On Tue, Jun 09, 2020 at 08:44:02AM +0200, Cornelia Huck wrote: > On Mon, 8 Jun 2020 19:00:45 +0200 > Halil Pasic <pa...@linux.ibm.com> wrote: > > > > > I'm also not 100% sure about migration... would it make sense to > > > discuss all of this in the context of the cross-arch patchset? It seems > > > power has similar issues. > > > > > > > I'm going to definitely have a good look at that. What I think special > > about s390 is that F_ACCESS_PLATFORM is hurting us because all IO needs > > to go through ZONE_DMA (this is a problem of the implementation that > > stemming form a limitation of the DMA API, upstream didn't let me > > fix it). > > My understanding is that power runs into similar issues, but I don't > know much about power, so I might be entirely wrong :)
Sort of, but not to the same extent, I think.
[snip]
> > > (Can we disallow transition to pv if it is off? Maybe with the machine
> > > property approach from the cross-arch patchset?)
> >
> > No we can't disallow transition because for hotplug that already
> > happened.
>
> I mean, can a virtio devices without IOMMU_PLATFORM act as a transition
> blocker (i.e. an attempt by a guest to move to pv would fail?)
This might be possible, but I suspect having to explicitly say you
want pv support, then having it validate virtio (and anything else it
needs) will give a better UX.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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