Re: [PATCH v2] hw/s390x: Fix a possible crash with passed-through virtio devices

[Halil Pasic <pasic@linux.ibm.com>]

On Tue, 18 Nov 2025 10:19:56 -0500
Eric Farman <farman@linux.ibm.com> wrote:

> > So I think it would really make sense to prevent passing through
> > virtio-ccw devices with vfio-ccw. Eric what is your take?  
> 
> It's true that the only -supported- use case is passthrough DASD, and we allow other device types to
> be passed through. The only ones we fence off are what we know aren't going to work, like FCPs.

I think we can add virto-ccw to that known to not work list ;)

> IIRC
> we'd talked a few years ago about a plan for a more detailed allow-list of passthrough devices and
> configurations, but that fell off the back of the todo list. Short of dusting all that off, I don't
> know that blocking virtio-ccw from vfio is going to buy us anything that Thomas' patch doesn't
> already provide.

See your comment form later today :)

Would prevent ending up with a most likely dysfunctional device at best.

Regards,
Halil