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

[Pierre Morel <pmorel@linux.ibm.com>]

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);
>> +    }
>> +}
>> +
> [...]
>