KVM: s390: handle stop irqs without action_bits

This patch removes the famous action_bits and moves the handling of
SIGP STOP AND STORE STATUS directly into the SIGP STOP interrupt.

The new local interrupt infrastructure is used to track pending stop
requests.

STOP irqs are the only irqs that don't get actively delivered. They
remain pending until the stop function is executed (=stop intercept).

If another STOP irq is already pending, -EBUSY will now be returned
(needed for the SIGP handling code).

Migration of pending SIGP STOP (AND STORE STATUS) orders should now
be supported out of the box.

Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

1 files changed, 45 insertions, 26 deletions

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 73bafc3d0f41..18721886eb05 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -159,6 +159,12 @@ static unsigned long deliverable_local_irqs(struct kvm_vcpu *vcpu)
 	if (psw_mchk_disabled(vcpu))
 		active_mask &= ~IRQ_PEND_MCHK_MASK;
 
+	/*
+	 * STOP irqs will never be actively delivered. They are triggered via
+	 * intercept requests and cleared when the stop intercept is performed.
+	 */
+	__clear_bit(IRQ_PEND_SIGP_STOP, &active_mask);
+
 	return active_mask;
 }
 
@@ -186,9 +192,6 @@ static void __reset_intercept_indicators(struct kvm_vcpu *vcpu)
 					       LCTL_CR10 | LCTL_CR11);
 		vcpu->arch.sie_block->ictl |= (ICTL_STCTL | ICTL_PINT);
 	}
-
-	if (vcpu->arch.local_int.action_bits & ACTION_STOP_ON_STOP)
-		atomic_set_mask(CPUSTAT_STOP_INT, &vcpu->arch.sie_block->cpuflags);
 }
 
 static void __set_cpuflag(struct kvm_vcpu *vcpu, u32 flag)
@@ -216,11 +219,18 @@ static void set_intercept_indicators_mchk(struct kvm_vcpu *vcpu)
 		vcpu->arch.sie_block->lctl |= LCTL_CR14;
 }
 
+static void set_intercept_indicators_stop(struct kvm_vcpu *vcpu)
+{
+	if (kvm_s390_is_stop_irq_pending(vcpu))
+		__set_cpuflag(vcpu, CPUSTAT_STOP_INT);
+}
+
 /* Set interception request for non-deliverable local interrupts */
 static void set_intercept_indicators_local(struct kvm_vcpu *vcpu)
 {
 	set_intercept_indicators_ext(vcpu);
 	set_intercept_indicators_mchk(vcpu);
+	set_intercept_indicators_stop(vcpu);
 }
 
 static void __set_intercept_indicator(struct kvm_vcpu *vcpu,
@@ -392,25 +402,6 @@ static int __must_check __deliver_restart(struct kvm_vcpu *vcpu)
 	return rc ? -EFAULT : 0;
 }
 
-static int __must_check __deliver_stop(struct kvm_vcpu *vcpu)
-{
-	struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
-	struct kvm_s390_stop_info *stop = &li->irq.stop;
-
-	spin_lock(&li->lock);
-	stop->flags = 0;
-	clear_bit(IRQ_PEND_SIGP_STOP, &li->pending_irqs);
-	spin_unlock(&li->lock);
-
-	VCPU_EVENT(vcpu, 4, "%s", "interrupt: cpu stop");
-	vcpu->stat.deliver_stop_signal++;
-	trace_kvm_s390_deliver_interrupt(vcpu->vcpu_id, KVM_S390_SIGP_STOP,
-					 0, 0);
-
-	__set_cpuflag(vcpu, CPUSTAT_STOP_INT);
-	return 0;
-}
-
 static int __must_check __deliver_set_prefix(struct kvm_vcpu *vcpu)
 {
 	struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
@@ -712,7 +703,6 @@ static const deliver_irq_t deliver_irq_funcs[] = {
 	[IRQ_PEND_EXT_CLOCK_COMP] = __deliver_ckc,
 	[IRQ_PEND_EXT_CPU_TIMER]  = __deliver_cpu_timer,
 	[IRQ_PEND_RESTART]        = __deliver_restart,
-	[IRQ_PEND_SIGP_STOP]      = __deliver_stop,
 	[IRQ_PEND_SET_PREFIX]     = __deliver_set_prefix,
 	[IRQ_PEND_PFAULT_INIT]    = __deliver_pfault_init,
 };
@@ -783,6 +773,9 @@ 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))
+		rc = 1;
+
 	return rc;
 }
 
@@ -1038,20 +1031,29 @@ static int __inject_set_prefix(struct kvm_vcpu *vcpu, struct kvm_s390_irq *irq)
 	return 0;
 }
 
-#define KVM_S390_STOP_SUPP_FLAGS 0
+#define KVM_S390_STOP_SUPP_FLAGS (KVM_S390_STOP_FLAG_STORE_STATUS)
 static int __inject_sigp_stop(struct kvm_vcpu *vcpu, struct kvm_s390_irq *irq)
 {
 	struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
 	struct kvm_s390_stop_info *stop = &li->irq.stop;
+	int rc = 0;
 
 	trace_kvm_s390_inject_vcpu(vcpu->vcpu_id, KVM_S390_SIGP_STOP, 0, 0, 2);
 
 	if (irq->u.stop.flags & ~KVM_S390_STOP_SUPP_FLAGS)
 		return -EINVAL;
 
-	li->action_bits |= ACTION_STOP_ON_STOP;
+	if (is_vcpu_stopped(vcpu)) {
+		if (irq->u.stop.flags & KVM_S390_STOP_FLAG_STORE_STATUS)
+			rc = kvm_s390_store_status_unloaded(vcpu,
+						KVM_S390_STORE_STATUS_NOADDR);
+		return rc;
+	}
+
+	if (test_and_set_bit(IRQ_PEND_SIGP_STOP, &li->pending_irqs))
+		return -EBUSY;
 	stop->flags = irq->u.stop.flags;
-	set_bit(IRQ_PEND_SIGP_STOP, &li->pending_irqs);
+	__set_cpuflag(vcpu, CPUSTAT_STOP_INT);
 	return 0;
 }
 
@@ -1339,6 +1341,23 @@ int s390int_to_s390irq(struct kvm_s390_interrupt *s390int,
 	return 0;
 }
 
+int kvm_s390_is_stop_irq_pending(struct kvm_vcpu *vcpu)
+{
+	struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
+
+	return test_bit(IRQ_PEND_SIGP_STOP, &li->pending_irqs);
+}
+
+void kvm_s390_clear_stop_irq(struct kvm_vcpu *vcpu)
+{
+	struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
+
+	spin_lock(&li->lock);
+	li->irq.stop.flags = 0;
+	clear_bit(IRQ_PEND_SIGP_STOP, &li->pending_irqs);
+	spin_unlock(&li->lock);
+}
+
 int kvm_s390_inject_vcpu(struct kvm_vcpu *vcpu, struct kvm_s390_irq *irq)
 {
 	struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;