Re: [PATCH v7 8/8] s390x/s390-virtio-ccw: add zpcii-disable machine property

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

On 6/22/22 17:20, Matthew Rosato wrote:
> On 6/22/22 4:50 AM, Pierre Morel wrote:
>>
>>
>> On 6/6/22 22:36, Matthew Rosato wrote:
>>> The zpcii-disable machine property can be used to force-disable the use
>>> of zPCI interpretation facilities for a VM.  By default, this setting
>>> will be off for machine 7.1 and newer.
>>>
>>> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
>>> ---
>>>   hw/s390x/s390-pci-kvm.c            |  4 +++-
>>>   hw/s390x/s390-virtio-ccw.c         | 24 ++++++++++++++++++++++++
>>>   include/hw/s390x/s390-virtio-ccw.h |  1 +
>>>   qemu-options.hx                    |  8 +++++++-
>>>   util/qemu-config.c                 |  4 ++++
>>>   5 files changed, 39 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/hw/s390x/s390-pci-kvm.c b/hw/s390x/s390-pci-kvm.c
>>> index 9134fe185f..5eb7fd12e2 100644
>>> --- a/hw/s390x/s390-pci-kvm.c
>>> +++ b/hw/s390x/s390-pci-kvm.c
>>> @@ -22,7 +22,9 @@
>>>   bool s390_pci_kvm_interp_allowed(void)
>>>   {
>>> -    return kvm_s390_get_zpci_op() && !s390_is_pv();
>>> +    return (kvm_s390_get_zpci_op() && !s390_is_pv() &&
>>> +            !object_property_get_bool(OBJECT(qdev_get_machine()),
>>> +                                      "zpcii-disable", NULL));
>>>   }
>>
>> Isn't it a duplication of machine_get_zpcii_disable?
>>
> 
> No, this will actually trigger machine_get_zpcii_disable -- it was setup 
> as the 'getter' routine in s390_machine_initfn() -- see below:

OK, I did not explain myself correctly:
I was curious why we do not use directly ms->zpci_disabled and use the 
getter.

Does not mean it is false. Far from.

> 
>> Wouldn't it better go to hw/s390x/kvm/ ?
>>
>> There get the MachineState *ms = MACHINE(qdev_get_machine()) and 
>> return the ms->zpcii_disable
>>
>> ?
>>
>>>   int s390_pci_kvm_aif_enable(S390PCIBusDevice *pbdev, ZpciFib *fib, 
>>> bool assist)
>>> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
>>> index cc3097bfee..70229b102b 100644
>>> --- a/hw/s390x/s390-virtio-ccw.c
>>> +++ b/hw/s390x/s390-virtio-ccw.c
>>> @@ -645,6 +645,21 @@ static inline void 
>>> machine_set_dea_key_wrap(Object *obj, bool value,
>>>       ms->dea_key_wrap = value;
>>>   }
>>> +static inline bool machine_get_zpcii_disable(Object *obj, Error **errp)
>>> +{
>>> +    S390CcwMachineState *ms = S390_CCW_MACHINE(obj);
>>> +
>>> +    return ms->zpcii_disable;
>>> +}
>>> +
>>> +static inline void machine_set_zpcii_disable(Object *obj, bool value,
>>> +                                             Error **errp)
>>> +{
>>> +    S390CcwMachineState *ms = S390_CCW_MACHINE(obj);
>>> +
>>> +    ms->zpcii_disable = value;
>>> +}
>>> +
>>>   static S390CcwMachineClass *current_mc;
>>>   /*
>>> @@ -740,6 +755,13 @@ static inline void s390_machine_initfn(Object *obj)
>>>               "Up to 8 chars in set of [A-Za-z0-9. ] (lower case 
>>> chars converted"
>>>               " to upper case) to pass to machine loader, boot manager,"
>>>               " and guest kernel");
>>> +
>>> +    object_property_add_bool(obj, "zpcii-disable",
>>> +                             machine_get_zpcii_disable,
> 
> ^^ Here.

-- 
Pierre Morel
IBM Lab Boeblingen