diff mbox series

[v11,09/11] s390x/cpu topology: add topology machine property

Message ID 20221103170150.20789-10-pmorel@linux.ibm.com (mailing list archive)
State New, archived
Headers show
Series s390x: CPU Topology | expand

Commit Message

Pierre Morel Nov. 3, 2022, 5:01 p.m. UTC
We keep the possibility to switch on/off the topology on newer
machines with the property topology=[on|off].

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
---
 include/hw/boards.h                |  3 +++
 include/hw/s390x/cpu-topology.h    |  8 +++-----
 include/hw/s390x/s390-virtio-ccw.h |  1 +
 hw/core/machine.c                  |  3 +++
 hw/s390x/cpu-topology.c            | 19 +++++++++++++++++++
 hw/s390x/s390-virtio-ccw.c         | 28 ++++++++++++++++++++++++++++
 util/qemu-config.c                 |  4 ++++
 qemu-options.hx                    |  6 +++++-
 8 files changed, 66 insertions(+), 6 deletions(-)

Comments

Cornelia Huck Nov. 3, 2022, 5:20 p.m. UTC | #1
On Thu, Nov 03 2022, Pierre Morel <pmorel@linux.ibm.com> wrote:

> We keep the possibility to switch on/off the topology on newer
> machines with the property topology=[on|off].
>
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> ---
>  include/hw/boards.h                |  3 +++
>  include/hw/s390x/cpu-topology.h    |  8 +++-----
>  include/hw/s390x/s390-virtio-ccw.h |  1 +
>  hw/core/machine.c                  |  3 +++
>  hw/s390x/cpu-topology.c            | 19 +++++++++++++++++++
>  hw/s390x/s390-virtio-ccw.c         | 28 ++++++++++++++++++++++++++++
>  util/qemu-config.c                 |  4 ++++
>  qemu-options.hx                    |  6 +++++-
>  8 files changed, 66 insertions(+), 6 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;

This still needs to go into a separate patch that introduces the 8.0
machine types for the relevant machines... I'll probably write that
patch soon (next week or so), you can pick it then into this series.

> +
>  extern GlobalProperty hw_compat_7_1[];
>  extern const size_t hw_compat_7_1_len;
>
Pierre Morel Nov. 4, 2022, 10:09 a.m. UTC | #2
On 11/3/22 18:20, Cornelia Huck wrote:
> On Thu, Nov 03 2022, Pierre Morel <pmorel@linux.ibm.com> wrote:
> 
>> We keep the possibility to switch on/off the topology on newer
>> machines with the property topology=[on|off].
>>
>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>> ---
>>   include/hw/boards.h                |  3 +++
>>   include/hw/s390x/cpu-topology.h    |  8 +++-----
>>   include/hw/s390x/s390-virtio-ccw.h |  1 +
>>   hw/core/machine.c                  |  3 +++
>>   hw/s390x/cpu-topology.c            | 19 +++++++++++++++++++
>>   hw/s390x/s390-virtio-ccw.c         | 28 ++++++++++++++++++++++++++++
>>   util/qemu-config.c                 |  4 ++++
>>   qemu-options.hx                    |  6 +++++-
>>   8 files changed, 66 insertions(+), 6 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;
> 
> This still needs to go into a separate patch that introduces the 8.0
> machine types for the relevant machines... I'll probably write that
> patch soon (next week or so), you can pick it then into this series.
> 

Oh sorry, I forgot to suppress these two definitions for this series.
I do not need this for now.
I will probably need your patch introducing the 8.0 for the next spin.

Thanks,
Pierre
Cédric Le Goater Nov. 15, 2022, 1:48 p.m. UTC | #3
On 11/3/22 18:01, Pierre Morel wrote:
> We keep the possibility to switch on/off the topology on newer
> machines with the property topology=[on|off].

