netdev - Re: [PATCH v7 net-next 4/4] netvsc: refactor notifier/event handling code to use the failover framework

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Message-ID: <CADGSJ20ge75T+ddxtUBT4d9m1i3=HLOAHJEoS7Cg0bqnXrutwA@mail.gmail.com>
Date:   Mon, 23 Apr 2018 12:44:39 -0700
From:   Siwei Liu <loseweigh@...il.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     Stephen Hemminger <stephen@...workplumber.org>,
        Jiri Pirko <jiri@...nulli.us>,
        Sridhar Samudrala <sridhar.samudrala@...el.com>,
        David Miller <davem@...emloft.net>,
        Netdev <netdev@...r.kernel.org>,
        virtualization@...ts.linux-foundation.org,
        virtio-dev@...ts.oasis-open.org,
        "Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
        Alexander Duyck <alexander.h.duyck@...el.com>,
        Jakub Kicinski <kubakici@...pl>,
        Jason Wang <jasowang@...hat.com>
Subject: Re: [PATCH v7 net-next 4/4] netvsc: refactor notifier/event handling
 code to use the failover framework

On Mon, Apr 23, 2018 at 10:56 AM, Michael S. Tsirkin <mst@...hat.com> wrote:
> On Mon, Apr 23, 2018 at 10:44:40AM -0700, Stephen Hemminger wrote:
>> On Mon, 23 Apr 2018 20:24:56 +0300
>> "Michael S. Tsirkin" <mst@...hat.com> wrote:
>>
>> > On Mon, Apr 23, 2018 at 10:04:06AM -0700, Stephen Hemminger wrote:
>> > > > >
>> > > > >I will NAK patches to change to common code for netvsc especially the
>> > > > >three device model.  MS worked hard with distro vendors to support transparent
>> > > > >mode, ans we really can't have a new model; or do backport.
>> > > > >
>> > > > >Plus, DPDK is now dependent on existing model.
>> > > >
>> > > > Sorry, but nobody here cares about dpdk or other similar oddities.
>> > >
>> > > The network device model is a userspace API, and DPDK is a userspace application.
>> >
>> > It is userspace but are you sure dpdk is actually poking at netdevs?
>> > AFAIK it's normally banging device registers directly.
>> >
>> > > You can't go breaking userspace even if you don't like the application.
>> >
>> > Could you please explain how is the proposed patchset breaking
>> > userspace? Ignoring DPDK for now, I don't think it changes the userspace
>> > API at all.
>> >
>>
>> The DPDK has a device driver vdev_netvsc which scans the Linux network devices
>> to look for Linux netvsc device and the paired VF device and setup the
>> DPDK environment.  This setup creates a DPDK failsafe (bondingish) instance
>> and sets up TAP support over the Linux netvsc device as well as the Mellanox
>> VF device.
>>
>> So it depends on existing 2 device model. You can't go to a 3 device model
>> or start hiding devices from userspace.
>
> Okay so how does the existing patch break that? IIUC does not go to
> a 3 device model since netvsc calls failover_register directly.
>
>> Also, I am working on associating netvsc and VF device based on serial number
>> rather than MAC address. The serial number is how Windows works now, and it makes
>> sense for Linux and Windows to use the same mechanism if possible.
>
> Maybe we should support same for virtio ...
> Which serial do you mean? From vpd?
>
> I guess you will want to keep supporting MAC for old hypervisors?
>
> It all seems like a reasonable thing to support in the generic core.

That's the reason why I chose explicit identifier rather than rely on
MAC address to bind/pair a device. MAC address can change. Even if it
can't, malicious guest user can fake MAC address to skip binding.

-Siwei


>
> --
> MST