Re: [PATCH v9 08/10] target/s390x: interception of PTF instruction

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

On 9/9/22 18:50, Janis Schoetterl-Glausch wrote:
> On Fri, 2022-09-02 at 09:55 +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 hypervizor 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 hypervizor.
>>
>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> 
> Reviewed-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>

Thanks

> 
> See note below.
>> ---
>>   hw/s390x/cpu-topology.c            | 52 ++++++++++++++++++++++++++++++
>>   include/hw/s390x/s390-virtio-ccw.h |  6 ++++
>>   target/s390x/kvm/kvm.c             | 13 ++++++++
>>   3 files changed, 71 insertions(+)
>>
>> diff --git a/hw/s390x/cpu-topology.c b/hw/s390x/cpu-topology.c
>> index b6bf839e40..7dcaa28ca3 100644
>> --- a/hw/s390x/cpu-topology.c
>> +++ b/hw/s390x/cpu-topology.c
>> @@ -20,6 +20,58 @@
>>   #include "hw/s390x/s390-virtio-ccw.h"
>>   #include "hw/s390x/cpu-topology.h"
>>   #include "migration/vmstate.h"
>> +#include "target/s390x/cpu.h"
>> +#include "hw/s390x/s390-virtio-ccw.h"
>> +
>> +/*
>> + * s390_handle_ptf:
>> + *
>> + * @register 1: contains the function code
>> + *
>> + * Function codes 0 and 1 handle the CPU polarization.
>> + * We assume an horizontal topology, the only one supported currently
>> + * by Linux, consequently we answer to function code 0, requesting
>> + * horizontal polarization that it is already the current polarization
>> + * and reject vertical polarization request without further explanation.
>> + *
>> + * 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];
>> +    uint8_t fc = reg & S390_TOPO_FC_MASK;
>> +
>> +    if (!s390_has_feat(S390_FEAT_CONFIGURATION_TOPOLOGY)) {
>> +        s390_program_interrupt(env, PGM_OPERATION, ra);
>> +        return;
> 
> I'm either expecting this function to return -1 here...
>> +    }
>> +
>> +    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 0:    /* Horizontal polarization is already set */
>> +        env->regs[r1] |= S390_PTF_REASON_DONE;
>> +        setcc(cpu, 2);
>> +        break;
>> +    case 1:    /* Vertical polarization is not supported */
>> +        env->regs[r1] |= S390_PTF_REASON_NONE;
>> +        setcc(cpu, 2);
>> +        break;
>> +    default:
>> +        /* Note that fc == 2 is interpreted by the SIE */
>> +        s390_program_interrupt(env, PGM_SPECIFICATION, ra);
>> +    }
>> +}
> 
> [...]
>>   
>> +static int 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);
> 
> ... and this being returned here...
>> +
>> +    return 0;
> 
> ... or this function being void.
>> +}


Yes right, thanks

Regards,
Pierre


-- 
Pierre Morel
IBM Lab Boeblingen