Re: [PATCH v20 06/21] s390x/cpu topology: interception of PTF instruction

[Pierre Morel]

On 5/4/23 13:03, Nina Schoetterl-Glausch wrote:
> On Tue, 2023-04-25 at 18:14 +0200, 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 hypervisor activates the interpretation
> > 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 hypervisor.
> >
> > During RESET all CPU of the configuration are placed in
> > horizontal polarity.
> >
> > Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> Reviewed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>

Thanks


> See nit below.
> > ---
> >   include/hw/s390x/s390-virtio-ccw.h |  6 ++++
> >   hw/s390x/cpu-topology.c            | 51 ++++++++++++++++++++++++++++++
> >   target/s390x/kvm/kvm.c             | 11 +++++++
> >   3 files changed, 68 insertions(+)
> >
> > diff --git a/include/hw/s390x/s390-virtio-ccw.h 
> > b/include/hw/s390x/s390-virtio-ccw.h
> > index 9bba21a916..c1d46e78af 100644
> > --- a/include/hw/s390x/s390-virtio-ccw.h
> > +++ b/include/hw/s390x/s390-virtio-ccw.h
> > @@ -30,6 +30,12 @@ struct S390CcwMachineState {
> >       uint8_t loadparm[8];
> >   };
> >   
> > +#define S390_PTF_REASON_NONE (0x00 << 8)
> > +#define S390_PTF_REASON_DONE (0x01 << 8)
> > +#define S390_PTF_REASON_BUSY (0x02 << 8)
> > +#define S390_TOPO_FC_MASK 0xffUL
> > +void s390_handle_ptf(S390CPU *cpu, uint8_t r1, uintptr_t ra);
> > +
> >   struct S390CcwMachineClass {
> >       /*< private >*/
> >       MachineClass parent_class;
> > diff --git a/hw/s390x/cpu-topology.c b/hw/s390x/cpu-topology.c
> > index c98439ff7a..3c7bbff4bc 100644
> > --- a/hw/s390x/cpu-topology.c
> > +++ b/hw/s390x/cpu-topology.c
> > @@ -96,6 +96,56 @@ static void s390_topology_init(MachineState *ms)
> >       QTAILQ_INSERT_HEAD(&s390_topology.list, entry, next);
> >   }
> >   
> > +/*
> > + * s390_handle_ptf:
> > + *
> > + * @register 1: contains the function code
> > + *
> > + * Function codes 0 (horizontal) and 1 (vertical) define the CPU
> > + * polarization requested by the guest.
> > + *
> > + * Function code 2 is handling topology changes and is interpreted
> > + * by the SIE.
> > + */
> > +void s390_handle_ptf(S390CPU *cpu, uint8_t r1, uintptr_t ra)
> > +{
> > +    CPUS390XState *env = &cpu->env;
> > +    uint64_t reg = env->regs[r1];
> > +    int fc = reg & S390_TOPO_FC_MASK;
> > +
> > +    if (!s390_has_feat(S390_FEAT_CONFIGURATION_TOPOLOGY)) {
> > +        s390_program_interrupt(env, PGM_OPERATION, ra);
> > +        return;
> > +    }
> > +
> > +    if (env->psw.mask & PSW_MASK_PSTATE) {
> > +        s390_program_interrupt(env, PGM_PRIVILEGED, ra);
> > +        return;
> > +    }
> > +
> > +    if (reg & ~S390_TOPO_FC_MASK) {
> > +        s390_program_interrupt(env, PGM_SPECIFICATION, ra);
> > +        return;
> > +    }
> > +
> > +    switch (fc) {
> > +    case S390_CPU_POLARIZATION_VERTICAL:
> > +    case S390_CPU_POLARIZATION_HORIZONTAL:
> I'd give this a name.
> bool requested_vertical = !!fc;


OK, looks good, I change this


Thanks.

Regards,

Pierre

> > +        if (s390_topology.vertical_polarization == !!fc) {
> > +            env->regs[r1] |= S390_PTF_REASON_DONE;
> > +            setcc(cpu, 2);
> > +        } else {
> > +            s390_topology.vertical_polarization = !!fc;
> > +            s390_cpu_topology_set_changed(true);
> > +            setcc(cpu, 0);
> > +        }
> > +        break;
> > +    default:
> > +        /* Note that fc == 2 is interpreted by the SIE */
> > +        s390_program_interrupt(env, PGM_SPECIFICATION, ra);
> > +    }
> > +}
> > +
> [...]