[PATCH] KVM: arm64: vgic-its: Grab kvm->lock when reading kvm->devices

[Christoffer Dall]

Since we are about to synchronize all accesses to kvm->devices using the
kvm->lock mutex, we should hold this mutex while iterating over the list
of devices in the ITS code.

Also move the vgic_register_its_iodev function to where it's called and
rename it to register_its_iodev to avoid having two almost identially
named functions.

Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
---
 virt/kvm/arm/vgic/vgic-its.c | 64 +++++++++++++++++++++++---------------------
 1 file changed, 34 insertions(+), 30 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index 1cf9f59..4e76877 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -1319,32 +1319,6 @@ void vgic_enable_lpis(struct kvm_vcpu *vcpu)
 		its_sync_lpi_pending_table(vcpu);
 }
 
-static int vgic_register_its_iodev(struct kvm *kvm, struct vgic_its *its)
-{
-	struct vgic_io_device *iodev = &its->iodev;
-	int ret;
-
-	if (!its->initialized)
-		return -EBUSY;
-
-	if (IS_VGIC_ADDR_UNDEF(its->vgic_its_base))
-		return -ENXIO;
-
-	iodev->regions = its_registers;
-	iodev->nr_regions = ARRAY_SIZE(its_registers);
-	kvm_iodevice_init(&iodev->dev, &kvm_io_gic_ops);
-
-	iodev->base_addr = its->vgic_its_base;
-	iodev->iodev_type = IODEV_ITS;
-	iodev->its = its;
-	mutex_lock(&kvm->slots_lock);
-	ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, iodev->base_addr,
-				      KVM_VGIC_V3_ITS_SIZE, &iodev->dev);
-	mutex_unlock(&kvm->slots_lock);
-
-	return ret;
-}
-
 #define INITIAL_BASER_VALUE						  \
 	(GIC_BASER_CACHEABILITY(GITS_BASER, INNER, RaWb)		| \
 	 GIC_BASER_CACHEABILITY(GITS_BASER, OUTER, SameAsInner)		| \
@@ -1526,6 +1500,32 @@ int kvm_vgic_register_its_device(void)
 				       KVM_DEV_TYPE_ARM_VGIC_ITS);
 }
 
+static int register_its_iodev(struct kvm *kvm, struct vgic_its *its)
+{
+	struct vgic_io_device *iodev = &its->iodev;
+	int ret;
+
+	if (!its->initialized)
+		return -EBUSY;
+
+	if (IS_VGIC_ADDR_UNDEF(its->vgic_its_base))
+		return -ENXIO;
+
+	iodev->regions = its_registers;
+	iodev->nr_regions = ARRAY_SIZE(its_registers);
+	kvm_iodevice_init(&iodev->dev, &kvm_io_gic_ops);
+
+	iodev->base_addr = its->vgic_its_base;
+	iodev->iodev_type = IODEV_ITS;
+	iodev->its = its;
+	mutex_lock(&kvm->slots_lock);
+	ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, iodev->base_addr,
+				      KVM_VGIC_V3_ITS_SIZE, &iodev->dev);
+	mutex_unlock(&kvm->slots_lock);
+
+	return ret;
+}
+
 /*
  * Registers all ITSes with the kvm_io_bus framework.
  * To follow the existing VGIC initialization sequence, this has to be
@@ -1536,19 +1536,23 @@ int vgic_register_its_iodevs(struct kvm *kvm)
 	struct kvm_device *dev;
 	int ret = 0;
 
+	mutex_lock(&kvm->lock);
 	list_for_each_entry(dev, &kvm->devices, vm_node) {
 		if (dev->ops != &kvm_arm_vgic_its_ops)
 			continue;
 
-		ret = vgic_register_its_iodev(kvm, dev->private);
+		ret = register_its_iodev(kvm, dev->private);
 		if (ret)
-			return ret;
+			goto out;
+
 		/*
 		 * We don't need to care about tearing down previously
-		 * registered ITSes, as the kvm_io_bus framework removes
-		 * them for us if the VM gets destroyed.
+		 * registered ITSes on error, as the kvm_io_bus framework
+		 * removes them for us if the VM gets destroyed.
 		 */
 	}
 
+out:
+	mutex_unlock(&kvm->lock);
 	return ret;
 }
-- 
2.9.0