The code has changed. You will need to rebase. May be after the
8.0 machine is introduced, or include Cornelia's patch in the
respin.

https://lore.kernel.org/qemu-devel/20221111124534.129111-1-cohuck@redhat.com/

> 
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> ---
>   include/hw/boards.h                |  3 +++
>   include/hw/s390x/cpu-topology.h    |  8 +++-----
>   include/hw/s390x/s390-virtio-ccw.h |  1 +
>   hw/core/machine.c                  |  3 +++
>   hw/s390x/cpu-topology.c            | 19 +++++++++++++++++++
>   hw/s390x/s390-virtio-ccw.c         | 28 ++++++++++++++++++++++++++++
>   util/qemu-config.c                 |  4 ++++
>   qemu-options.hx                    |  6 +++++-
>   8 files changed, 66 insertions(+), 6 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;
> +
>   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 6fec10e032..f566394302 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_CPU_IFL 0x03
>   #define S390_TOPOLOGY_MAX_ORIGIN ((63 + S390_MAX_CPUS) / 64)
> @@ -38,10 +40,6 @@ struct S390Topology {
>   OBJECT_DECLARE_SIMPLE_TYPE(S390Topology, S390_CPU_TOPOLOGY)
>   
>   void s390_topology_new_cpu(S390CPU *cpu);
> -
> -static inline bool s390_has_topology(void)
> -{
> -    return false;
> -}
> +bool s390_has_topology(void);
>   
>   #endif
> diff --git a/include/hw/s390x/s390-virtio-ccw.h b/include/hw/s390x/s390-virtio-ccw.h
> index 89fca3f79f..d7602aedda 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 cpu_topology;
>       uint8_t loadparm[8];
>       void *topology;
>   };
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index aa520e74a8..4f46d4ef23 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -40,6 +40,9 @@
>   #include "hw/virtio/virtio-pci.h"
>   #include "qom/object_interfaces.h"
>   
> +GlobalProperty hw_compat_7_2[] = {};
> +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/cpu-topology.c b/hw/s390x/cpu-topology.c
> index fc220bd8ac..c1550cc1e8 100644
> --- a/hw/s390x/cpu-topology.c
> +++ b/hw/s390x/cpu-topology.c
> @@ -73,6 +73,25 @@ void s390_handle_ptf(S390CPU *cpu, uint8_t r1, uintptr_t ra)
>       }
>   }
>   
> +bool s390_has_topology(void)
> +{
> +    static S390CcwMachineState *ccw;
> +    Object *obj;
> +
> +    if (ccw) {
> +        return ccw->cpu_topology;

Shouldn't we test the capability also ?

	return s390mc->topology_capable && ccw->cpu_topology;

> +    }
> +
> +    /* we have to bail out for the "none" machine */
> +    obj = object_dynamic_cast(qdev_get_machine(),
> +                              TYPE_S390_CCW_MACHINE);
> +    if (!obj) {
> +        return false;
> +    }

Should be an assert I think.

> +    ccw = S390_CCW_MACHINE(obj);
> +    return ccw->cpu_topology;
> +}
> +
>   /*
>    * s390_topology_new_cpu:
>    * @cpu: a pointer to the new CPU
> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
> index f1a9d6e793..ebb5615337 100644
> --- a/hw/s390x/s390-virtio-ccw.c
> +++ b/hw/s390x/s390-virtio-ccw.c
> @@ -710,6 +710,26 @@ bool hpage_1m_allowed(void)
>       return get_machine_class()->hpage_1m_allowed;
>   }
>   
> +static inline bool machine_get_topology(Object *obj, Error **errp)
> +{
> +    S390CcwMachineState *ms = S390_CCW_MACHINE(obj);
> +
> +    return ms->cpu_topology;
> +}
> +
> +static inline void machine_set_topology(Object *obj, bool value, Error **errp)
> +{
> +    S390CcwMachineState *ms = S390_CCW_MACHINE(obj);

You could introduce :

        S390CcwMachineClass *s390mc = S390_CCW_MACHINE_GET_CLASS(ms);


