Re: [PATCH v15 06/11] s390x/cpu topology: interception of PTF instruction

[Pierre Morel]

On 2/6/23 12:38, Thomas Huth wrote:
> On 01/02/2023 14.20, Pierre Morel wrote:
> > When the host supports the CPU topology facility, the PTF
> > instruction with function code 2 is interpreted by the SIE,
> > provided that the userland hypervizor activates the interpretation
>
> s/hypervizor/hypervisor/

grr, I was pretty sure you already said that to me and I did change 
it... seems I did not.

done now.

> > by using the KVM_CAP_S390_CPU_TOPOLOGY KVM extension.
> >
> > The PTF instructions with function code 0 and 1 are intercepted
> > and must be emulated by the userland hypervizor.
>
> dito

yes, thx.

> > During RESET all CPU of the configuration are placed in
> > horizontal polarity.
> >
> > Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> > ---
> ...
> >   /**
> >    * s390_topology_reset:
> >    *
> >    * Generic reset for CPU topology, calls s390_topology_reset()
> >    * s390_topology_reset() to reset the kernel Modified Topology
> >    * change record.
> > + * Then set global and all CPUs polarity to POLARITY_HORIZONTAL.
>
> You describe here already what's going to happen...
>
> >    */
> >   void s390_topology_reset(void)
> >   {
> >       s390_cpu_topology_reset();
> > +    /* Set global polarity to POLARITY_HORIZONTAL */
>
> ... then here again ...
>
> > +    s390_topology.polarity = POLARITY_HORIZONTAL;
>
> ... and the code is (fortunately) also very self-exaplaining...
>
> > +    /* Set all CPU polarity to POLARITY_HORIZONTAL */
> > +    s390_topology_set_cpus_polarity(POLARITY_HORIZONTAL);
>
> ... so I'd rather drop the two comments within the function body.

OK

> >   }
>
> (rest of the patch looks fine to me)
>
>   Thomas

Thanks.

Regards,
Pierre


--
Pierre Morel
IBM Lab Boeblingen