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

Cédric Le Goater
2022-10-27T10:07:37Z

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 ? :)

C.

>
>>
>>   Thomas
>>
>>
>