> +
> +    if (!get_machine_class()->topology_capable) {

and
             !s390mc->topology_capable

> +        error_setg(errp, "Property cpu-topology not available on machine %s",
> +                   get_machine_class()->parent_class.name);
> +        return;
> +    }
> +
> +    ms->cpu_topology = value;
> +}
> +
>   static void machine_get_loadparm(Object *obj, Visitor *v,
>                                    const char *name, void *opaque,
>                                    Error **errp)
> @@ -809,6 +829,12 @@ static void ccw_machine_class_init(ObjectClass *oc, void *data)
>                                      machine_set_zpcii_disable);
>       object_class_property_set_description(oc, "zpcii-disable",
>               "disable zPCI interpretation facilties");
> +
> +    object_class_property_add_bool(oc, "topology",
> +                                   machine_get_topology,
> +                                   machine_set_topology);
> +    object_class_property_set_description(oc, "topology",
> +            "enable CPU topology");
>   }
>   
>   static inline void s390_machine_initfn(Object *obj)
> @@ -818,6 +844,7 @@ static inline void s390_machine_initfn(Object *obj)
>       ms->aes_key_wrap = true;
>       ms->dea_key_wrap = true;
>       ms->zpcii_disable = false;
> +    ms->cpu_topology = true;
>   }
>   
>   static const TypeInfo ccw_machine_info = {
> @@ -888,6 +915,7 @@ static void ccw_machine_7_1_instance_options(MachineState *machine)
>       s390_cpudef_featoff_greater(16, 1, S390_FEAT_PAIE);
>       s390_set_qemu_cpu_model(0x8561, 15, 1, qemu_cpu_feat);
>       ms->zpcii_disable = true;
> +    ms->cpu_topology = true;

shouldn't this be false ?


Thanks,

C.

