Re: [PATCH v9 22/22] s390: doc: detailed specifications for AP virtualization

Cornelia Huck
2018-08-22T07:38:30Z

On Tue, 21 Aug 2018 20:54:49 +0200
Halil Pasic <pasic@linux.ibm.com> wrote:

> On 08/20/2018 10:16 PM, Tony Krowiak wrote:
> >> Does the SIE complain if you specify a control
> >> domain that the host does not have access to (I'd guess so)?
> >
> > The SIE does not complain if you specify a domain to which the host - or a
> > lower level guest - does not have access. The firmware performs a logical
> > AND of the guest's and hosts's - or lower level guest's - APMs, AQMs and ADMs
>
> Rather a bit-wise AND, I guess (of the same type masks corresponding to Guest 1 and
> Guest 2). The result of a logical AND is a logical value (true or false) as
> far as I remember.
>
> > to create effective masks EAPM, EAQM and EADM. Only devices corresponding to
> > the bits set in the EAPM, EAQM and EADM will be accessible by the guest.
>
> I'm not sure what is the intended meaning of 'the SIE complains'. If it means
> getting out of (SIE when interpreting lets say an NQAP under the discussed
> circumstances) with some sort of error code, I think Tony's answer, ' SIE does not complain'
> makes a lot of sense. It's the guest that's is trying to stretch further than
> the blanket reaches, and it's the guest that needs to be educated on this fact.

Yep, that's what I meant. If the hypervisor can call the SIE with that
config, but the guest gets an error if it tries to use something that
it cannot use, that's fine.