Re: [PATCH v2] KVM: s390: Add new reset vcpu API

Janosch Frank
2019-12-04T10:06:28Z

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On 12/4/19 10:32 AM, Thomas Huth wrote:
> On 03/12/2019 17.20, 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 | 13 +++++++++++++
>> include/uapi/linux/kvm.h | 4 ++++
>> 2 files changed, 17 insertions(+)
>>
>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
>> index d9e6bf3d54f0..602214c5616c 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:
>> @@ -3287,6 +3288,13 @@ static int kvm_arch_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu,
>> return r;
>> }
>>
>> +static int kvm_arch_vcpu_ioctl_normal_reset(struct kvm_vcpu *vcpu)
>> +{
>> + kvm_clear_async_pf_completion_queue(vcpu);
>> + kvm_s390_clear_local_irqs(vcpu);
>> + return 0;
>> +}
>> +
>> static int kvm_arch_vcpu_ioctl_initial_reset(struct kvm_vcpu *vcpu)
>> {
>> kvm_s390_vcpu_initial_reset(vcpu);
>> @@ -4363,7 +4371,12 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
>> r = kvm_arch_vcpu_ioctl_set_initial_psw(vcpu, psw);
>> break;
>> }
>> + case KVM_S390_NORMAL_RESET:
>> + r = kvm_arch_vcpu_ioctl_normal_reset(vcpu);
>> + break;
>> case KVM_S390_INITIAL_RESET:
>> + /* fallthrough */
>> + case KVM_S390_CLEAR_RESET:
>> r = kvm_arch_vcpu_ioctl_initial_reset(vcpu);
>> break;
>
> Isn't clear reset supposed to do more than the initial reset? If so, I'd
> rather expect it the other way round:

In the PV patch I remove the fallthrough and add a function for the
clear reset. I add the UV reset calls into the
kvm_arch_vcpu_ioctl_*_reset() functions, therefore I can't fallthrough
because the Ultravisor does currently not allow staged resets (i.e.
first initial then clear if a clear reset is needed)

>
> case KVM_S390_CLEAR_RESET:
> /* fallthrough */
> case KVM_S390_INITIAL_RESET:
> r = kvm_arch_vcpu_ioctl_initial_reset(vcpu);
> break;
>
> ... so you can later add the additional stuff before the "/* fallthrough
> */"?
>
> Thomas
>

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