The failover module provides a generic interface for paravirtual drivers
to register a netdev and a set of ops with a failover instance. The ops
are used as event handlers that get called to handle netdev register/
unregister/link change/name change events on slave pci ethernet devices
with the same mac address as the failover netdev.
This enables paravirtual drivers to use a VF as an accelerated low latency
datapath. It also allows migration of VMs with direct attached VFs by
failing over to the paravirtual datapath when the VF is unplugged.
Signed-off-by: Sridhar Samudrala <sridhar.samudrala@xxxxxxxxx>
---
Documentation/networking/failover.rst | 18 ++
MAINTAINERS | 8 +
include/linux/netdevice.h | 16 ++
include/net/failover.h | 36 ++++
net/Kconfig | 13 ++
net/core/Makefile | 1 +
net/core/failover.c | 315 ++++++++++++++++++++++++++++++++++
7 files changed, 407 insertions(+)
create mode 100644 Documentation/networking/failover.rst
create mode 100644 include/net/failover.h
create mode 100644 net/core/failover.c
diff --git a/Documentation/networking/failover.rst b/Documentation/networking/failover.rst
new file mode 100644
index 000000000000..f0c8483cdbf5
--- /dev/null
+++ b/Documentation/networking/failover.rst
@@ -0,0 +1,18 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+========
+FAILOVER
+========
+
+Overview
+========
+
+The failover module provides a generic interface for paravirtual drivers
+to register a netdev and a set of ops with a failover instance. The ops
+are used as event handlers that get called to handle netdev register/
+unregister/link change/name change events on slave pci ethernet devices
+with the same mac address as the failover netdev.
+
+This enables paravirtual drivers to use a VF as an accelerated low latency
+datapath. It also allows live migration of VMs with direct attached VFs by
+failing over to the paravirtual datapath when the VF is unplugged.
diff --git a/MAINTAINERS b/MAINTAINERS
index 032807a95558..ee0ce10b2a8d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5412,6 +5412,14 @@ S: Maintained
F: Documentation/hwmon/f71805f
F: drivers/hwmon/f71805f.c
+FAILOVER MODULE
+M: Sridhar Samudrala <sridhar.samudrala@xxxxxxxxx>
+L: netdev@xxxxxxxxxxxxxxx
+S: Supported
+F: net/core/failover.c
+F: include/net/failover.h
+F: Documentation/networking/failover.rst
+
FANOTIFY
M: Jan Kara <jack@xxxxxxx>
R: Amir Goldstein <amir73il@xxxxxxxxx>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 03ed492c4e14..0f4ba52b641d 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1421,6 +1421,8 @@ 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,
@@ -1450,6 +1452,8 @@ 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
@@ -1478,6 +1482,8 @@ 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.
@@ -4321,6 +4327,16 @@ 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/failover.h b/include/net/failover.h
new file mode 100644
index 000000000000..bb15438f39c7
--- /dev/null
+++ b/include/net/failover.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2018, Intel Corporation. */
+
+#ifndef _FAILOVER_H
+#define _FAILOVER_H
+
+#include <linux/netdevice.h>
+
+struct failover_ops {
+ int (*slave_pre_register)(struct net_device *slave_dev,
+ struct net_device *failover_dev);
+ int (*slave_register)(struct net_device *slave_dev,
+ struct net_device *failover_dev);
+ int (*slave_pre_unregister)(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);
+ int (*slave_name_change)(struct net_device *slave_dev,
+ struct net_device *failover_dev);
+ rx_handler_result_t (*slave_handle_frame)(struct sk_buff **pskb);
+};
+
+struct failover {
+ struct list_head list;
+ struct net_device __rcu *failover_dev;
+ struct failover_ops __rcu *ops;
+};
+
+struct failover *failover_register(struct net_device *dev,
+ struct failover_ops *ops);
+void failover_unregister(struct failover *failover);
+int failover_slave_unregister(struct net_device *slave_dev);
+
+#endif /* _FAILOVER_H */
diff --git a/net/Kconfig b/net/Kconfig
index df8d45ef47d8..d581c4f0f1c4 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -430,6 +430,19 @@ config MAY_USE_DEVLINK
config PAGE_POOL
bool
+config FAILOVER
+ tristate "Generic failover module"
+ help
+ The failover module provides a generic interface for paravirtual
+ drivers to register a netdev and a set of ops with a failover
+ instance. The ops are used as event handlers that get called to
+ handle netdev register/unregister/link change/name change events
+ on slave pci ethernet devices with the same mac address as the
+ failover netdev. This enables paravirtual drivers to use a
+ VF as an accelerated low latency datapath. It also allows live
+ migration of VMs with direct attached VFs by failing over to the
+ paravirtual datapath when the VF is unplugged.
