if (standby_dev) {
5a5f2e3e Sridhar Samudrala 2018-04-25  277  		ret = vlan_vid_add(standby_dev, proto, vid);
5a5f2e3e Sridhar Samudrala 2018-04-25  278  		if (ret)
5a5f2e3e Sridhar Samudrala 2018-04-25 @279  			vlan_vid_del(primary_dev, proto, vid);
5a5f2e3e Sridhar Samudrala 2018-04-25  280  	}
5a5f2e3e Sridhar Samudrala 2018-04-25  281  
5a5f2e3e Sridhar Samudrala 2018-04-25  282  	return ret;
5a5f2e3e Sridhar Samudrala 2018-04-25  283  }
5a5f2e3e Sridhar Samudrala 2018-04-25  284