KVM: s390: a VCPU may only stop when no interrupts are left pending

As a SIGP STOP is an interrupt with the least priority, it may only result
in stop of the vcpu when no other interrupts are left pending.

To detect whether a non-stop irq is pending, we need a way to mask out
stop irqs from the general kvm_cpu_has_interrupt() function. For this
reason, the existing function (with an outdated name) is replaced by
kvm_s390_vcpu_has_irq() which allows to mask out pending stop irqs.
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

arch/s390/kvm/intercept.c

@@ -74,6 +74,10 @@ static int handle_stop(struct kvm_vcpu *vcpu)
 
 	vcpu->stat.exit_stop_request++;
 
+	/* delay the stop if any non-stop irq is pending */
+	if (kvm_s390_vcpu_has_irq(vcpu, 1))
+		return 0;
+
 	/* avoid races with the injection/SIGP STOP code */
 	spin_lock(&li->lock);
 	flags = li->irq.stop.flags;

arch/s390/kvm/interrupt.c

@@ -749,7 +749,7 @@ int kvm_s390_si_ext_call_pending(struct kvm_vcpu *vcpu)
 	return 0;
 }
 
-int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu)
+int kvm_s390_vcpu_has_irq(struct kvm_vcpu *vcpu, int exclude_stop)
 {
 	struct kvm_s390_float_interrupt *fi = vcpu->arch.local_int.float_int;
 	struct kvm_s390_interrupt_info  *inti;
@@ -773,7 +773,7 @@ int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu)
 	if (!rc && kvm_s390_si_ext_call_pending(vcpu))
 		rc = 1;
 
-	if (!rc && kvm_s390_is_stop_irq_pending(vcpu))
+	if (!rc && !exclude_stop && kvm_s390_is_stop_irq_pending(vcpu))
 		rc = 1;
 
 	return rc;

arch/s390/kvm/kvm-s390.c

@@ -806,7 +806,7 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm,
 
 int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
 {
-	return kvm_cpu_has_interrupt(vcpu);
+	return kvm_s390_vcpu_has_irq(vcpu, 0);
 }
 
 void s390_vcpu_block(struct kvm_vcpu *vcpu)
@@ -1241,7 +1241,7 @@ static int kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu)
 		return 0;
 	if (psw_extint_disabled(vcpu))
 		return 0;
-	if (kvm_cpu_has_interrupt(vcpu))
+	if (kvm_s390_vcpu_has_irq(vcpu, 0))
 		return 0;
 	if (!(vcpu->arch.sie_block->gcr[0] & 0x200ul))
 		return 0;

arch/s390/kvm/kvm-s390.h

@@ -228,7 +228,7 @@ int s390int_to_s390irq(struct kvm_s390_interrupt *s390int,
 			struct kvm_s390_irq *s390irq);
 
 /* implemented in interrupt.c */
-int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu);
+int kvm_s390_vcpu_has_irq(struct kvm_vcpu *vcpu, int exclude_stop);
 int psw_extint_disabled(struct kvm_vcpu *vcpu);
 void kvm_s390_destroy_adapters(struct kvm *kvm);
 int kvm_s390_si_ext_call_pending(struct kvm_vcpu *vcpu);