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Date: Fri, 1 Feb 2019 11:42:14 +0100
From: Cornelia Huck <cohuck@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v2 5/6] s390x/pci: Drop release timer and
 replace it with a flag
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To: David Hildenbrand <david@redhat.com>
Cc: qemu-devel@nongnu.org, qemu-s390x@nongnu.org, Collin Walling <walling@linux.ibm.com>, Thomas Huth <thuth@redhat.com>, Christian Borntraeger <borntraeger@de.ibm.com>, Richard Henderson <rth@twiddle.net>, Pierre Morel <pmorel@linux.ibm.com>

On Fri, 1 Feb 2019 11:37:56 +0100
David Hildenbrand <david@redhat.com> wrote:

> On 01.02.19 11:08, Cornelia Huck wrote:
> > On Thu, 31 Jan 2019 22:21:01 +0100
> > David Hildenbrand <david@redhat.com> wrote:
> >   
> >> Thinking out loud:
> >>
> >> We should migrate the flag in the future. This is already a problem
> >> right now, as the timer is also not migrated.
> >>
> >> If the unplug request is sent and we migrate before the guest can react,
> >> the unplug would not happen.
> >>
> >> However, looks like migration of zpci devices is not implemented _at all_.  
> > 
> > Oh, joy.
> >   
> >>
> >> This does not matter for pci passthrough (main use case). But when
> >> wanting to use e.g. virtio-pci-net, things are shaky after migration.
> >>
> >> So this is future work.
> >>  
> > 
> > Hopefully folks running s390x guests are rather using virtio-ccw
> > devices anyway...
> > 
> > I agree that this needs to be taken care of on top of these changes.
> > Should we mark zpci devices unmigratable, or does it work for some
> > values of "work"?
> >   
> 
> It works if the guest never configures a zpci device I guess ... so I
> think this is pretty much broken. E.g. the state of the zpci device is
> not even migrated unless I am missing something.

Ok, that seems to call for marking zpci devices unmigratable...