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

[David Hildenbrand <david@redhat.com>]

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?

-- 
Thanks,

David / dhildenb