docs: networking: convert switchdev.txt to ReST

- add SPDX header;
- use copyright symbol;
- adjust title markup;
- mark code blocks and literals as such;
- mark tables as such;
- adjust identation, whitespaces and blank lines where needed;
- add to networking/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 0 insertions, 373 deletions

diff --git a/Documentation/networking/switchdev.txt b/Documentation/networking/switchdev.txt
deleted file mode 100644
index 86174ce8cd13..000000000000
--- a/Documentation/networking/switchdev.txt
+++ /dev/null
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-Ethernet switch device driver model (switchdev)
-===============================================
-Copyright (c) 2014 Jiri Pirko <jiri@resnulli.us>
-Copyright (c) 2014-2015 Scott Feldman <sfeldma@gmail.com>
-
-
-The Ethernet switch device driver model (switchdev) is an in-kernel driver
-model for switch devices which offload the forwarding (data) plane from the
-kernel.
-
-Figure 1 is a block diagram showing the components of the switchdev model for
-an example setup using a data-center-class switch ASIC chip.  Other setups
-with SR-IOV or soft switches, such as OVS, are possible.
-
-
-                             User-space tools
-
-       user space                   |
-      +-------------------------------------------------------------------+
-       kernel                       | Netlink
-                                    |
-                     +--------------+-------------------------------+
-                     |         Network stack                        |
-                     |           (Linux)                            |
-                     |                                              |
-                     +----------------------------------------------+
-
-                           sw1p2     sw1p4     sw1p6
-                      sw1p1  +  sw1p3  +  sw1p5  +          eth1
-                        +    |    +    |    +    |            +
-                        |    |    |    |    |    |            |
-                     +--+----+----+----+----+----+---+  +-----+-----+
-                     |         Switch driver         |  |    mgmt   |
-                     |        (this document)        |  |   driver  |
-                     |                               |  |           |
-                     +--------------+----------------+  +-----------+
-                                    |
-       kernel                       | HW bus (eg PCI)
-      +-------------------------------------------------------------------+
-       hardware                     |
-                     +--------------+----------------+
-                     |         Switch device (sw1)   |
-                     |  +----+                       +--------+
-                     |  |    v offloaded data path   | mgmt port
-                     |  |    |                       |
-                     +--|----|----+----+----+----+---+
-                        |    |    |    |    |    |
-                        +    +    +    +    +    +
-                       p1   p2   p3   p4   p5   p6
-
-                             front-panel ports
-
-
-                                    Fig 1.
-
-
-Include Files
--------------
-
-#include <linux/netdevice.h>
-#include <net/switchdev.h>
-
-
-Configuration
--------------
-
-Use "depends NET_SWITCHDEV" in driver's Kconfig to ensure switchdev model
-support is built for driver.
-
-
-Switch Ports
-------------
-
-On switchdev driver initialization, the driver will allocate and register a
-struct net_device (using register_netdev()) for each enumerated physical switch
-port, called the port netdev.  A port netdev is the software representation of
-the physical port and provides a conduit for control traffic to/from the
-controller (the kernel) and the network, as well as an anchor point for higher
-level constructs such as bridges, bonds, VLANs, tunnels, and L3 routers.  Using
-standard netdev tools (iproute2, ethtool, etc), the port netdev can also
-provide to the user access to the physical properties of the switch port such
-as PHY link state and I/O statistics.
-
-There is (currently) no higher-level kernel object for the switch beyond the
-port netdevs.  All of the switchdev driver ops are netdev ops or switchdev ops.
-
-A switch management port is outside the scope of the switchdev driver model.
-Typically, the management port is not participating in offloaded data plane and
-is loaded with a different driver, such as a NIC driver, on the management port
-device.
-
-Switch ID
-^^^^^^^^^
-
-The switchdev driver must implement the net_device operation
-ndo_get_port_parent_id for each port netdev, returning the same physical ID for
-each port of a switch. The ID must be unique between switches on the same
-system. The ID does not need to be unique between switches on different
-systems.
-
-The switch ID is used to locate ports on a switch and to know if aggregated
-ports belong to the same switch.
-
-Port Netdev Naming
-^^^^^^^^^^^^^^^^^^
-
-Udev rules should be used for port netdev naming, using some unique attribute
-of the port as a key, for example the port MAC address or the port PHYS name.
-Hard-coding of kernel netdev names within the driver is discouraged; let the
-kernel pick the default netdev name, and let udev set the final name based on a
-port attribute.
-
-Using port PHYS name (ndo_get_phys_port_name) for the key is particularly
-useful for dynamically-named ports where the device names its ports based on
-external configuration.  For example, if a physical 40G port is split logically
-into 4 10G ports, resulting in 4 port netdevs, the device can give a unique
-name for each port using port PHYS name.  The udev rule would be:
-
-SUBSYSTEM=="net", ACTION=="add", ATTR{phys_switch_id}=="<phys_switch_id>", \
-	ATTR{phys_port_name}!="", NAME="swX$attr{phys_port_name}"
-
-Suggested naming convention is "swXpYsZ", where X is the switch name or ID, Y
-is the port name or ID, and Z is the sub-port name or ID.  For example, sw1p1s0
-would be sub-port 0 on port 1 on switch 1.
-
-Port Features
-^^^^^^^^^^^^^
-
-NETIF_F_NETNS_LOCAL
-
-If the switchdev driver (and device) only supports offloading of the default
-network namespace (netns), the driver should set this feature flag to prevent
-the port netdev from being moved out of the default netns.  A netns-aware
-driver/device would not set this flag and be responsible for partitioning
-hardware to preserve netns containment.  This means hardware cannot forward
-traffic from a port in one namespace to another port in another namespace.
-
-Port Topology
-^^^^^^^^^^^^^
-
-The port netdevs representing the physical switch ports can be organized into
-higher-level switching constructs.  The default construct is a standalone
-router port, used to offload L3 forwarding.  Two or more ports can be bonded
-together to form a LAG.  Two or more ports (or LAGs) can be bridged to bridge
-L2 networks.  VLANs can be applied to sub-divide L2 networks.  L2-over-L3
-tunnels can be built on ports.  These constructs are built using standard Linux
-tools such as the bridge driver, the bonding/team drivers, and netlink-based
-tools such as iproute2.
-
-The switchdev driver can know a particular port's position in the topology by
-monitoring NETDEV_CHANGEUPPER notifications.  For example, a port moved into a
-bond will see it's upper master change.  If that bond is moved into a bridge,
-the bond's upper master will change.  And so on.  The driver will track such
-movements to know what position a port is in in the overall topology by
-registering for netdevice events and acting on NETDEV_CHANGEUPPER.
-
-L2 Forwarding Offload
----------------------
-
-The idea is to offload the L2 data forwarding (switching) path from the kernel
-to the switchdev device by mirroring bridge FDB entries down to the device.  An
-FDB entry is the {port, MAC, VLAN} tuple forwarding destination.
-
-To offloading L2 bridging, the switchdev driver/device should support:
-
-	- Static FDB entries installed on a bridge port
-	- Notification of learned/forgotten src mac/vlans from device
-	- STP state changes on the port
-	- VLAN flooding of multicast/broadcast and unknown unicast packets
-
-Static FDB Entries
-^^^^^^^^^^^^^^^^^^
-
-The switchdev driver should implement ndo_fdb_add, ndo_fdb_del and ndo_fdb_dump
-to support static FDB entries installed to the device.  Static bridge FDB
-entries are installed, for example, using iproute2 bridge cmd:
-
-	bridge fdb add ADDR dev DEV [vlan VID] [self]
-
-The driver should use the helper switchdev_port_fdb_xxx ops for ndo_fdb_xxx
-ops, and handle add/delete/dump of SWITCHDEV_OBJ_ID_PORT_FDB object using
-switchdev_port_obj_xxx ops.
-
-XXX: what should be done if offloading this rule to hardware fails (for
-example, due to full capacity in hardware tables) ?
