Re: [PATCH v10 6/9] s390x/cpu topology: add topology-disable machine property

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

On 10/18/22 19:34, Cédric Le Goater wrote:
> On 10/12/22 18:21, Pierre Morel wrote:
>> S390 CPU topology is only allowed for s390-virtio-ccw-7.3 and
>> newer S390 machines.
>> We keep the possibility to disable the topology on these newer
>> machines with the property topology-disable.
>>
>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>> ---
>>   include/hw/boards.h                |  3 ++
>>   include/hw/s390x/cpu-topology.h    | 18 +++++++++-
>>   include/hw/s390x/s390-virtio-ccw.h |  2 ++
>>   hw/core/machine.c                  |  5 +++
>>   hw/s390x/s390-virtio-ccw.c         | 53 +++++++++++++++++++++++++++++-
>>   util/qemu-config.c                 |  4 +++
>>   qemu-options.hx                    |  6 +++-
>>   7 files changed, 88 insertions(+), 3 deletions(-)
>>
>> diff --git a/include/hw/boards.h b/include/hw/boards.h
>> index 311ed17e18..67147c47bf 100644
>> --- a/include/hw/boards.h
>> +++ b/include/hw/boards.h
>> @@ -379,6 +379,9 @@ struct MachineState {
>>       } \
>>       type_init(machine_initfn##_register_types)
>> +extern GlobalProperty hw_compat_7_2[];
>> +extern const size_t hw_compat_7_2_len;
> 
> QEMU 7.2 is not out yet.

OK, thanks, I will use 7.2 instead of 7.3 as the new machine.
We see later if it goes to 8.0

> 
>> +
>>   extern GlobalProperty hw_compat_7_1[];
>>   extern const size_t hw_compat_7_1_len;
>> diff --git a/include/hw/s390x/cpu-topology.h 
>> b/include/hw/s390x/cpu-topology.h
>> index 35a8a981ec..747c9ab4c6 100644
>> --- a/include/hw/s390x/cpu-topology.h
>> +++ b/include/hw/s390x/cpu-topology.h
>> @@ -12,6 +12,8 @@
>>   #include "hw/qdev-core.h"
>>   #include "qom/object.h"
>> +#include "cpu.h"
>> +#include "hw/s390x/s390-virtio-ccw.h"
>>   #define S390_TOPOLOGY_POLARITY_H  0x00
>> @@ -43,7 +45,21 @@ void s390_topology_new_cpu(int core_id);
>>   static inline bool s390_has_topology(void)
>>   {
>> -    return false;
>> +    static S390CcwMachineState *ccw;
> 
> hmm, s390_has_topology is a static inline. It would be preferable to
> change its definition to extern.

OK

> 
>> +    Object *obj;
>> +
>> +    if (ccw) {
>> +        return !ccw->topology_disable;
>> +    }
>> +
>> +    /* we have to bail out for the "none" machine */
>> +    obj = object_dynamic_cast(qdev_get_machine(),
>> +                              TYPE_S390_CCW_MACHINE);
>> +    if (!obj) {
>> +        return false;
>> +    }
>> +    ccw = S390_CCW_MACHINE(obj);
>> +    return !ccw->topology_disable;
>>   }
>>   #endif
>> diff --git a/include/hw/s390x/s390-virtio-ccw.h 
>> b/include/hw/s390x/s390-virtio-ccw.h
>> index 9e7a0d75bc..6c4b4645fc 100644
>> --- a/include/hw/s390x/s390-virtio-ccw.h
>> +++ b/include/hw/s390x/s390-virtio-ccw.h
>> @@ -28,6 +28,7 @@ struct S390CcwMachineState {
>>       bool dea_key_wrap;
>>       bool pv;
>>       bool zpcii_disable;
>> +    bool topology_disable;
>>       uint8_t loadparm[8];
>>   };
>> @@ -46,6 +47,7 @@ struct S390CcwMachineClass {
>>       bool cpu_model_allowed;
>>       bool css_migration_enabled;
>>       bool hpage_1m_allowed;
>> +    bool topology_allowed;
> 
> 'topology_disable' in the state and 'topology_allowed' in the class.
> This is confusing :/
> 
> you should add 'topology_allowed' in its own patch and maybe call
> it 'topology_capable' ? it is a QEMU capability AIUI

yes, OK, I separate the two.

. topology_capable to know if the QEMU version is capable of handling 
topology

- topology_disable for migration if KVM is not able to handle the 
topology on one of the machines involved.

> 
>>   };
>>   /* runtime-instrumentation allowed by the machine */
>> diff --git a/hw/core/machine.c b/hw/core/machine.c
>> index aa520e74a8..93c497655e 100644
>> --- a/hw/core/machine.c
>> +++ b/hw/core/machine.c
>> @@ -40,6 +40,11 @@
>>   #include "hw/virtio/virtio-pci.h"
>>   #include "qom/object_interfaces.h"
>> +GlobalProperty hw_compat_7_2[] = {
>> +    { "s390-topology", "topology-disable", "true" },
> 
> May be use TYPE_S390_CPU_TOPOLOGY instead.
> 
> But again, this should only apply to 7.1 machines and below. 7.2 is
> not out yet.

