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

[Cédric Le Goater]

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.

>    */
>   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;