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

From: Parav Pandit <parav@nvidia.com>
To: "Samudrala, Sridhar" <sridhar.samudrala@intel.com>,
	David Ahern <dsahern@gmail.com>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"kuba@kernel.org" <kuba@kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Cc: Jiri Pirko <jiri@nvidia.com>
Subject: RE: [PATCH net-next v2 8/8] netdevsim: Add support for add and delete PCI SF port
Date: Fri, 18 Sep 2020 05:10:57 +0000	[thread overview]
Message-ID: <BY5PR12MB43225AA5A5E42E76C03F645BDC3F0@BY5PR12MB4322.namprd12.prod.outlook.com> (raw)
In-Reply-To: <0b11ae28-3868-ee9f-184a-8cb577f717fc@intel.com>

> From: Samudrala, Sridhar <sridhar.samudrala@intel.com>
> Sent: Friday, September 18, 2020 10:23 AM
> 
> 
> On 9/17/2020 9:41 PM, Parav Pandit wrote:
> > Hi David,
> >
> >> From: David Ahern <dsahern@gmail.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.
> 
> This should be OK if the eSwitch mode is changed to switchdev.
> But i think it should be possible to create a subfunction even in legacy mode
> where representor netdev is not created.

switch_id is optional attribute of the devlink port.
It is applicable only when it is eswitch port in switchdev mode.

> 
> >
> > 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/
> >