1/*
 2 * Copyright (c) 2017 Sagi Grimberg.
 3 *
 4 * This program is free software; you can redistribute it and/or modify it
 5 * under the terms and conditions of the GNU General Public License,
 6 * version 2, as published by the Free Software Foundation.
 7 *
 8 * This program is distributed in the hope it will be useful, but WITHOUT
 9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
11 * more details.
12 */
13#include <linux/blk-mq.h>
14#include <linux/blk-mq-rdma.h>
15#include <rdma/ib_verbs.h>
16
17/**
18 * blk_mq_rdma_map_queues - provide a default queue mapping for rdma device
19 * @set:	tagset to provide the mapping for
20 * @dev:	rdma device associated with @set.
21 * @first_vec:	first interrupt vectors to use for queues (usually 0)
22 *
23 * This function assumes the rdma device @dev has at least as many available
24 * interrupt vetors as @set has queues.  It will then query it's affinity mask
25 * and built queue mapping that maps a queue to the CPUs that have irq affinity
26 * for the corresponding vector.
27 *
28 * In case either the driver passed a @dev with less vectors than
29 * @set->nr_hw_queues, or @dev does not provide an affinity mask for a
30 * vector, we fallback to the naive mapping.
31 */
32int blk_mq_rdma_map_queues(struct blk_mq_tag_set *set,
33		struct ib_device *dev, int first_vec)
34{
35	const struct cpumask *mask;
36	unsigned int queue, cpu;
37
38	for (queue = 0; queue < set->nr_hw_queues; queue++) {
39		mask = ib_get_vector_affinity(dev, first_vec + queue);
40		if (!mask)
41			goto fallback;
42
43		for_each_cpu(cpu, mask)
44			set->mq_map[cpu] = queue;
45	}
46
47	return 0;
48
49fallback:
50	return blk_mq_map_queues(set);
51}
52EXPORT_SYMBOL_GPL(blk_mq_rdma_map_queues);