netdev - [patch net-next RFCv2 00/10] introduce line card support for modular switch

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Date:   Fri, 22 Jan 2021 10:46:38 +0100
From:   Jiri Pirko <jiri@...nulli.us>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, kuba@...nel.org, jacob.e.keller@...el.com,
        roopa@...dia.com, andrew@...n.ch, dsahern@...il.com,
        mlxsw@...dia.com
Subject: [patch net-next RFCv2 00/10] introduce line card support for modular switch

From: Jiri Pirko <jiri@...dia.com>

This patchset introduces support for modular switch systems.
NVIDIA Mellanox SN4800 is an example of such. It contains 8 slots
to accomodate line cards - basically replaceable PHY modules.
Available line cards include:
16X 100GbE (QSFP28)
8X 200GbE (QSFP56)
4X 400GbE (QSFP-DD)

Similar to split cabels, it is essencial for the correctness of
configuration and funcionality to treat the line card entities
in the same way, no matter the line card is inserted or not.
Meaning, the netdevice of a line card port cannot just disappear
when line card is removed. Also, system admin needs to be able
to apply configuration on netdevices belonging to line card port
even before the linecard gets inserted. The nature of a line card
is not "a pluggable device", but "a pluggable PHY module". 

To resolve this, a concept of "provisioning" is introduced.
The user may "provision" certain slot with a line card type.
Driver then creates all instances (devlink ports, netdevices, etc)
related to this line card type. The carrier of netdevices stays down.
Once the line card is inserted and activated, the carrier of the
related netdevices goes up.

Once user does not want to use the line card related instances
anymore, he can "unprovision" the slot. Driver then removes the
instances.

Patches 1-5 are extending devlink driver API and UAPI in order to
register, show, dump, provision and activate the line card.
Patches 6-9 are implementing the introduced API in netdevsim

Example:

# Create a new netdevsim device, with no ports and 2 line cards:
$ echo "10 0 2" >/sys/bus/netdevsim/new_device
$ devlink port # No ports are listed
$ devlink lc
netdevsim/netdevsim10:
  lc 0 state unprovisioned
    supported_types:
       card1port card2ports card4ports
  lc 1 state unprovisioned
    supported_types:
       card1port card2ports card4ports

# Note that driver advertizes supported line card types. In case of
# netdevsim, these are 3.

$ devlink lc set netdevsim/netdevsim10 lc 0 type card4ports
$ devlink lc
netdevsim/netdevsim10:
  lc 0 state provisioned type card4ports
    supported_types:
       card1port card2ports card4ports
  lc 1 state unprovisioned
    supported_types:
       card1port card2ports card4ports
$ devlink port
netdevsim/netdevsim10/1000: type eth netdev eni10nl0p1 flavour physical lc 0 port 1 splittable false
netdevsim/netdevsim10/1001: type eth netdev eni10nl0p2 flavour physical lc 0 port 2 splittable false
netdevsim/netdevsim10/1002: type eth netdev eni10nl0p3 flavour physical lc 0 port 3 splittable false
netdevsim/netdevsim10/1003: type eth netdev eni10nl0p4 flavour physical lc 0 port 4 splittable false
#                                                 ^^                    ^^^^
#                                     netdev name adjusted          index of a line card this port belongs to

$ ip link set eni10nl0p1 up
$ ip link show eni10nl0p1
165: eni10nl0p1: <NO-CARRIER,BROADCAST,NOARP,UP> mtu 1500 qdisc noqueue state DOWN mode DEFAULT group default qlen 1000
    link/ether 7e:2d:05:93:d3:d1 brd ff:ff:ff:ff:ff:ff

# Now insert the line card using debugfs. That emulates plug-in even
# on real hardware:
$ echo "card4ports"> /sys/kernel/debug/netdevsim/netdevsim10/linecards/0/inserted_type
$ ip link show eni10nl0p1
165: eni10nl0p1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
    link/ether 7e:2d:05:93:d3:d1 brd ff:ff:ff:ff:ff:ff
# The carrier is UP now.

Jiri Pirko (10):
  devlink: add support to create line card and expose to user
  devlink: implement line card provisioning
  devlink: implement line card active state
  devlink: append split port number to the port name
  devlink: add port to line card relationship set
  netdevsim: introduce line card support
  netdevsim: allow port objects to be linked with line cards
  netdevsim: create devlink line card object and implement provisioning
  netdevsim: implement line card activation
  selftests: add netdevsim devlink lc test

 drivers/net/netdevsim/bus.c                   |  21 +-
 drivers/net/netdevsim/dev.c                   | 425 +++++++++++++++-
 drivers/net/netdevsim/netdev.c                |   2 +
 drivers/net/netdevsim/netdevsim.h             |  26 +
 include/net/devlink.h                         |  44 ++
 include/uapi/linux/devlink.h                  |  23 +
 net/core/devlink.c                            | 463 +++++++++++++++++-
 .../drivers/net/netdevsim/devlink.sh          |  62 ++-
 8 files changed, 1040 insertions(+), 26 deletions(-)

-- 
2.26.2