netdev - Re: [PATCH net-next v2 8/8] netdevsim: Add support for add and delete PCI SF port

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Message-ID: <5cd529c8-cd55-b270-7f3c-227ef957b6e8@gmail.com>
Date:   Fri, 18 Sep 2020 09:23:42 -0600
From:   David Ahern <dsahern@...il.com>
To:     Parav Pandit <parav@...dia.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Cc:     Jiri Pirko <jiri@...dia.com>
Subject: Re: [PATCH net-next v2 8/8] netdevsim: Add support for add and delete
 PCI SF port

On 9/17/20 10:41 PM, Parav Pandit wrote:
> Hi David,
> 
>> From: David Ahern <dsahern@...il.com>
>> Sent: Friday, September 18, 2020 9:08 AM
>>
>> On 9/17/20 9:29 PM, Parav Pandit wrote:
>>>>> Examples:
>>>>>
>>>>> Create a PCI PF and PCI SF port.
>>>>> $ devlink port add netdevsim/netdevsim10/10 flavour pcipf pfnum 0 $
>>>>> devlink port add netdevsim/netdevsim10/11 flavour pcisf pfnum 0
>>>>> sfnum
>>>>> 44 $ devlink port show netdevsim/netdevsim10/11
>>>>> netdevsim/netdevsim10/11: type eth netdev eni10npf0sf44 flavour
>>>>> pcisf
>>>> controller 0 pfnum 0 sfnum 44 external true splittable false
>>>>>   function:
>>>>>     hw_addr 00:00:00:00:00:00 state inactive
>>>>>
>>>>> $ devlink port function set netdevsim/netdevsim10/11 hw_addr
>>>>> 00:11:22:33:44:55 state active
>>>>>
>>>>> $ devlink port show netdevsim/netdevsim10/11 -jp {
>>>>>     "port": {
>>>>>         "netdevsim/netdevsim10/11": {
>>>>>             "type": "eth",
>>>>>             "netdev": "eni10npf0sf44",
>>>>
>>>> I could be missing something, but it does not seem like this patch
>>>> creates the netdevice for the subfunction.
>>>>
>>> The sf port created here is the eswitch port with a valid switch id similar to PF
>> and physical port.
>>> So the netdev created is the representor netdevice.
>>> It is created uniformly for subfunction and pf port flavours.
>>
>> To be clear: If I run the devlink commands to create a sub-function, `ip link
>> show` should list a net_device that corresponds to the sub-function?
> 
> In this series only representor netdevice corresponds to sub-function will be visible in ip link show, i.e. eni10npf0sf44.
> 
> Netdevsim is only simulating the eswitch side or control path at present for pf/vf/sf ports.
> So other end of this port (netdevice/rdma device/vdpa device) are not yet created.
> 
> Subfunction will be anchored on virtbus described in RFC [1], which is not yet in-kernel yet.
> Grep for "every SF a device is created on virtbus" to jump to this part of the long RFC.
> 
> [1] https://lore.kernel.org/netdev/20200519092258.GF4655@nanopsycho/
> 

Thanks for the reference. I have seen that. I am interested in this idea
of creating netdevs for 'slices' of an asic or nic, but it is not clear
to me how it connects end to end. Will you be able to create a
sub-function based netdevice, assign it limited resources from the nic
and then assign that netdevice to a container for example?