>   }
>   
>   static void ccw_machine_7_1_class_options(MachineClass *mc)
> diff --git a/util/qemu-config.c b/util/qemu-config.c
> index 5325f6bf80..0a040552bd 100644
> --- a/util/qemu-config.c
> +++ b/util/qemu-config.c
> @@ -240,6 +240,10 @@ static QemuOptsList machine_opts = {
>               .name = "zpcii-disable",
>               .type = QEMU_OPT_BOOL,
>               .help = "disable zPCI interpretation facilities",
> +        },{
> +            .name = "topology",
> +            .type = QEMU_OPT_BOOL,
> +            .help = "disable CPU topology",
>           },
>           { /* End of list */ }
>       }
> diff --git a/qemu-options.hx b/qemu-options.hx
> index eb38e5dc40..ef59b28a03 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -38,7 +38,8 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
>       "                hmat=on|off controls ACPI HMAT support (default=off)\n"
>       "                memory-backend='backend-id' specifies explicitly provided backend for main RAM (default=none)\n"
>       "                cxl-fmw.0.targets.0=firsttarget,cxl-fmw.0.targets.1=secondtarget,cxl-fmw.0.size=size[,cxl-fmw.0.interleave-granularity=granularity]\n"
> -    "                zpcii-disable=on|off disables zPCI interpretation facilities (default=off)\n",
> +    "                zpcii-disable=on|off disables zPCI interpretation facilities (default=off)\n"
> +    "                topology=on|off disables CPU topology (default=off)\n",
>       QEMU_ARCH_ALL)
>   SRST
>   ``-machine [type=]name[,prop=value[,...]]``
> @@ -163,6 +164,9 @@ SRST
>           Disables zPCI interpretation facilties on s390-ccw hosts.
>           This feature can be used to disable hardware virtual assists
>           related to zPCI devices. The default is off.
> +
> +    ``topology=on|off``
> +        Disables CPU topology on for S390 machines starting with s390-ccw-virtio-7.3.
>   ERST
>   
>   DEF("M", HAS_ARG, QEMU_OPTION_M,
Pierre Morel Nov. 16, 2022, 12:39 p.m. UTC | #4
On 11/15/22 14:48, Cédric Le Goater wrote:
> On 11/3/22 18:01, Pierre Morel wrote:
>> We keep the possibility to switch on/off the topology on newer
>> machines with the property topology=[on|off].
> 
> The code has changed. You will need to rebase. May be after the
> 8.0 machine is introduced, or include Cornelia's patch in the
> respin.
> 
> https://lore.kernel.org/qemu-devel/20221111124534.129111-1-cohuck@redhat.com/
> 
>>
>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>> ---
>>   include/hw/boards.h                |  3 +++
>>   include/hw/s390x/cpu-topology.h    |  8 +++-----
>>   include/hw/s390x/s390-virtio-ccw.h |  1 +
>>   hw/core/machine.c                  |  3 +++
>>   hw/s390x/cpu-topology.c            | 19 +++++++++++++++++++
>>   hw/s390x/s390-virtio-ccw.c         | 28 ++++++++++++++++++++++++++++
>>   util/qemu-config.c                 |  4 ++++
>>   qemu-options.hx                    |  6 +++++-
>>   8 files changed, 66 insertions(+), 6 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;
>> +
>>   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 6fec10e032..f566394302 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_CPU_IFL 0x03
>>   #define S390_TOPOLOGY_MAX_ORIGIN ((63 + S390_MAX_CPUS) / 64)
>> @@ -38,10 +40,6 @@ struct S390Topology {
>>   OBJECT_DECLARE_SIMPLE_TYPE(S390Topology, S390_CPU_TOPOLOGY)
>>   void s390_topology_new_cpu(S390CPU *cpu);
>> -
>> -static inline bool s390_has_topology(void)
>> -{
>> -    return false;
>> -}
>> +bool s390_has_topology(void);
>>   #endif
>> diff --git a/include/hw/s390x/s390-virtio-ccw.h 
>> b/include/hw/s390x/s390-virtio-ccw.h
>> index 89fca3f79f..d7602aedda 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 cpu_topology;
>>       uint8_t loadparm[8];
>>       void *topology;
>>   };
>> diff --git a/hw/core/machine.c b/hw/core/machine.c
>> index aa520e74a8..4f46d4ef23 100644
>> --- a/hw/core/machine.c
>> +++ b/hw/core/machine.c
>> @@ -40,6 +40,9 @@
>>   #include "hw/virtio/virtio-pci.h"
>>   #include "qom/object_interfaces.h"
>> +GlobalProperty hw_compat_7_2[] = {};
>> +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/cpu-topology.c b/hw/s390x/cpu-topology.c
>> index fc220bd8ac..c1550cc1e8 100644
>> --- a/hw/s390x/cpu-topology.c
>> +++ b/hw/s390x/cpu-topology.c
>> @@ -73,6 +73,25 @@ void s390_handle_ptf(S390CPU *cpu, uint8_t r1, 
>> uintptr_t ra)
>>       }
>>   }
>> +bool s390_has_topology(void)
>> +{
>> +    static S390CcwMachineState *ccw;
>> +    Object *obj;
>> +
>> +    if (ccw) {
>> +        return ccw->cpu_topology;
> 
> Shouldn't we test the capability also ?
> 
>      return s390mc->topology_capable && ccw->cpu_topology;

yes thanks

> 
>> +    }
>> +
>> +    /* we have to bail out for the "none" machine */
>> +    obj = object_dynamic_cast(qdev_get_machine(),
>> +                              TYPE_S390_CCW_MACHINE);
>> +    if (!obj) {
>> +        return false;
>> +    }
> 
> Should be an assert I think.

OK

> 
>> +    ccw = S390_CCW_MACHINE(obj);
>> +    return ccw->cpu_topology;
>> +}
>> +
>>   /*
>>    * s390_topology_new_cpu:
>>    * @cpu: a pointer to the new CPU
>> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
>> index f1a9d6e793..ebb5615337 100644
>> --- a/hw/s390x/s390-virtio-ccw.c
>> +++ b/hw/s390x/s390-virtio-ccw.c
>> @@ -710,6 +710,26 @@ bool hpage_1m_allowed(void)
>>       return get_machine_class()->hpage_1m_allowed;
>>   }
>> +static inline bool machine_get_topology(Object *obj, Error **errp)
>> +{
>> +    S390CcwMachineState *ms = S390_CCW_MACHINE(obj);
>> +
>> +    return ms->cpu_topology;
>> +}
>> +
>> +static inline void machine_set_topology(Object *obj, bool value, 
>> Error **errp)
>> +{
>> +    S390CcwMachineState *ms = S390_CCW_MACHINE(obj);
> 
> You could introduce :
> 
>         S390CcwMachineClass *s390mc = S390_CCW_MACHINE_GET_CLASS(ms);

