1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * Copyright (c) 2017 Sagi Grimberg.
 4 */
 5#include <linux/blk-mq.h>
 6#include <linux/blk-mq-rdma.h>
 7#include <rdma/ib_verbs.h>
 8
 9/**
10 * blk_mq_rdma_map_queues - provide a default queue mapping for rdma device
11 * @map:	CPU to hardware queue map.
12 * @dev:	rdma device to provide a mapping for.
13 * @first_vec:	first interrupt vectors to use for queues (usually 0)
14 *
15 * This function assumes the rdma device @dev has at least as many available
16 * interrupt vetors as @set has queues.  It will then query it's affinity mask
17 * and built queue mapping that maps a queue to the CPUs that have irq affinity
18 * for the corresponding vector.
19 *
20 * In case either the driver passed a @dev with less vectors than
21 * @set->nr_hw_queues, or @dev does not provide an affinity mask for a
22 * vector, we fallback to the naive mapping.
23 */
24void blk_mq_rdma_map_queues(struct blk_mq_queue_map *map,
25		struct ib_device *dev, int first_vec)
26{
27	const struct cpumask *mask;
28	unsigned int queue, cpu;
29
30	for (queue = 0; queue < map->nr_queues; queue++) {
31		mask = ib_get_vector_affinity(dev, first_vec + queue);
32		if (!mask)
33			goto fallback;
34
35		for_each_cpu(cpu, mask)
36			map->mq_map[cpu] = map->queue_offset + queue;
37	}
38
39	return;
40
41fallback:
42	blk_mq_map_queues(map);
43}
44EXPORT_SYMBOL_GPL(blk_mq_rdma_map_queues);