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

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Date:   Mon, 18 Mar 2019 13:11:54 +0100
From:   Jiri Pirko <jiri@...nulli.us>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>
Cc:     Parav Pandit <parav@...lanox.com>,
        "Samudrala, Sridhar" <sridhar.samudrala@...el.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "oss-drivers@...ronome.com" <oss-drivers@...ronome.com>
Subject: Re: [PATCH net-next v2 4/7] devlink: allow subports on devlink PCI
 ports

Fri, Mar 15, 2019 at 09:44:54PM CET, jakub.kicinski@...ronome.com wrote:
>On Fri, 15 Mar 2019 21:08:14 +0100, Jiri Pirko wrote:
>> >> IIUC, Jiri/Jakub are proposing creation of 2 devlink objects for each port -
>> >> host facing ports and switch facing ports. This is in addition to the netdevs
>> >> that are created today.
>
>To be clear I'm not in favour of the dual-object proposal.
>
>> >I am not proposing any different.
>> >I am proposing only two changes.
>> >1. control hostport params via referring hostport (not via indirect peer)  
>> 
>> Not really possible. If you passthrough VF into VM, the hostport goes
>> along with it.
>> 
>> >2. flavour should not be vf/pf, flavour should be hostport, switchport.
>> >Because switch is flat and agnostic of pf/vf/mdev.  
>> 
>> Not sure. It's good to have this kind of visibility.
>
>Yes, this subthread honestly makes me go from 60% sure to 95% sure we
>shouldn't do the dual object thing :(  Seems like Parav is already
>confused by it and suggests host port can exist without switch port :(

Although I understand your hesitation, the host ports are also
associated with the asic and should be under the devlink instance.
It is just a matter of proper documentation and clear code to avoid
confusions.


>
>> >> Are you suggesting that all the devlink objects should be visible only at the
>> >> hypervisor layer?
>> >>   
>> >Of course not.
>> >
>> >Ports and params controlled by hypervisor should be exposed at hypervisor/eswitch wherever its parent devlink instance exist.
>> >Ports which should be visible inside a VM should be exposed inside a VM.
>> >So for a given VF,
>> >
>> >If eswitch is at hypervisor level,
>> >$ devlink port show
>> >pci/0000:05:00.0/10002 eth netdev flavour switchport switch_id 00154d130d2f peer pci/0000:05:10.1/0
>> >pci/0000:05:10.1/0 eth netdev flavour hostport switch_id 00154d130d2f peer pci/0000:05:00.0/10002
>> >
>> >where VF is enumerated,
>> >$ devlink port show
>> >pci/0000:05:10.1/0 eth netdev flavour hostport  
>> 
>> So this is how it looks like in VM, right?
>> 
>> >This is because unprivileged VF doesn't have visibility to eswitch and its links.
>