Yes thanks

> 
> 
>> +
>> +    if (!get_machine_class()->topology_capable) {
> 
> and
>              !s390mc->topology_capable
> 
>> +        error_setg(errp, "Property cpu-topology not available on 
>> machine %s",
>> +                   get_machine_class()->parent_class.name);
>> +        return;
>> +    }
>> +
>> +    ms->cpu_topology = value;
>> +}
>> +
>>   static void machine_get_loadparm(Object *obj, Visitor *v,
>>                                    const char *name, void *opaque,
>>                                    Error **errp)
>> @@ -809,6 +829,12 @@ static void ccw_machine_class_init(ObjectClass 
>> *oc, void *data)
>>                                      machine_set_zpcii_disable);
>>       object_class_property_set_description(oc, "zpcii-disable",
>>               "disable zPCI interpretation facilties");
>> +
>> +    object_class_property_add_bool(oc, "topology",
>> +                                   machine_get_topology,
>> +                                   machine_set_topology);
>> +    object_class_property_set_description(oc, "topology",
>> +            "enable CPU topology");
>>   }
>>   static inline void s390_machine_initfn(Object *obj)
>> @@ -818,6 +844,7 @@ static inline void s390_machine_initfn(Object *obj)
>>       ms->aes_key_wrap = true;
>>       ms->dea_key_wrap = true;
>>       ms->zpcii_disable = false;
>> +    ms->cpu_topology = true;
>>   }
>>   static const TypeInfo ccw_machine_info = {
>> @@ -888,6 +915,7 @@ static void 
>> ccw_machine_7_1_instance_options(MachineState *machine)
>>       s390_cpudef_featoff_greater(16, 1, S390_FEAT_PAIE);
>>       s390_set_qemu_cpu_model(0x8561, 15, 1, qemu_cpu_feat);
>>       ms->zpcii_disable = true;
>> +    ms->cpu_topology = true;
> 
> shouldn't this be false ?

:) yes
I forgot to change this when I change the logic.

Thanks,
Pierre
diff mbox series

Patch

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;
+
 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 6fec10e032..f566394302 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_CPU_IFL 0x03
 #define S390_TOPOLOGY_MAX_ORIGIN ((63 + S390_MAX_CPUS) / 64)
@@ -38,10 +40,6 @@  struct S390Topology {
 OBJECT_DECLARE_SIMPLE_TYPE(S390Topology, S390_CPU_TOPOLOGY)
 
 void s390_topology_new_cpu(S390CPU *cpu);
-
-static inline bool s390_has_topology(void)
-{
-    return false;
-}
+bool s390_has_topology(void);
 
 #endif
diff --git a/include/hw/s390x/s390-virtio-ccw.h b/include/hw/s390x/s390-virtio-ccw.h
index 89fca3f79f..d7602aedda 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 cpu_topology;
     uint8_t loadparm[8];
     void *topology;
 };
diff --git a/hw/core/machine.c b/hw/core/machine.c
index aa520e74a8..4f46d4ef23 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -40,6 +40,9 @@ 
 #include "hw/virtio/virtio-pci.h"
 #include "qom/object_interfaces.h"
 
+GlobalProperty hw_compat_7_2[] = {};
+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/cpu-topology.c b/hw/s390x/cpu-topology.c
index fc220bd8ac..c1550cc1e8 100644
--- a/hw/s390x/cpu-topology.c
+++ b/hw/s390x/cpu-topology.c
@@ -73,6 +73,25 @@  void s390_handle_ptf(S390CPU *cpu, uint8_t r1, uintptr_t ra)
     }
 }
 
+bool s390_has_topology(void)
+{
+    static S390CcwMachineState *ccw;
+    Object *obj;
+
+    if (ccw) {
+        return ccw->cpu_topology;
+    }
+
+    /* 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->cpu_topology;
+}
+
 /*
  * s390_topology_new_cpu:
  * @cpu: a pointer to the new CPU
diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index f1a9d6e793..ebb5615337 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -710,6 +710,26 @@  bool hpage_1m_allowed(void)
     return get_machine_class()->hpage_1m_allowed;
 }
 
