KVM: arm/arm64: Fix spinlock acquisition in vgic_set_owner

vgic_set_owner acquires the irq lock without disabling interrupts, resulting in a lockdep splat (an interrupt could fire and result in the same lock being taken if the same virtual irq is to be injected). In practice, it is almost impossible to trigger this bug, but better safe than sorry. Convert the lock acquisition to a spin_lock_irqsave() and keep lockdep happy. Reported-by: James Morse <[email protected]> Signed-off-by: Marc Zyngier <[email protected]> Signed-off-by: Christoffer Dall <[email protected]>
berg · Dec 1, 2017 · 7465894 · 7465894
1 parent 58d0d19
commit 7465894
Showing 1 changed file with 3 additions and 2 deletions.
diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
@@ -492,6 +492,7 @@ int kvm_vgic_unmap_phys_irq(struct kvm_vcpu *vcpu, unsigned int vintid)
 int kvm_vgic_set_owner(struct kvm_vcpu *vcpu, unsigned int intid, void *owner)
 {
 	struct vgic_irq *irq;
+	unsigned long flags;
 	int ret = 0;
 
 	if (!vgic_initialized(vcpu->kvm))
@@ -502,12 +503,12 @@ int kvm_vgic_set_owner(struct kvm_vcpu *vcpu, unsigned int intid, void *owner)
 		return -EINVAL;
 
 	irq = vgic_get_irq(vcpu->kvm, vcpu, intid);
-	spin_lock(&irq->irq_lock);
+	spin_lock_irqsave(&irq->irq_lock, flags);
 	if (irq->owner && irq->owner != owner)
 		ret = -EEXIST;
 	else
 		irq->owner = owner;
-	spin_unlock(&irq->irq_lock);
+	spin_unlock_irqrestore(&irq->irq_lock, flags);
 
 	return ret;
 }