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

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Date:   Wed, 9 Jun 2021 20:30:14 +0800
From:   Yunsheng Lin <linyunsheng@...wei.com>
To:     Parav Pandit <parav@...dia.com>, Jakub Kicinski <kuba@...nel.org>
CC:     moyufeng <moyufeng@...wei.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Jiri Pirko <jiri@...nulli.us>,
        Or Gerlitz <gerlitz.or@...il.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "michal.lkml@...kovi.net" <michal.lkml@...kovi.net>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        Jiri Pirko <jiri@...dia.com>,
        Salil Mehta <salil.mehta@...wei.com>,
        "lipeng (Y)" <lipeng321@...wei.com>,
        Guangbin Huang <huangguangbin2@...wei.com>,
        "shenjian15@...wei.com" <shenjian15@...wei.com>,
        "chenhao (DY)" <chenhao288@...ilicon.com>,
        Jiaran Zhang <zhangjiaran@...wei.com>,
        "linuxarm@...neuler.org" <linuxarm@...neuler.org>
Subject: Re: [RFC net-next 0/8] Introducing subdev bus and devlink extension

On 2021/6/9 19:59, Parav Pandit wrote:
>> From: Yunsheng Lin <linyunsheng@...wei.com>
>> Sent: Wednesday, June 9, 2021 4:35 PM
>>
>> On 2021/6/9 17:38, Parav Pandit wrote:
>>>
>>>> From: Yunsheng Lin <linyunsheng@...wei.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.

Yes, net namespace is changed based on the devlink instance, not
devlink port instance, *right now*.

> 
>> 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?

flavour of the devlink port instance is FLAVOUR_PHYSICAL or
FLAVOUR_VIRTUAL.

The reason I suggest to change the net namespace on devlink port
instance instead of devlink instance is：
I proposed that all the PF and VF in the same ASIC are registered to
the same devlink instance as flavour FLAVOUR_PHYSICAL or FLAVOUR_VIRTUAL
when there are in the same host and in the same net namespace.

If a VF's devlink port instance is unregistered from old devlink
instance in the old net namespace and registered to new devlink
instance in the new net namespace(create a new devlink instance if
needed) when devlink port instance's net namespace is changed, then
the security mentioned by jakub is not a issue any more?

> 
>>
>>>
>>>> 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.
> 
>