block/blk-mq-pci.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2016 Christoph Hellwig.
   4  */
   5 #include <linux/kobject.h>
   6 #include <linux/blkdev.h>
   7 #include <linux/blk-mq-pci.h>
   8 #include <linux/pci.h>
   9 #include <linux/module.h>
  10
  11 #include "blk-mq.h"
  12
  13 /**
  14  * blk_mq_pci_map_queues - provide a default queue mapping for PCI device
  15  * @qmap:       CPU to hardware queue map.
  16  * @pdev:       PCI device associated with @set.
  17  * @offset:     Offset to use for the pci irq vector
  18  *
  19  * This function assumes the PCI device @pdev has at least as many available
  20  * interrupt vectors as @set has queues.  It will then query the vector
  21  * corresponding to each queue for it's affinity mask and built queue mapping
  22  * that maps a queue to the CPUs that have irq affinity for the corresponding
  23  * vector.
  24  */
  25 void blk_mq_pci_map_queues(struct blk_mq_queue_map *qmap, struct pci_dev *pdev,
  26                            int offset)
  27 {
  28         const struct cpumask *mask;
  29         unsigned int queue, cpu;
  30
  31         for (queue = 0; queue < qmap->nr_queues; queue++) {
  32                 mask = pci_irq_get_affinity(pdev, queue + offset);
  33                 if (!mask)
  34                         goto fallback;
  35
  36                 for_each_cpu(cpu, mask)
  37                         qmap->mq_map[cpu] = qmap->queue_offset + queue;
  38         }
  39
  40         return;
  41
  42 fallback:
  43         WARN_ON_ONCE(qmap->nr_queues > 1);
  44         blk_mq_clear_mq_map(qmap);
  45 }
  46 EXPORT_SYMBOL_GPL(blk_mq_pci_map_queues);