Re: [PATCH] KVM: s390: Add new reset vcpu API

[Janosch Frank <frankja@linux.ibm.com>]

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On 11/29/19 3:31 PM, David Hildenbrand wrote:
> On 29.11.19 15:21, Janosch Frank wrote:
>> The architecture states that we need to reset local IRQs for all CPU
>> resets. Because the old reset interface did not support the normal CPU
>> reset we never did that.
>>
>> Now that we have a new interface, let's properly clear out local IRQs
>> and let this commit be a reminder.
>>
>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>> ---
>>  arch/s390/kvm/kvm-s390.c | 25 ++++++++++++++++++++++++-
>>  include/uapi/linux/kvm.h |  7 +++++++
>>  2 files changed, 31 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
>> index d9e6bf3d54f0..2f74ff46b176 100644
>> --- a/arch/s390/kvm/kvm-s390.c
>> +++ b/arch/s390/kvm/kvm-s390.c
>> @@ -529,6 +529,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>>  	case KVM_CAP_S390_CMMA_MIGRATION:
>>  	case KVM_CAP_S390_AIS:
>>  	case KVM_CAP_S390_AIS_MIGRATION:
>> +	case KVM_CAP_S390_VCPU_RESETS:
>>  		r = 1;
>>  		break;
>>  	case KVM_CAP_S390_HPAGE_1M:
>> @@ -3293,6 +3294,25 @@ static int kvm_arch_vcpu_ioctl_initial_reset(struct kvm_vcpu *vcpu)
>>  	return 0;
>>  }
>>  
>> +static int kvm_arch_vcpu_ioctl_reset(struct kvm_vcpu *vcpu, unsigned long type)
>> +{
>> +	int rc = -EINVAL;
>> +
>> +	switch (type) {
>> +	case KVM_S390_VCPU_RESET_NORMAL:
>> +		rc = 0;
>> +		kvm_clear_async_pf_completion_queue(vcpu);
>> +		kvm_s390_clear_local_irqs(vcpu);
>> +		break;
>> +	case KVM_S390_VCPU_RESET_INITIAL:
>> +		/* fallthrough */
>> +	case KVM_S390_VCPU_RESET_CLEAR:
>> +		rc = kvm_arch_vcpu_ioctl_initial_reset(vcpu);
> 
> As we now have two interfaces to achieve the same thing (initial reset),
> I do wonder if we should simply introduce
> 
> KVM_S390_NORMAL_RESET
> KVM_S390_CLEAR_RESET
> 
> instead ...
> 
> Then you can do KVM_S390_NORMAL_RESET for the bugfix and
> KVM_S390_CLEAR_RESET later for PV.
> 
> Does anything speak against that?

Apart from loosing one more ioctl number probably not



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