1 /* 2 * Copyright (c) 2016 Christoph Hellwig. 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/device.h> 14 #include <linux/blk-mq.h> 15 #include <linux/blk-mq-virtio.h> 16 #include <linux/virtio_config.h> 17 #include <linux/module.h> 18 #include "blk-mq.h" 19 20 /** 21 * blk_mq_virtio_map_queues - provide a default queue mapping for virtio device 22 * @set: tagset to provide the mapping for 23 * @vdev: virtio device associated with @set. 24 * @first_vec: first interrupt vectors to use for queues (usually 0) 25 * 26 * This function assumes the virtio device @vdev has at least as many available 27 * interrupt vetors as @set has queues. It will then queuery the vector 28 * corresponding to each queue for it's affinity mask and built queue mapping 29 * that maps a queue to the CPUs that have irq affinity for the corresponding 30 * vector. 31 */ 32 int blk_mq_virtio_map_queues(struct blk_mq_queue_map *qmap, 33 struct virtio_device *vdev, int first_vec) 34 { 35 const struct cpumask *mask; 36 unsigned int queue, cpu; 37 38 if (!vdev->config->get_vq_affinity) 39 goto fallback; 40 41 for (queue = 0; queue < qmap->nr_queues; queue++) { 42 mask = vdev->config->get_vq_affinity(vdev, first_vec + queue); 43 if (!mask) 44 goto fallback; 45 46 for_each_cpu(cpu, mask) 47 qmap->mq_map[cpu] = qmap->queue_offset + queue; 48 } 49 50 return 0; 51 fallback: 52 return blk_mq_map_queues(qmap); 53 } 54 EXPORT_SYMBOL_GPL(blk_mq_virtio_map_queues); 55