KVM: s390: protvirt: do not inject interrupts after start

As PSW restart is handled by the ultravisor (and we only get a start
notification) we must re-check the PSW after a start before injecting
interrupts.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>

arch/s390/kvm/kvm-s390.c

@@ -4515,6 +4515,13 @@ int kvm_s390_vcpu_start(struct kvm_vcpu *vcpu)
 	}
 
 	kvm_s390_clear_cpuflags(vcpu, CPUSTAT_STOPPED);
+	/*
+	 * The real PSW might have changed due to a RESTART interpreted by the
+	 * ultravisor. We block all interrupts and let the next sie exit
+	 * refresh our view.
+	 */
+	if (kvm_s390_pv_cpu_is_protected(vcpu))
+		vcpu->arch.sie_block->gpsw.mask &= ~PSW_INT_MASK;
 	/*
 	 * Another VCPU might have used IBS while we were offline.
 	 * Let's play safe and flush the VCPU at startup.