OK

> 
> 
>> +};
>> +const size_t hw_compat_7_2_len = G_N_ELEMENTS(hw_compat_7_2);
>> +
>>   GlobalProperty hw_compat_7_1[] = {};
>>   const size_t hw_compat_7_1_len = G_N_ELEMENTS(hw_compat_7_1);
>> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
>> index 362378454a..3a13fad4df 100644
>> --- a/hw/s390x/s390-virtio-ccw.c
>> +++ b/hw/s390x/s390-virtio-ccw.c
>> @@ -616,6 +616,7 @@ static void ccw_machine_class_init(ObjectClass 
>> *oc, void *data)
>>       s390mc->cpu_model_allowed = true;
>>       s390mc->css_migration_enabled = true;
>>       s390mc->hpage_1m_allowed = true;
>> +    s390mc->topology_allowed = true;
>>       mc->init = ccw_init;
>>       mc->reset = s390_machine_reset;
>>       mc->block_default_type = IF_VIRTIO;
>> @@ -726,6 +727,27 @@ bool hpage_1m_allowed(void)
>>       return get_machine_class()->hpage_1m_allowed;
>>   }
>> +static inline bool machine_get_topology_disable(Object *obj, Error 
>> **errp)
>> +{
>> +    S390CcwMachineState *ms = S390_CCW_MACHINE(obj);
>> +
>> +    return ms->topology_disable;
>> +}
>> +
>> +static inline void machine_set_topology_disable(Object *obj, bool value,
>> +                                                Error **errp)
>> +{
>> +    S390CcwMachineState *ms = S390_CCW_MACHINE(obj);
>> +
>> +    if (!get_machine_class()->topology_allowed) {
>> +        error_setg(errp, "Property topology-disable not available on 
>> machine %s",
>> +                   get_machine_class()->parent_class.name);
> 
> OK. I get it now. May be we should consider adding the capability concept
> David introduced in the pseries machine. Please take a look. That's not
> for this patchset though. It would be too much work.

Yes, interesting, would be something to do in the near future.

> 
>> +        return;
>> +    }
>> +
>> +    ms->topology_disable = value;
>> +}
>> +
>>   static char *machine_get_loadparm(Object *obj, Error **errp)
>>   {
>>       S390CcwMachineState *ms = S390_CCW_MACHINE(obj);
>> @@ -784,6 +806,13 @@ static inline void s390_machine_initfn(Object *obj)
>>       object_property_set_description(obj, "zpcii-disable",
>>               "disable zPCI interpretation facilties");
>>       object_property_set_bool(obj, "zpcii-disable", false, NULL);
>> +
>> +    object_property_add_bool(obj, "topology-disable",
>> +                             machine_get_topology_disable,
>> +                             machine_set_topology_disable);
>> +    object_property_set_description(obj, "topology-disable",
>> +            "disable CPU topology");
>> +    object_property_set_bool(obj, "topology-disable", false, NULL);
> 
> All the properties should be added in the machine class_init routine.
> There is a preliminary cleanup patch required to move them all :/

OK, I will move it to the class_init


>>   }
>>   static const TypeInfo ccw_machine_info = {
>> @@ -836,14 +865,36 @@ bool css_migration_enabled(void)
>>       
>> }                                                                         \
>>       type_init(ccw_machine_register_##suffix)
>> +static void ccw_machine_7_3_instance_options(MachineState *machine)
>> +{
>> +}
>> +
>> +static void ccw_machine_7_3_class_options(MachineClass *mc)
>> +{
>> +}
>> +DEFINE_CCW_MACHINE(7_3, "7.3", true);
> 
> That's too early.
> 
>> +
>>   static void ccw_machine_7_2_instance_options(MachineState *machine)
>>   {
>> +    S390CcwMachineState *ms = S390_CCW_MACHINE(machine);
>> +
>> +    ccw_machine_7_3_instance_options(machine);
>> +    ms->topology_disable = true;
>>   }
>>   static void ccw_machine_7_2_class_options(MachineClass *mc)
>>   {
>> +    S390CcwMachineClass *s390mc = S390_CCW_MACHINE_CLASS(mc);
>> +    static GlobalProperty compat[] = {
>> +        { TYPE_S390_CPU_TOPOLOGY, "topology-allowed", "off", },
> 
> hmm, "topology-allowed" is not a TYPE_S390_CPU_TOPOLOGY property.

I do not understand what I did there and why.
I guess I better do nothing there.

Thanks for the comments,

Regards,
Pierre

-- 
Pierre Morel
IBM Lab Boeblingen