RE: [RFC net-next 0/8] Introducing subdev bus and devlink extension

From: Parav Pandit <parav@nvidia.com>
To: Yunsheng Lin <linyunsheng@huawei.com>, Jakub Kicinski <kuba@kernel.org>
Cc: moyufeng <moyufeng@huawei.com>,
	Jakub Kicinski <jakub.kicinski@netronome.com>,
	Jiri Pirko <jiri@resnulli.us>, Or Gerlitz <gerlitz.or@gmail.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"michal.lkml@markovi.net" <michal.lkml@markovi.net>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	Jiri Pirko <jiri@nvidia.com>,
	Salil Mehta <salil.mehta@huawei.com>,
	"lipeng (Y)" <lipeng321@huawei.com>,
	Guangbin Huang <huangguangbin2@huawei.com>,
	"shenjian15@huawei.com" <shenjian15@huawei.com>,
	"chenhao (DY)" <chenhao288@hisilicon.com>,
	Jiaran Zhang <zhangjiaran@huawei.com>,
	"linuxarm@openeuler.org" <linuxarm@openeuler.org>
Subject: RE: [RFC net-next 0/8] Introducing subdev bus and devlink extension
Date: Wed, 9 Jun 2021 11:59:33 +0000	[thread overview]
Message-ID: <DM8PR12MB5480F577E5F02105B8C1FE9BDC369@DM8PR12MB5480.namprd12.prod.outlook.com> (raw)
In-Reply-To: <d54ae715-8634-c983-1602-8cd8dea2a5e2@huawei.com>


> From: Yunsheng Lin <linyunsheng@huawei.com>
> Sent: Wednesday, June 9, 2021 4:35 PM
> 
> On 2021/6/9 17:38, Parav Pandit wrote:
> >
> >> From: Yunsheng Lin <linyunsheng@huawei.com>
> >> Sent: Wednesday, June 9, 2021 2:46 PM
> >>
> > [..]
> >
> >>>> Is there any reason why VF use its own devlink instance?
> >>>
> >>> Primary use case for VFs is virtual environments where guest isn't
> >>> trusted, so tying the VF to the main devlink instance, over which
> >>> guest should have no control is counter productive.
> >>
> >> The security is mainly about VF using in container case, right?
> >> Because VF using in VM, it is different host, it means a different
> >> devlink instance for VF, so there is no security issue for VF using in VM
> case?
> >> But it might not be the case for VF using in container?
> > Devlink instance has net namespace attached to it controlled using devlink
> reload command.
> > So a VF devlink instance can be assigned to a container/process running in a
> specific net namespace.
> >
> > $ ip netns add n1
> > $ devlink dev reload pci/0000:06:00.4 netns n1
> >                                      ^^^^^^^^^^^^^
> >                                      PCI VF/PF/SF.
> 
> Could we create another devlink instance when the net namespace of
> devlink port instance is changed? 
Net namespace of (a) netdevice (b) rdma device (c) devlink instance can be changed.
Net namespace of devlink port cannot be changed.

> It may seems we need to change the net
> namespace based on devlink port instance instead of devlink instance.
> This way container case seems be similiar to the VM case?
I mostly do not understand the topology you have in mind or if you explained previously I missed the thread.
In your case what is the flavour of a devlink port?

> 
> >
> >> Also, there is a "switch_id" concept from jiri's example, which seems
> >> to be not implemented yet?
> >
> > switch_id is present for switch ports in [1] and documented in [2].
> >
> > [1] /sys/class/net/representor_netdev/phys_switch_id.
> > [2]
> https://www.kernel.org/doc/Documentation/networking/switchdev.txt "
> Switch ID"
> 
> Thanks for info.
> I suppose we could use "switch_id" to indentify a eswitch since "switch_id is
> present for switch ports"?
> Where does the "switch_id" of switch port come from? Is it from FW?
> Or the driver generated it?
> 
> Is there any rule for "switch_id"? Or is it vendor specific?
> 
> >
It should be unique enough, usually generated out of board serial id or other fields such as vendor OUI that makes it fairly unique.