/*
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* Copyright (c) 2016 Christoph Hellwig.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*/
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#include <linux/device.h>
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#include <linux/blk-mq.h>
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#include <linux/blk-mq-virtio.h>
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#include <linux/virtio_config.h>
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#include <linux/module.h>
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#include "blk-mq.h"
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/**
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* blk_mq_virtio_map_queues - provide a default queue mapping for virtio device
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* @set: tagset to provide the mapping for
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* @vdev: virtio device associated with @set.
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* @first_vec: first interrupt vectors to use for queues (usually 0)
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*
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* This function assumes the virtio device @vdev has at least as many available
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* interrupt vetors as @set has queues. It will then queuery the vector
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* corresponding to each queue for it's affinity mask and built queue mapping
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* that maps a queue to the CPUs that have irq affinity for the corresponding
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* vector.
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*/
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int blk_mq_virtio_map_queues(struct blk_mq_tag_set *set,
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struct virtio_device *vdev, int first_vec)
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{
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const struct cpumask *mask;
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unsigned int queue, cpu;
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if (!vdev->config->get_vq_affinity)
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goto fallback;
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for (queue = 0; queue < set->nr_hw_queues; queue++) {
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mask = vdev->config->get_vq_affinity(vdev, first_vec + queue);
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if (!mask)
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goto fallback;
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for_each_cpu(cpu, mask)
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set->mq_map[cpu] = queue;
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}
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return 0;
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fallback:
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return blk_mq_map_queues(set);
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}
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EXPORT_SYMBOL_GPL(blk_mq_virtio_map_queues);
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MODULE_DESCRIPTION("Virtio Device Default Queue Mapping");
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MODULE_LICENSE("GPL v2");
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