1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * Copyright (c) 2016 Christoph Hellwig.
 4 */
 5#include <linux/device.h>
 6#include <linux/blk-mq.h>
 7#include <linux/blk-mq-virtio.h>
 8#include <linux/virtio_config.h>
 9#include <linux/module.h>
10#include "blk-mq.h"
11
12/**
13 * blk_mq_virtio_map_queues - provide a default queue mapping for virtio device
14 * @qmap:	CPU to hardware queue map.
15 * @vdev:	virtio device to provide a mapping for.
16 * @first_vec:	first interrupt vectors to use for queues (usually 0)
17 *
18 * This function assumes the virtio device @vdev has at least as many available
19 * interrupt vectors as @set has queues.  It will then query the vector
20 * corresponding to each queue for it's affinity mask and built queue mapping
21 * that maps a queue to the CPUs that have irq affinity for the corresponding
22 * vector.
23 */
24int blk_mq_virtio_map_queues(struct blk_mq_queue_map *qmap,
25		struct virtio_device *vdev, int first_vec)
26{
27	const struct cpumask *mask;
28	unsigned int queue, cpu;
29
30	if (!vdev->config->get_vq_affinity)
31		goto fallback;
32
33	for (queue = 0; queue < qmap->nr_queues; queue++) {
34		mask = vdev->config->get_vq_affinity(vdev, first_vec + queue);
35		if (!mask)
36			goto fallback;
37
38		for_each_cpu(cpu, mask)
39			qmap->mq_map[cpu] = qmap->queue_offset + queue;
40	}
41
42	return 0;
43fallback:
44	return blk_mq_map_queues(qmap);
45}
46EXPORT_SYMBOL_GPL(blk_mq_virtio_map_queues);