Re: [PATCH v3 25/37] KVM: s390: protvirt: Do only reset registers that are accessible

[David Hildenbrand <david@redhat.com>]

On 20.02.20 11:40, Christian Borntraeger wrote:
> From: Janosch Frank <frankja@linux.ibm.com>
> 
> For protected VMs the hypervisor can not access guest breaking event
> address, program parameter, bpbc and todpr. Do not reset those fields
> as the control block does not provide access to these fields.
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> [borntraeger@de.ibm.com: patch merging, splitting, fixing]
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  arch/s390/kvm/kvm-s390.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 436778d3dc14..db28a717a622 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -3478,14 +3478,16 @@ static void kvm_arch_vcpu_ioctl_initial_reset(struct kvm_vcpu *vcpu)
>  	kvm_s390_set_prefix(vcpu, 0);
>  	kvm_s390_set_cpu_timer(vcpu, 0);
>  	vcpu->arch.sie_block->ckc = 0;
> -	vcpu->arch.sie_block->todpr = 0;
>  	memset(vcpu->arch.sie_block->gcr, 0, sizeof(vcpu->arch.sie_block->gcr));
>  	vcpu->arch.sie_block->gcr[0] = CR0_INITIAL_MASK;
>  	vcpu->arch.sie_block->gcr[14] = CR14_INITIAL_MASK;
>  	vcpu->run->s.regs.fpc = 0;
> -	vcpu->arch.sie_block->gbea = 1;
> -	vcpu->arch.sie_block->pp = 0;
> -	vcpu->arch.sie_block->fpf &= ~FPF_BPBC;
> +	if (!kvm_s390_pv_cpu_is_protected(vcpu)) {
> +		vcpu->arch.sie_block->gbea = 1;
> +		vcpu->arch.sie_block->pp = 0;
> +		vcpu->arch.sie_block->fpf &= ~FPF_BPBC;
> +		vcpu->arch.sie_block->todpr = 0;
> +	}
>  }
>  
>  static void kvm_arch_vcpu_ioctl_clear_reset(struct kvm_vcpu *vcpu)
> 

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb