Re: [PATCH v4 1/7] s390: ap: kvm: add PQAP interception for AQIC

[Pierre Morel]

On 28/02/2019 15:14, Pierre Morel wrote:
> On 28/02/2019 14:52, Cornelia Huck wrote:
> > On Thu, 28 Feb 2019 14:16:09 +0100
> > Pierre Morel <pmorel@xxxxxxxxxxxxx> wrote:
> >
> > > On 28/02/2019 12:22, Cornelia Huck wrote:
> >
> > > > So, to summarize, the function should do:
> > > > - Is userspace supposed to emulate everything (!ECA_APIE)? Return
> > > > ÂÂÂ -EOPNOTSUPP to hand control to it.
> > > > - We are now interpreting the instruction in KVM. Do common checks
> > > > ÂÂÂ (PSTATE etc.) and inject exceptions, if needed.
> > > > - Now look at the fc; if there's a handler for it, call that; if not
> > > > ÂÂÂ (case does not attempt to call a specific handler, or no handler
> > > > ÂÂÂ registered), inject a specification exception. (Do we want 
> > > > pre-checks
> > > > ÂÂÂ like for facility 65 here, or in the handler?)
> > > >
> > > > That response code 0x01 thingy probably needs to go into the specific
> > > > handler function, if anywhere (don't know the semantics, sorry).
> > >
> > > What do you mean with specific handler function?
> > >
> > > If you mean a switch around the FC with static function's call, I agree,
> > > if you mean a jump into a hook I do not agree.
> >
> > Ah, ok; so each case (that we want to handle) should call into a
> > subhandler that does
> > {
> > ÂÂÂÂ(... check things like facilities ...)
> > ÂÂÂÂif (!specific_hook)
> > ÂÂÂÂÂÂÂ inject_specif_excp_and_return();
> > ÂÂÂÂret = specific_hook();
> > ÂÂÂÂif (ret)
> > ÂÂÂÂÂÂÂ set_resp_code_0x01(); // or in specific_hook()?
> > }
> >
> > ?
>
> Yes something in this direction.

Sorry, after reflection, no, we do not want to change the previous 
behavior so we only handle the AQIC case.

Regards,
Pierre


--
Pierre Morel
Linux/KVM/QEMU in BÃblingen - Germany