-
-Note: by default, the bridge does not filter on VLAN and only bridges untagged
-traffic.  To enable VLAN support, turn on VLAN filtering:
-
-	echo 1 >/sys/class/net/<bridge>/bridge/vlan_filtering
-
-Notification of Learned/Forgotten Source MAC/VLANs
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-The switch device will learn/forget source MAC address/VLAN on ingress packets
-and notify the switch driver of the mac/vlan/port tuples.  The switch driver,
-in turn, will notify the bridge driver using the switchdev notifier call:
-
-	err = call_switchdev_notifiers(val, dev, info, extack);
-
-Where val is SWITCHDEV_FDB_ADD when learning and SWITCHDEV_FDB_DEL when
-forgetting, and info points to a struct switchdev_notifier_fdb_info.  On
-SWITCHDEV_FDB_ADD, the bridge driver will install the FDB entry into the
-bridge's FDB and mark the entry as NTF_EXT_LEARNED.  The iproute2 bridge
-command will label these entries "offload":
-
-	$ bridge fdb
-	52:54:00:12:35:01 dev sw1p1 master br0 permanent
-	00:02:00:00:02:00 dev sw1p1 master br0 offload
-	00:02:00:00:02:00 dev sw1p1 self
-	52:54:00:12:35:02 dev sw1p2 master br0 permanent
-	00:02:00:00:03:00 dev sw1p2 master br0 offload
-	00:02:00:00:03:00 dev sw1p2 self
-	33:33:00:00:00:01 dev eth0 self permanent
-	01:00:5e:00:00:01 dev eth0 self permanent
-	33:33:ff:00:00:00 dev eth0 self permanent
-	01:80:c2:00:00:0e dev eth0 self permanent
-	33:33:00:00:00:01 dev br0 self permanent
-	01:00:5e:00:00:01 dev br0 self permanent
-	33:33:ff:12:35:01 dev br0 self permanent
-
-Learning on the port should be disabled on the bridge using the bridge command:
-
-	bridge link set dev DEV learning off
-
-Learning on the device port should be enabled, as well as learning_sync:
-
-	bridge link set dev DEV learning on self
-	bridge link set dev DEV learning_sync on self
-
-Learning_sync attribute enables syncing of the learned/forgotten FDB entry to
-the bridge's FDB.  It's possible, but not optimal, to enable learning on the
-device port and on the bridge port, and disable learning_sync.
-
-To support learning, the driver implements switchdev op
-switchdev_port_attr_set for SWITCHDEV_ATTR_PORT_ID_{PRE}_BRIDGE_FLAGS.
-
-FDB Ageing
-^^^^^^^^^^
-
-The bridge will skip ageing FDB entries marked with NTF_EXT_LEARNED and it is
-the responsibility of the port driver/device to age out these entries.  If the
-port device supports ageing, when the FDB entry expires, it will notify the
-driver which in turn will notify the bridge with SWITCHDEV_FDB_DEL.  If the
-device does not support ageing, the driver can simulate ageing using a
-garbage collection timer to monitor FDB entries.  Expired entries will be
-notified to the bridge using SWITCHDEV_FDB_DEL.  See rocker driver for
-example of driver running ageing timer.
-
-To keep an NTF_EXT_LEARNED entry "alive", the driver should refresh the FDB
-entry by calling call_switchdev_notifiers(SWITCHDEV_FDB_ADD, ...).  The
-notification will reset the FDB entry's last-used time to now.  The driver
-should rate limit refresh notifications, for example, no more than once a
-second.  (The last-used time is visible using the bridge -s fdb option).
-
-STP State Change on Port
-^^^^^^^^^^^^^^^^^^^^^^^^
-
-Internally or with a third-party STP protocol implementation (e.g. mstpd), the
-bridge driver maintains the STP state for ports, and will notify the switch
-driver of STP state change on a port using the switchdev op
-switchdev_attr_port_set for SWITCHDEV_ATTR_PORT_ID_STP_UPDATE.
-
-State is one of BR_STATE_*.  The switch driver can use STP state updates to
-update ingress packet filter list for the port.  For example, if port is
-DISABLED, no packets should pass, but if port moves to BLOCKED, then STP BPDUs
-and other IEEE 01:80:c2:xx:xx:xx link-local multicast packets can pass.
-
-Note that STP BDPUs are untagged and STP state applies to all VLANs on the port
-so packet filters should be applied consistently across untagged and tagged
-VLANs on the port.
-
-Flooding L2 domain
-^^^^^^^^^^^^^^^^^^
-
-For a given L2 VLAN domain, the switch device should flood multicast/broadcast
-and unknown unicast packets to all ports in domain, if allowed by port's
-current STP state.  The switch driver, knowing which ports are within which
-vlan L2 domain, can program the switch device for flooding.  The packet may
-be sent to the port netdev for processing by the bridge driver.  The
-bridge should not reflood the packet to the same ports the device flooded,
-otherwise there will be duplicate packets on the wire.
-
-To avoid duplicate packets, the switch driver should mark a packet as already
-forwarded by setting the skb->offload_fwd_mark bit. The bridge driver will mark
-the skb using the ingress bridge port's mark and prevent it from being forwarded
-through any bridge port with the same mark.
