virtio-mmio: add error check for platform_get_irq

in vm_find_vqs() irq has a wrong type
so, in case of no IRQ resource defined,
wrong parameter will be passed to request_irq()
Signed-off-by: Ihor Matushchak <ihor.matushchak@foobox.net>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Ivan T. Ivanov <iivanov.xz@gmail.com>

drivers/virtio/virtio_mmio.c

@@ -463,9 +463,14 @@ static int vm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 		       struct irq_affinity *desc)
 {
 	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
-	unsigned int irq = platform_get_irq(vm_dev->pdev, 0);
+	int irq = platform_get_irq(vm_dev->pdev, 0);
 	int i, err, queue_idx = 0;
 
+	if (irq < 0) {
+		dev_err(&vdev->dev, "Cannot get IRQ resource\n");
+		return irq;
+	}
+
 	err = request_irq(irq, vm_interrupt, IRQF_SHARED,
 			dev_name(&vdev->dev), vm_dev);
 	if (err)