Re: Upstream QEMU guest support policy ? Re: [PATCH v3 0/2] spapr: Use vIOMMU translation for virtio by default

[David Gibson]

On Wed, Mar 11, 2020 at 03:33:59AM -0400, Michael S. Tsirkin wrote:
> On Wed, Mar 11, 2020 at 12:12:47PM +1100, David Gibson wrote:
> > I am wondering if we have to introduce an "svm=on" flag anyway.  It's
> > pretty ugly, since all it would be doing is changing defaults here and
> > there for compatibilty with a possible future SVM transition, but
> > maybe it's the best we can do :/.
> 
> Frankly I'm surprised there's no way for the hypervisor to block VM
> transition to secure mode. To me an inability to disable DRM looks like
> a security problem.

Uh.. I don't immediately see how it's a security problem, though I'm
certainly convinced it's a problem in other ways.

> Does not the ultravisor somehow allow
> enabling/disabling this functionality from the hypervisor?

Not at present, but as mentioned on the other thread, Paul and I came
up with a tentative plan to change that.

> It would be
> even better if the hypervisor could block the guest from poking at the
> ultravisor completely but I guess that would be too much to hope for.

Yeah, probably :/.

-- 
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

signature.asc
Description: PGP signature