virtio: hookup irq_get_affinity callback

struct bus_type has a new callback for retrieving the IRQ affinity for a
device. Hook this callback up for virtio based devices.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Daniel Wagner <wagi@kernel.org>
Link: https://lore.kernel.org/r/20241202-refactor-blk-affinity-helpers-v6-3-27211e9c2cd5@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/virtio/virtio.c

@@ -377,13 +377,32 @@ static void virtio_dev_remove(struct device *_d)
 	of_node_put(dev->dev.of_node);
 }
 
+/*
+ * virtio_irq_get_affinity - get IRQ affinity mask for device
+ * @_d: ptr to dev structure
+ * @irq_vec: interrupt vector number
+ *
+ * Return the CPU affinity mask for @_d and @irq_vec.
+ */
+static const struct cpumask *virtio_irq_get_affinity(struct device *_d,
+						     unsigned int irq_vec)
+{
+	struct virtio_device *dev = dev_to_virtio(_d);
+
+	if (!dev->config->get_vq_affinity)
+		return NULL;
+
+	return dev->config->get_vq_affinity(dev, irq_vec);
+}
+
 static const struct bus_type virtio_bus = {
 	.name  = "virtio",
 	.match = virtio_dev_match,
 	.dev_groups = virtio_dev_groups,
 	.uevent = virtio_uevent,
 	.probe = virtio_dev_probe,
 	.remove = virtio_dev_remove,
+	.irq_get_affinity = virtio_irq_get_affinity,
 };
 
 int __register_virtio_driver(struct virtio_driver *driver, struct module *owner)