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 */ 24 int 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; 43 fallback: 44 return blk_mq_map_queues(qmap); 45 } 46 EXPORT_SYMBOL_GPL(blk_mq_virtio_map_queues); 47