Re: [virtio-dev] Re: [PATCH 0/5] virtio: introduce SUSPEND bit and vq state

Zhu, Lingshan
2023-09-20T06:06:20Z

On 9/19/2023 2:49 AM, Michael S. Tsirkin wrote:
> On Mon, Sep 18, 2023 at 06:41:55PM +0000, Parav Pandit wrote:
>>> Please refer to the code for setting FEATURES_OK.
>> It wont work when one needs to suspend the device.
>> There is no point of doing such work over registers as fundamental framework is over the AQ.
> Well not really. It's over admin commands. When these were built the
> intent always was that it's possible to use admin commands through
> another interface, other than admin queue. Is there a problem
> implementing admin commands over a memory BAR? For example, I can see
> an "admin command" capability pointing at a BAR where
> commands are supplied, and using a new group type referring to
> device itself.
I am not sure, if a bar cap would be implemented as a proxy for the admin vq
based live migration. then the problems of admin vq LM that we have
discussed
still exist. the bar is only a proxy, doesn't fix anything. and even larger
side channel attacking surface: vf-->pf-->vf