netdev - Re: [PATCH net-next v2 4/7] devlink: allow subports on devlink PCI ports

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Message-ID: <20190302094116.GQ2314@nanopsycho>
Date:   Sat, 2 Mar 2019 10:41:16 +0100
From:   Jiri Pirko <jiri@...nulli.us>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org,
        oss-drivers@...ronome.com
Subject: Re: [PATCH net-next v2 4/7] devlink: allow subports on devlink PCI
 ports

Fri, Mar 01, 2019 at 07:04:50PM CET, jakub.kicinski@...ronome.com wrote:
>PCI endpoint corresponds to a PCI device, but such device
>can have one more more logical device ports associated with it.
>We need a way to distinguish those. Add a PCI subport in the
>dumps and print the info in phys_port_name appropriately.
>
>This is not equivalent to port splitting, there is no split
>group. It's just a way of representing multiple netdevs on
>a single PCI function.
>
>Note that the quality of being multiport pertains only to
>the PCI function itself. A PF having multiple netdevs does
>not mean that its VFs will also have multiple, or that VFs
>are associated with any particular port of a multiport VF.
>
>Example (bus 05 device has subports, bus 82 has only one port per
>function):
>
>$ devlink port
>pci/0000:05:00.0/0: type eth netdev enp5s0np0 flavour physical
>pci/0000:05:00.0/10000: type eth netdev enp5s0npf0s0 flavour pci_pf pf 0 subport 0
>pci/0000:05:00.0/4: type eth netdev enp5s0np1 flavour physical
>pci/0000:05:00.0/11000: type eth netdev enp5s0npf0s1 flavour pci_pf pf 0 subport 1

So these subport devlink ports are eswitch ports for subports, right?

Please see the following drawing:

                                 +---+      +---+      +---+
                            pfsub| 5 |    vf| 6 |      | 7 |pfsub
                                 +-+-+      +-+-+      +-+-+
physical link <---------+          |          |          |
                        |          |          |          |
                        |          |          |          |
                        |          |          |          |
                      +-+-+      +-+-+      +-+-+      +-+-+
                      | 1 |      | 2 |      | 3 |      | 4 |
                   +--+---+------+---+------+---+------+---+--+
                   |  physical    pfsub      vf         pfsub |
                   |  port        port       port       port  |
                   |                                          |
                   |                  eswitch                 |
                   |                                          |
                   |                                          |
                   +------------------------------------------+

1) pci/0000:05:00.0/0: type eth netdev enp5s0np0 flavour physical switch_id 00154d130d2f
2) pci/0000:05:00.0/10000: type eth netdev enp5s0npf0s0 flavour pci_pf pf 0 subport 0 switch_id 00154d130d2f
3) pci/0000:05:00.0/10001: type eth netdev enp5s0npf0vf0 flavour pci_vf pf 0 vf 0 switch_id 00154d130d2f
4) pci/0000:05:00.0/10001: type eth netdev enp5s0npf0s1 flavour pci_pf pf 0 subport 1 switch_id 00154d130d2f

This is basically what you have and I think we are in sync with that.
But what about 5,6,7? Should they have devlink port instances too?

5) pci/0000:05:00.0/1: type eth netdev enp5s0f0?? flavour ???? pf 0 subport 0
6) pci/0000:05:10.1/0: type eth netdev enp5s10f0 flavour ???? pf 0 vf 0
7) pci/0000:05:00.0/1: type eth netdev enp5s0f0?? flavour ???? pf 0 subport 1

These are the "peers".
I think that there could be flavours "pci_pf" and "pci_vf". Then the
"representors" (switch ports) could have flavours "pci_pf_port" and
"pci_vf_port" or something like that. User can see right away
that is not "PF" of "VF" but rather something "on the other end".
Note there is no "switch_id" for these devlink ports that tells the user
these devlink ports are not part of any switch.
What do you think?


>pci/0000:82:00.0/0: type eth netdev p4p1 flavour physical
>pci/0000:82:00.0/10000: type eth netdev eth0 flavour pci_pf pf 0
>

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