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

Parav Pandit
2019-03-21T15:04:06Z

Hi Jiri,

> -----Original Message-----
> From: Jiri Pirko <jiri@resnulli.us>
> Sent: Thursday, March 21, 2019 4:08 AM
> To: Jakub Kicinski <jakub.kicinski@netronome.com>
> Cc: Parav Pandit <parav@mellanox.com>; Samudrala, Sridhar
> <sridhar.samudrala@intel.com>; davem@davemloft.net;
> netdev@vger.kernel.org; oss-drivers@netronome.com
> Subject: Re: [PATCH net-next v2 4/7] devlink: allow subports on devlink PCI
> ports
>
> Wed, Mar 20, 2019 at 09:22:57PM CET, jakub.kicinski@netronome.com
> wrote:
> >On Wed, 20 Mar 2019 18:24:15 +0000, Parav Pandit wrote:
> >> Hi Jiri, Jakub, Samudrala Sridhar,
> >> > > > > > And physical port in include/uapi/linux/devlink.h also
> >> > > > > > describe that.
> >> > > > >
> >> > > > > By "that" you must mean that the physical is a user facing port.
> >> > > >
> >> > > > Can you please describe the difference between 'PF port' and
> >> > > > 'physical port of include/uapi/linux/devlink.h'? I must have
> >> > > > missed this crisp definition in discussion between you and
> >> > > > Jiri. I am in meantime checking the thread.
> >> > >
> >> > > Perhaps start with the cover letter which includes an ASCII drawing?
> >> > >
> >> > > Using Mellanox nomenclature - PF port is a "representor" for the
> >> > > PF which may be on another Host (SmartNIC or multihost). It's
> >> > > pretty much the same thing as a VF port/"representor".
> >> > >
> >> > Yes. We are aligned here. :-)
> >> > I see your point, where in multi-host scenario, a physical port may
> >> > be 1, but PF ports are 4, because of 4 PFs for 4 hosts.
> >> > (just an example of 4 hosts with their own mac address sharing 1
> >> > physical port).
> >> >
> >> > When there is no multihost and one to one mapping between a PF and
> >> > physical links, there is some overlap between PF port and physical
> >> > port attributes.
> >> > I believe, such overlap is fine as long as we have unique indices for the
> ports.
> >> >
> >> > So I am ok to have flavours as physical/cpu/dsa/pf/vf/mdev/switchport.
> >> > (last 4 as new port flavours).
> >> >
> >> > > Physical port is the hole on the panel of the adapter where cable
> goes.
> >>
> >> So my take away from above discussion are:
> >> 1. Following new port flavours should be added
> pci_pf/pci_vf/mdev/switchport.
> >> a. Switchport indicates port on the eswitch. Normally this port has rep-
> netdev attached to it.
> >
> >I don't understand the "switchport". Surely physical ports are also
> >attached to the eswitch? And one of the main purpose of adding the
> >pci_pf/pci_vf flavours was to generate phys_port_name for the port
> >netdevs.
> >
> >Please don't use the term representor if possible. Representor for
> >most developers describes the way the netdev is implemented in the
> >driver, so for Mellanox and Netronome different ports will be
> >representors and non-representors. That's why I prefer port netdev
> >(attached to eswitch, has switch_id) and host netdev (PF/VF netdev,
> >vNIC, VSI, etc).
> >
> >> b. host side port flavours are pci_pf/pci_vf/mdev which may be
> >> connected to switchport
> >
> >See above, pci_pf/pci_vf are needed for phys_port_name generation.
>
> Yep, that makes sense.
>
>
> >
> >> 2. host side port flavours are not limited to Ethernet, as it is for devlink's
> port instance.
> >>
> >> 3. Each port is continue to be accessed using unique port index.
> >>
> >> 4. host side ports and switchport are control objects.
> >> a. switch side ports reside where current eswitch object of devlink
> >> instance reside b. for a given VF/PF/mdev such host side ports may be
> >> in hypervisor or VM or both depending on the privilege
> >>
> >> 5. eth.mac_address, rdma.port_guid can be programmed at host port
> >> flavours by extending as $ devlink port param set...
> >> (similar to devlink dev param set)
> >
> >You can keep restating that's your position, but I have *not* conceded
> >to that.
>
> I'm also not convinced that host dummy ports are good idea to hold these.
>
>
I didn't understand what do you mean my dummy port.
Can you explain what is wrong in programming host port params using host_port object?
Few questions are unanswered in my past 2 or 3 emails.
Can you please go through them?
Can you point to some example switch API where you program host params at switch?

> >
> >> 6. more host port params can be added in future when user need arise
> >>
> >> 7. rep-netdev continue to be eswitch (switchport) representor at the
> switch side.
> >> a. Hence rep-netdev cannot be used for programming host port's
> parameters.
> >>
> >> 8. eswitch devlink instance knows when VF/PF/mdev's switchport are
> created/removed.
> >> Hence, those will be created/deleted by eswitch.
> >> Similarly for host port flavours too.
> >>
> >> Does it look fine? Did I miss something?
> >> We would like to progress on incremental patches for item-4 and any
> >> prep work needed to reach to item-4.