LXR linux/block/blk-mq-virtio.c

   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 */
  32int blk_mq_virtio_map_queues(struct blk_mq_tag_set *set,
  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 < set->nr_hw_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                        set->mq_map[cpu] = queue;
  48        }
  49
  50        return 0;
  51fallback:
  52        return blk_mq_map_queues(set);
  53}
  54EXPORT_SYMBOL_GPL(blk_mq_virtio_map_queues);
  55