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From: Cornelia Huck <cohuck@redhat.com>
Subject: Re: [PATCH v9 22/22] s390: doc: detailed specifications for AP
 virtualization
Date: Wed, 22 Aug 2018 12:09:39 +0200
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To: Harald Freudenberger <freude@linux.ibm.com>
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On Wed, 22 Aug 2018 09:04:13 +0200
Harald Freudenberger <freude@linux.ibm.com> wrote:

> Well, sooner or later this has to work. Yesterday we tested the control
> domain thing with trying to pull some simple data from a 'controlled' domain
> to the TKE - doesn't work with a Linux LPAR. I will investigate the details in the
> next weeks. However, long-term it should be possible to run scenarios
> like having one KVM guest control all the domains used by other KVM guests.
> With respect to the KVM vfio driver, currently there should be just the
> rule that for a guest the control domain mask should be equal or a superset
> of the usage domain mask. This is by convention as the architecture is
> not so clear here, but this is enforced on every place which deals with
> usage and control domains (SE, TKE).

Thanks for the update; this makes me think we really should fiddle with
the masks in the kernel (as opposed to doing it higher up in the stack).