-
-It is possible for the switch device to not handle flooding and push the
-packets up to the bridge driver for flooding.  This is not ideal as the number
-of ports scale in the L2 domain as the device is much more efficient at
-flooding packets that software.
-
-If supported by the device, flood control can be offloaded to it, preventing
-certain netdevs from flooding unicast traffic for which there is no FDB entry.
-
-IGMP Snooping
-^^^^^^^^^^^^^
-
-In order to support IGMP snooping, the port netdevs should trap to the bridge
-driver all IGMP join and leave messages.
-The bridge multicast module will notify port netdevs on every multicast group
-changed whether it is static configured or dynamically joined/leave.
-The hardware implementation should be forwarding all registered multicast
-traffic groups only to the configured ports.
-
-L3 Routing Offload
-------------------
-
-Offloading L3 routing requires that device be programmed with FIB entries from
-the kernel, with the device doing the FIB lookup and forwarding.  The device
-does a longest prefix match (LPM) on FIB entries matching route prefix and
-forwards the packet to the matching FIB entry's nexthop(s) egress ports.
-
-To program the device, the driver has to register a FIB notifier handler
-using register_fib_notifier. The following events are available:
-FIB_EVENT_ENTRY_ADD: used for both adding a new FIB entry to the device,
-                     or modifying an existing entry on the device.
-FIB_EVENT_ENTRY_DEL: used for removing a FIB entry
-FIB_EVENT_RULE_ADD, FIB_EVENT_RULE_DEL: used to propagate FIB rule changes
-
-FIB_EVENT_ENTRY_ADD and FIB_EVENT_ENTRY_DEL events pass:
-
-	struct fib_entry_notifier_info {
-		struct fib_notifier_info info; /* must be first */
-		u32 dst;
-		int dst_len;
-		struct fib_info *fi;
-		u8 tos;
-		u8 type;
-		u32 tb_id;
-		u32 nlflags;
-	};
-
-to add/modify/delete IPv4 dst/dest_len prefix on table tb_id.  The *fi
-structure holds details on the route and route's nexthops.  *dev is one of the
-port netdevs mentioned in the route's next hop list.
-
-Routes offloaded to the device are labeled with "offload" in the ip route
-listing:
-
-	$ ip route show
-	default via 192.168.0.2 dev eth0
-	11.0.0.0/30 dev sw1p1  proto kernel  scope link  src 11.0.0.2 offload
-	11.0.0.4/30 via 11.0.0.1 dev sw1p1  proto zebra  metric 20 offload
-	11.0.0.8/30 dev sw1p2  proto kernel  scope link  src 11.0.0.10 offload
-	11.0.0.12/30 via 11.0.0.9 dev sw1p2  proto zebra  metric 20 offload
-	12.0.0.2  proto zebra  metric 30 offload
-		nexthop via 11.0.0.1  dev sw1p1 weight 1
-		nexthop via 11.0.0.9  dev sw1p2 weight 1
-	12.0.0.3 via 11.0.0.1 dev sw1p1  proto zebra  metric 20 offload
-	12.0.0.4 via 11.0.0.9 dev sw1p2  proto zebra  metric 20 offload
-	192.168.0.0/24 dev eth0  proto kernel  scope link  src 192.168.0.15
-
-The "offload" flag is set in case at least one device offloads the FIB entry.
-
-XXX: add/mod/del IPv6 FIB API
-
-Nexthop Resolution
-^^^^^^^^^^^^^^^^^^
-
-The FIB entry's nexthop list contains the nexthop tuple (gateway, dev), but for
-the switch device to forward the packet with the correct dst mac address, the
-nexthop gateways must be resolved to the neighbor's mac address.  Neighbor mac
-address discovery comes via the ARP (or ND) process and is available via the
-arp_tbl neighbor table.  To resolve the routes nexthop gateways, the driver
-should trigger the kernel's neighbor resolution process.  See the rocker
-driver's rocker_port_ipv4_resolve() for an example.
-
-The driver can monitor for updates to arp_tbl using the netevent notifier
-NETEVENT_NEIGH_UPDATE.  The device can be programmed with resolved nexthops
-for the routes as arp_tbl updates.  The driver implements ndo_neigh_destroy
-to know when arp_tbl neighbor entries are purged from the port.