Re: [RFC PATCH v1 6/6] KVM: s390: Add a routine for setting userspace CPU state

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

On Fri,  8 Oct 2021 22:31:12 +0200
Eric Farman <farman@linux.ibm.com> wrote:

> This capability exists, but we don't record anything when userspace
> enables it. Let's refactor that code so that a note can be made in
> the debug logs that it was enabled.
> 
> Signed-off-by: Eric Farman <farman@linux.ibm.com>

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

> ---
>  arch/s390/kvm/kvm-s390.c | 6 +++---
>  arch/s390/kvm/kvm-s390.h | 9 +++++++++
>  2 files changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 33d71fa42d68..48ac0bd05bee 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -2487,8 +2487,8 @@ long kvm_arch_vm_ioctl(struct file *filp,
>  	case KVM_S390_PV_COMMAND: {
>  		struct kvm_pv_cmd args;
>  
> -		/* protvirt means user sigp */
> -		kvm->arch.user_cpu_state_ctrl = 1;
> +		/* protvirt means user cpu state */
> +		kvm_s390_set_user_cpu_state_ctrl(kvm);
>  		r = 0;
>  		if (!is_prot_virt_host()) {
>  			r = -EINVAL;
> @@ -3801,7 +3801,7 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
>  	vcpu_load(vcpu);
>  
>  	/* user space knows about this interface - let it control the state */
> -	vcpu->kvm->arch.user_cpu_state_ctrl = 1;
> +	kvm_s390_set_user_cpu_state_ctrl(vcpu->kvm);
>  
>  	switch (mp_state->mp_state) {
>  	case KVM_MP_STATE_STOPPED:
> diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
> index 57c5e9369d65..36f4d585513c 100644
> --- a/arch/s390/kvm/kvm-s390.h
> +++ b/arch/s390/kvm/kvm-s390.h
> @@ -208,6 +208,15 @@ static inline int kvm_s390_user_cpu_state_ctrl(struct kvm *kvm)
>  	return kvm->arch.user_cpu_state_ctrl != 0;
>  }
>  
> +static inline void kvm_s390_set_user_cpu_state_ctrl(struct kvm *kvm)
> +{
> +	if (kvm->arch.user_cpu_state_ctrl)
> +		return;
> +
> +	VM_EVENT(kvm, 3, "%s", "ENABLE: Userspace CPU state control");
> +	kvm->arch.user_cpu_state_ctrl = 1;
> +}
> +
>  /* implemented in pv.c */
>  int kvm_s390_pv_destroy_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc);
>  int kvm_s390_pv_create_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc);