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

[Cornelia Huck]

On Tue, 21 Aug 2018 20:54:49 +0200
Halil Pasic <pasic@xxxxxxxxxxxxx> wrote:

> On 08/20/2018 10:16 PM, Tony Krowiak wrote:
> >> DoesÂtheÂSIEÂcomplainÂifÂyouÂspecifyÂaÂcontrol
> >> domainÂthatÂtheÂhostÂdoesÂnotÂhaveÂaccessÂtoÂ(I'dÂguessÂso)?  
> > 
> > TheÂSIEÂdoesÂnotÂcomplainÂifÂyouÂspecifyÂaÂdomainÂtoÂwhichÂtheÂhostÂ-ÂorÂa
> > lowerÂlevelÂguestÂ-ÂdoesÂnotÂhaveÂaccess.ÂTheÂfirmwareÂperformsÂaÂlogical
> > 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.
> 
> > toÂcreateÂeffectiveÂmasksÂEAPM,ÂEAQMÂandÂEADM.ÂOnlyÂdevicesÂcorrespondingÂto
> > theÂbitsÂsetÂinÂtheÂEAPM,ÂEAQMÂandÂEADMÂwillÂbeÂaccessibleÂbyÂtheÂguest.  
> 
> 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.