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

Parav Pandit
2019-03-21T17:44:42Z

> -----Original Message-----
> From: Jiri Pirko <jiri@resnulli.us>
> Sent: Thursday, March 21, 2019 12:24 PM
> To: Parav Pandit <parav@mellanox.com>
> Cc: Jakub Kicinski <jakub.kicinski@netronome.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
>
> Thu, Mar 21, 2019 at 05:50:37PM CET, parav@mellanox.com wrote:
> >
> >
> >> -----Original Message-----
> >> From: Jiri Pirko <jiri@resnulli.us>
> >> Sent: Thursday, March 21, 2019 11:16 AM
> >> To: Parav Pandit <parav@mellanox.com>
> >> Cc: Jakub Kicinski <jakub.kicinski@netronome.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
> >>
> >> Thu, Mar 21, 2019 at 04:03:58PM CET, parav@mellanox.com wrote:
> >> >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.
> >>
> >> It's a port for a VF host port which is not actually in the host but in the
> vm.
> >> Very confusing.
> >>
> >It is the vf_ctrl flavour. I don't see it any different than rep-netdev.
> >rep-netdev is not that confusing to us that represent eswitch vport.
> >Why vf_ctrl flavour port that represents otherside of the pipe as you have
> shown in example?
> >Why it that confusing?
>
> Because sometimes it is there only once (PF), sometimes twice (VF) - and one
> of these is kind-of zombie.
>
I gave the example in email that contains description yesterday.
You didn't respond to it.
So repeating here.
Can you please point what looks like zombie below?

$ devlink port show
pci/0000:05:00.0/0 eth netdev repndev_pf0_p0 flavour physical switch_id 00154d130d2f
pci/0000:05:00.0/1 eth netdev repndev_pf0_p1 flavour physical switch_id 00154d130d2f
pci/0000:05:00.0/10001 eth netdev repndev_pf0_vf_1 flavour switchport switch_id 00154d130d2f peer pci/0000:05:00.0/1
pci/0000:05:00.0/10002 eth netdev repndev_pf0_p0_mdev_8000 flavour switchport switch_id 00154d130d2f peer mdev/uuidX/0

pci/0000:05:00.0/1 eth netdev flavour vf_ctrl vf 1
mdev/uuidX/0 eth netdev flavour mdev_ctrl

> >
> >
> >> >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.