Re: [PATCH v10 3/9] s390x/cpu_topology: resetting the Topology-Change-Report

[Pierre Morel]

On 10/27/22 11:58, Cédric Le Goater wrote:
> On 10/27/22 11:11, Pierre Morel wrote:
> > On 10/27/22 10:14, Thomas Huth wrote:
> > > On 12/10/2022 18.21, Pierre Morel wrote:
> > > > During a subsystem reset the Topology-Change-Report is cleared
> > > > by the machine.
> > > > Let's ask KVM to clear the Modified Topology Change Report (MTCR)
> > > >   bit of the SCA in the case of a subsystem reset.
> > > >
> > > > Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> > > > Reviewed-by: Nico Boehr <nrb@linux.ibm.com>
> > > > Reviewed-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
> > > > ---
> > > >   target/s390x/cpu.h           |  1 +
> > > >   target/s390x/kvm/kvm_s390x.h |  1 +
> > > >   hw/s390x/cpu-topology.c      | 12 ++++++++++++
> > > >   hw/s390x/s390-virtio-ccw.c   |  1 +
> > > >   target/s390x/cpu-sysemu.c    |  7 +++++++
> > > >   target/s390x/kvm/kvm.c       | 23 +++++++++++++++++++++++
> > > >   6 files changed, 45 insertions(+)
> > > >
> > > > diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
> > > > index d604aa9c78..9b35795ac8 100644
> > > > --- a/target/s390x/cpu.h
> > > > +++ b/target/s390x/cpu.h
> > > > @@ -825,6 +825,7 @@ void s390_enable_css_support(S390CPU *cpu);
> > > >   void s390_do_cpu_set_diag318(CPUState *cs, run_on_cpu_data arg);
> > > >   int s390_assign_subch_ioeventfd(EventNotifier *notifier, uint32_t 
> > > > sch_id,
> > > >                                   int vq, bool assign);
> > > > +void s390_cpu_topology_reset(void);
> > > >   #ifndef CONFIG_USER_ONLY
> > > >   unsigned int s390_cpu_set_state(uint8_t cpu_state, S390CPU *cpu);
> > > >   #else
> > > > diff --git a/target/s390x/kvm/kvm_s390x.h 
> > > > b/target/s390x/kvm/kvm_s390x.h
> > > > index aaae8570de..a13c8fb9a3 100644
> > > > --- a/target/s390x/kvm/kvm_s390x.h
> > > > +++ b/target/s390x/kvm/kvm_s390x.h
> > > > @@ -46,5 +46,6 @@ void kvm_s390_crypto_reset(void);
> > > >   void kvm_s390_restart_interrupt(S390CPU *cpu);
> > > >   void kvm_s390_stop_interrupt(S390CPU *cpu);
> > > >   void kvm_s390_set_diag318(CPUState *cs, uint64_t diag318_info);
> > > > +int kvm_s390_topology_set_mtcr(uint64_t attr);
> > > >   #endif /* KVM_S390X_H */
> > > > diff --git a/hw/s390x/cpu-topology.c b/hw/s390x/cpu-topology.c
> > > > index c73cebfe6f..9f202621d0 100644
> > > > --- a/hw/s390x/cpu-topology.c
> > > > +++ b/hw/s390x/cpu-topology.c
> > > > @@ -107,6 +107,17 @@ static void s390_topology_realize(DeviceState 
> > > > *dev, Error **errp)
> > > >       qemu_mutex_init(&topo->topo_mutex);
> > > >   }
> > > > +/**
> > > > + * s390_topology_reset:
> > > > + * @dev: the device
> > > > + *
> > > > + * Calls the sysemu topology reset
> > > > + */
> > > > +static void s390_topology_reset(DeviceState *dev)
> > > > +{
> > > > +    s390_cpu_topology_reset();
> > > > +}
> > > > +
> > > >   /**
> > > >    * topology_class_init:
> > > >    * @oc: Object class
> > > > @@ -120,6 +131,7 @@ static void topology_class_init(ObjectClass *oc, 
> > > > void *data)
> > > >       dc->realize = s390_topology_realize;
> > > >       set_bit(DEVICE_CATEGORY_MISC, dc->categories);
> > > > +    dc->reset = s390_topology_reset;
> > > >   }
> > > >   static const TypeInfo cpu_topology_info = {
> > > > diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
> > > > index aa99a62e42..362378454a 100644
> > > > --- a/hw/s390x/s390-virtio-ccw.c
> > > > +++ b/hw/s390x/s390-virtio-ccw.c
> > > > @@ -113,6 +113,7 @@ static const char *const reset_dev_types[] = {
> > > >       "s390-flic",
> > > >       "diag288",
> > > >       TYPE_S390_PCI_HOST_BRIDGE,
> > > > +    TYPE_S390_CPU_TOPOLOGY,
> > > >   };
> > > >   static void subsystem_reset(void)
> > > > diff --git a/target/s390x/cpu-sysemu.c b/target/s390x/cpu-sysemu.c
> > > > index 948e4bd3e0..707c0b658c 100644
> > > > --- a/target/s390x/cpu-sysemu.c
> > > > +++ b/target/s390x/cpu-sysemu.c
> > > > @@ -306,3 +306,10 @@ void s390_do_cpu_set_diag318(CPUState *cs, 
> > > > run_on_cpu_data arg)
> > > >           kvm_s390_set_diag318(cs, arg.host_ulong);
> > > >       }
> > > >   }
> > > > +
> > > > +void s390_cpu_topology_reset(void)
> > > > +{
> > > > +    if (kvm_enabled()) {
> > > > +        kvm_s390_topology_set_mtcr(0);
> > > > +    }
> > > > +}
> > > > diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c
> > > > index f96630440b..9c994d27d5 100644
> > > > --- a/target/s390x/kvm/kvm.c
> > > > +++ b/target/s390x/kvm/kvm.c
> > > > @@ -2585,3 +2585,26 @@ int kvm_s390_get_zpci_op(void)
> > > >   {
> > > >       return cap_zpci_op;
> > > >   }
> > > > +
> > > > +int kvm_s390_topology_set_mtcr(uint64_t attr)
> > > > +{
> > > > +    struct kvm_device_attr attribute = {
> > > > +        .group = KVM_S390_VM_CPU_TOPOLOGY,
> > > > +        .attr  = attr,
> > > > +    };
> > > > +    int ret;
> > > > +
> > > > +    if (!s390_has_feat(S390_FEAT_CONFIGURATION_TOPOLOGY)) {
> > > > +        return -EFAULT;
> > >
> > > EFAULT is something that indicates a bad address (e.g. a segmentation 
> > > fault) ... so this definitely sounds like a bad choice for an error 
> > > code here.
> >
> > Hum, yes, ENODEV seems besser no?
>
> -ENOTSUP would be 'meilleur' may be ?  :)

yes better :)

thanks,
Pierre

--
Pierre Morel
IBM Lab Boeblingen