the-tree/block/blk-mq-virtio.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Copyright (c) 2016 Christoph Hellwig.
0004  */
0005 #include <linux/device.h>
0006 #include <linux/blk-mq.h>
0007 #include <linux/blk-mq-virtio.h>
0008 #include <linux/virtio_config.h>
0009 #include <linux/module.h>
0010 #include "blk-mq.h"
0011
0012 /**
0013  * blk_mq_virtio_map_queues - provide a default queue mapping for virtio device
0014  * @qmap:   CPU to hardware queue map.
0015  * @vdev:   virtio device to provide a mapping for.
0016  * @first_vec:  first interrupt vectors to use for queues (usually 0)
0017  *
0018  * This function assumes the virtio device @vdev has at least as many available
0019  * interrupt vectors as @set has queues.  It will then query the vector
0020  * corresponding to each queue for it's affinity mask and built queue mapping
0021  * that maps a queue to the CPUs that have irq affinity for the corresponding
0022  * vector.
0023  */
0024 int blk_mq_virtio_map_queues(struct blk_mq_queue_map *qmap,
0025         struct virtio_device *vdev, int first_vec)
0026 {
0027     const struct cpumask *mask;
0028     unsigned int queue, cpu;
0029
0030     if (!vdev->config->get_vq_affinity)
0031         goto fallback;
0032
0033     for (queue = 0; queue < qmap->nr_queues; queue++) {
0034         mask = vdev->config->get_vq_affinity(vdev, first_vec + queue);
0035         if (!mask)
0036             goto fallback;
0037
0038         for_each_cpu(cpu, mask)
0039             qmap->mq_map[cpu] = qmap->queue_offset + queue;
0040     }
0041
0042     return 0;
0043 fallback:
0044     return blk_mq_map_queues(qmap);
0045 }
0046 EXPORT_SYMBOL_GPL(blk_mq_virtio_map_queues);