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 */
24 int 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 0;
40
41 fallback:
42 return blk_mq_map_queues(map);
43 }
44 EXPORT_SYMBOL_GPL(blk_mq_rdma_map_queues);