+static inline bool machine_get_topology(Object *obj, Error **errp)
+{
+    S390CcwMachineState *ms = S390_CCW_MACHINE(obj);
+
+    return ms->cpu_topology;
+}
+
+static inline void machine_set_topology(Object *obj, bool value, Error **errp)
+{
+    S390CcwMachineState *ms = S390_CCW_MACHINE(obj);
+
+    if (!get_machine_class()->topology_capable) {
+        error_setg(errp, "Property cpu-topology not available on machine %s",
+                   get_machine_class()->parent_class.name);
+        return;
+    }
+
+    ms->cpu_topology = value;
+}
+
 static void machine_get_loadparm(Object *obj, Visitor *v,
                                  const char *name, void *opaque,
                                  Error **errp)
@@ -809,6 +829,12 @@  static void ccw_machine_class_init(ObjectClass *oc, void *data)
                                    machine_set_zpcii_disable);
     object_class_property_set_description(oc, "zpcii-disable",
             "disable zPCI interpretation facilties");
+
+    object_class_property_add_bool(oc, "topology",
+                                   machine_get_topology,
+                                   machine_set_topology);
+    object_class_property_set_description(oc, "topology",
+            "enable CPU topology");
 }
 
 static inline void s390_machine_initfn(Object *obj)
@@ -818,6 +844,7 @@  static inline void s390_machine_initfn(Object *obj)
     ms->aes_key_wrap = true;
     ms->dea_key_wrap = true;
     ms->zpcii_disable = false;
+    ms->cpu_topology = true;
 }
 
 static const TypeInfo ccw_machine_info = {
@@ -888,6 +915,7 @@  static void ccw_machine_7_1_instance_options(MachineState *machine)
     s390_cpudef_featoff_greater(16, 1, S390_FEAT_PAIE);
     s390_set_qemu_cpu_model(0x8561, 15, 1, qemu_cpu_feat);
     ms->zpcii_disable = true;
+    ms->cpu_topology = true;
 }
 
 static void ccw_machine_7_1_class_options(MachineClass *mc)
diff --git a/util/qemu-config.c b/util/qemu-config.c
index 5325f6bf80..0a040552bd 100644
--- a/util/qemu-config.c
+++ b/util/qemu-config.c
@@ -240,6 +240,10 @@  static QemuOptsList machine_opts = {
             .name = "zpcii-disable",
             .type = QEMU_OPT_BOOL,
             .help = "disable zPCI interpretation facilities",
+        },{
+            .name = "topology",
+            .type = QEMU_OPT_BOOL,
+            .help = "disable CPU topology",
         },
         { /* End of list */ }
     }
diff --git a/qemu-options.hx b/qemu-options.hx
index eb38e5dc40..ef59b28a03 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -38,7 +38,8 @@  DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
     "                hmat=on|off controls ACPI HMAT support (default=off)\n"
     "                memory-backend='backend-id' specifies explicitly provided backend for main RAM (default=none)\n"
     "                cxl-fmw.0.targets.0=firsttarget,cxl-fmw.0.targets.1=secondtarget,cxl-fmw.0.size=size[,cxl-fmw.0.interleave-granularity=granularity]\n"
-    "                zpcii-disable=on|off disables zPCI interpretation facilities (default=off)\n",
+    "                zpcii-disable=on|off disables zPCI interpretation facilities (default=off)\n"
+    "                topology=on|off disables CPU topology (default=off)\n",
     QEMU_ARCH_ALL)
 SRST
 ``-machine [type=]name[,prop=value[,...]]``
@@ -163,6 +164,9 @@  SRST
         Disables zPCI interpretation facilties on s390-ccw hosts.
         This feature can be used to disable hardware virtual assists
         related to zPCI devices. The default is off.
+
+    ``topology=on|off``
+        Disables CPU topology on for S390 machines starting with s390-ccw-virtio-7.3.
 ERST
 
 DEF("M", HAS_ARG, QEMU_OPTION_M,