+
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..80175e6a2eb8 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_FAILOVER) += failover.o
diff --git a/net/core/failover.c b/net/core/failover.c
new file mode 100644
index 000000000000..4a92a98ccce9
--- /dev/null
+++ b/net/core/failover.c
@@ -0,0 +1,315 @@
+// 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.
+ */
+
+#include <linux/module.h>
+#include <linux/etherdevice.h>
+#include <uapi/linux/if_arp.h>
+#include <linux/rtnetlink.h>
+#include <linux/if_vlan.h>
+#include <net/failover.h>
+
+static LIST_HEAD(failover_list);
+static DEFINE_SPINLOCK(failover_lock);
+
+static struct net_device *failover_get_bymac(u8 *mac, struct failover_ops **ops)
+{
+ struct net_device *failover_dev;
+ struct failover *failover;
+
+ spin_lock(&failover_lock);
+ list_for_each_entry(failover, &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(&failover_lock);
+ return failover_dev;
+ }
+ }
+ spin_unlock(&failover_lock);
+ return NULL;
+}
+
+/**
+ * failover_slave_register - Register a slave netdev
+ *
+ * @slave_dev: slave netdev that is being registered
+ *
+ * Registers a slave device to a failover instance. Only ethernet devices
+ * are supported.
+ */
+static int failover_slave_register(struct net_device *slave_dev)
+{
+ struct netdev_lag_upper_info lag_upper_info;
+ struct net_device *failover_dev;
+ struct failover_ops *fops;
+ int err;
+
+ if (slave_dev->type != ARPHRD_ETHER)
+ goto done;
+
+ ASSERT_RTNL();
+
+ failover_dev = failover_get_bymac(slave_dev->perm_addr, &fops);
+ if (!failover_dev)
+ goto done;
+
+ if (fops && fops->slave_pre_register &&
+ fops->slave_pre_register(slave_dev, failover_dev))
+ goto done;
+
+ err = netdev_rx_handler_register(slave_dev, fops->slave_handle_frame,
+ failover_dev);
+ if (err) {
+ netdev_err(slave_dev, "can not register failover rx handler (err = %d)\n",
+ err);
+ goto done;
+ }
+
+ lag_upper_info.tx_type = NETDEV_LAG_TX_TYPE_ACTIVEBACKUP;
+ err = netdev_master_upper_dev_link(slave_dev, failover_dev, NULL,
+ &lag_upper_info, 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 (fops && fops->slave_register &&
+ !fops->slave_register(slave_dev, failover_dev))
+ return NOTIFY_OK;
+
+ netdev_upper_dev_unlink(slave_dev, failover_dev);
+ slave_dev->priv_flags &= ~IFF_FAILOVER_SLAVE;
+err_upper_link:
+ netdev_rx_handler_unregister(slave_dev);
+done:
+ return NOTIFY_DONE;
+}
+
+/**
+ * failover_slave_unregister - Unregister a slave netdev
+ *
+ * @slave_dev: slave netdev that is being unregistered
+ *
+ * Unregisters a slave device from a failover instance.
+ */
+int failover_slave_unregister(struct net_device *slave_dev)
+{
+ struct net_device *failover_dev;
+ struct failover_ops *fops;
+
+ if (!netif_is_failover_slave(slave_dev))
+ goto done;
+
+ ASSERT_RTNL();
+
+ failover_dev = failover_get_bymac(slave_dev->perm_addr, &fops);
+ if (!failover_dev)
+ goto done;
+
+ if (fops && fops->slave_pre_unregister &&
+ fops->slave_pre_unregister(slave_dev, failover_dev))
+ goto done;
+
+ netdev_rx_handler_unregister(slave_dev);
+ netdev_upper_dev_unlink(slave_dev, failover_dev);
+ slave_dev->priv_flags &= ~IFF_FAILOVER_SLAVE;
+
+ if (fops && fops->slave_unregister &&
+ !fops->slave_unregister(slave_dev, failover_dev))
+ return NOTIFY_OK;
+
+done:
+ return NOTIFY_DONE;
+}
+EXPORT_SYMBOL_GPL(failover_slave_unregister);
+
+static int failover_slave_link_change(struct net_device *slave_dev)
+{
+ struct net_device *failover_dev;
+ struct failover_ops *fops;
+
+ if (!netif_is_failover_slave(slave_dev))
+ goto done;
+
+ ASSERT_RTNL();
+
+ failover_dev = failover_get_bymac(slave_dev->perm_addr, &fops);
+ if (!failover_dev)
+ goto done;
+
+ if (!netif_running(failover_dev))
+ goto done;
+
+ if (fops && fops->slave_link_change &&
+ !fops->slave_link_change(slave_dev, failover_dev))
+ return NOTIFY_OK;
+
+done:
+ return NOTIFY_DONE;
+}
+
+static int failover_slave_name_change(struct net_device *slave_dev)
+{
+ struct net_device *failover_dev;
+ struct failover_ops *fops;
+
+ if (!netif_is_failover_slave(slave_dev))
+ goto done;
+
+ ASSERT_RTNL();
+
+ failover_dev = failover_get_bymac(slave_dev->perm_addr, &fops);
+ if (!failover_dev)
+ goto done;
+
+ if (!netif_running(failover_dev))
+ goto done;
+
+ if (fops && fops->slave_name_change &&
+ !fops->slave_name_change(slave_dev, failover_dev))
+ return NOTIFY_OK;
+
+done:
+ return NOTIFY_DONE;
+}
+
+static int
+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 failover_slave_register(event_dev);
+ case NETDEV_UNREGISTER:
+ return failover_slave_unregister(event_dev);
+ case NETDEV_UP:
+ case NETDEV_DOWN:
+ case NETDEV_CHANGE:
+ return failover_slave_link_change(event_dev);
+ case NETDEV_CHANGENAME:
+ return failover_slave_name_change(event_dev);
+ default:
+ return NOTIFY_DONE;
+ }
+}
+
+static struct notifier_block failover_notifier = {
+ .notifier_call = failover_event,
+};
+
+static void
+failover_existing_slave_register(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))
+ failover_slave_register(dev);
+ }
+ rtnl_unlock();
+}
+
+/**
+ * failover_register - Register a failover instance
+ *
+ * @dev: failover netdev
+ * @ops: failover ops
+ *
+ * Allocate and register a failover instance for a failover netdev. ops
+ * provides handlers for slave device register/unregister/link change/
+ * name change events.
+ *
+ * Return: pointer to failover instance
+ */
+struct failover *failover_register(struct net_device *dev,
+ struct failover_ops *ops)
+{
+ struct failover *failover;
+
+ if (dev->type != ARPHRD_ETHER)
+ return ERR_PTR(-EINVAL);
+
+ failover = kzalloc(sizeof(*failover), GFP_KERNEL);
+ if (!failover)
+ return ERR_PTR(-ENOMEM);
+
+ rcu_assign_pointer(failover->ops, ops);
+ dev_hold(dev);
+ dev->priv_flags |= IFF_FAILOVER;
+ rcu_assign_pointer(failover->failover_dev, dev);
+
+ spin_lock(&failover_lock);
+ list_add_tail(&failover->list, &failover_list);
+ spin_unlock(&failover_lock);
+
+ netdev_info(dev, "failover master:%s registered\n", dev->name);
+
+ failover_existing_slave_register(dev);
+
+ return failover;
+}
+EXPORT_SYMBOL_GPL(failover_register);
+
+/**
+ * failover_unregister - Unregister a failover instance
+ *
+ * @failover: pointer to failover instance
+ *
+ * Unregisters and frees a failover instance.
+ */
+void failover_unregister(struct 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(&failover_lock);
+ list_del(&failover->list);
+ spin_unlock(&failover_lock);
+
+ kfree(failover);
+}
+EXPORT_SYMBOL_GPL(failover_unregister);
+
+static __init int
+failover_init(void)
+{
+ register_netdevice_notifier(&failover_notifier);
+
+ return 0;
+}
+module_init(failover_init);
+
+static __exit
+void failover_exit(void)
+{
+ unregister_netdevice_notifier(&failover_notifier);
+}
+module_exit(failover_exit);
+
+MODULE_DESCRIPTION("Generic failover infrastructure/interface");
+MODULE_LICENSE("GPL v2");
--
2.14.3
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