Re: [PATCH v19 06/21] s390x/cpu topology: interception of PTF instruction

[Pierre Morel <pmorel@xxxxxxxxxxxxx>]

On 4/4/23 09:41, Cédric Le Goater wrote:
> On 4/3/23 18:28, 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@xxxxxxxxxxxxx>
> > ---
> >   include/hw/s390x/s390-virtio-ccw.h |  6 ++++
> >   hw/s390x/cpu-topology.c            | 56 ++++++++++++++++++++++++++++--
> >   target/s390x/kvm/kvm.c             | 11 ++++++
> >   3 files changed, 71 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/hw/s390x/s390-virtio-ccw.h 
> > b/include/hw/s390x/s390-virtio-ccw.h
> > index ea10a6c6e1..9aa9f48bd0 100644
> > --- a/include/hw/s390x/s390-virtio-ccw.h
> > +++ b/include/hw/s390x/s390-virtio-ccw.h
> > @@ -31,6 +31,12 @@ struct S390CcwMachineState {
> >       bool vertical_polarization;
> >   };
> >   +#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 1d672d4d81..eec6c9a896 100644
> > --- a/hw/s390x/cpu-topology.c
> > +++ b/hw/s390x/cpu-topology.c
> > @@ -26,8 +26,6 @@
> >    * .smp: keeps track of the machine topology.
> >    * .list: queue the topology entries inside which
> >    *        we keep the information on the CPU topology.
> > - * .polarization: the current subsystem polarization
> > - *
>
> Please remove from patch 3 instead.


Yes of course

Thanks,

Pierre


> >    */
> >   S390Topology s390_topology = {
> >       /* will be initialized after the cpu model is realized */
> > @@ -86,6 +84,57 @@ 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)
> > +{
> > +    struct S390CcwMachineState *s390ms = 
> > S390_CCW_MACHINE(current_machine);
> > +    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:
> > +        if (s390ms->vertical_polarization == !!fc) {
> > +            env->regs[r1] |= S390_PTF_REASON_DONE;
> > +            setcc(cpu, 2);
> > +        } else {
> > +            s390ms->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);
> > +    }
> > +}
> > +
> >   /**
> >    * s390_topology_reset:
> >    *
> > @@ -94,7 +143,10 @@ static void s390_topology_init(MachineState *ms)
> >    */
> >   void s390_topology_reset(void)
> >   {
> > +    struct S390CcwMachineState *s390ms = 
> > S390_CCW_MACHINE(current_machine);
> > +
> >       s390_cpu_topology_set_changed(false);
> > +    s390ms->vertical_polarization = false;
> >   }
> >     /**
> > diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c
> > index bc953151ce..fb63be41b7 100644
> > --- a/target/s390x/kvm/kvm.c
> > +++ b/target/s390x/kvm/kvm.c
> > @@ -96,6 +96,7 @@
> >     #define PRIV_B9_EQBS                    0x9c
> >   #define PRIV_B9_CLP                     0xa0
> > +#define PRIV_B9_PTF                     0xa2
> >   #define PRIV_B9_PCISTG                  0xd0
> >   #define PRIV_B9_PCILG                   0xd2
> >   #define PRIV_B9_RPCIT                   0xd3
> > @@ -1464,6 +1465,13 @@ static int kvm_mpcifc_service_call(S390CPU 
> > *cpu, struct kvm_run *run)
> >       }
> >   }
> >   +static void kvm_handle_ptf(S390CPU *cpu, struct kvm_run *run)
> > +{
> > +    uint8_t r1 = (run->s390_sieic.ipb >> 20) & 0x0f;
> > +
> > +    s390_handle_ptf(cpu, r1, RA_IGNORED);
> > +}
> > +
> >   static int handle_b9(S390CPU *cpu, struct kvm_run *run, uint8_t ipa1)
> >   {
> >       int r = 0;
> > @@ -1481,6 +1489,9 @@ static int handle_b9(S390CPU *cpu, struct 
> > kvm_run *run, uint8_t ipa1)
> >       case PRIV_B9_RPCIT:
> >           r = kvm_rpcit_service_call(cpu, run);
> >           break;
> > +    case PRIV_B9_PTF:
> > +        kvm_handle_ptf(cpu, run);
> > +        break;
> >       case PRIV_B9_EQBS:
> >           /* just inject exception */
> >           r = -1;