KVM: s390: protvirt: Do only reset registers that are accessible

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>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
[borntraeger@de.ibm.com: patch merging, splitting, fixing]
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

arch/s390/kvm/kvm-s390.c

@@ -3502,14 +3502,21 @@ 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;
+	/*
+	 * Do not reset these registers in the protected case, as some of
+	 * them are overlayed and they are not accessible in this case
+	 * anyway.
+	 */
+	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)