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

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

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@linux.ibm.com>
>> ---
>>   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;
>