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

   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 vetors as @set has queues.  It will then queuery 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 */
  24int 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;
  43fallback:
  44        return blk_mq_map_queues(qmap);
  45}
  46EXPORT_SYMBOL_GPL(blk_mq_virtio_map_queues);
  47