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.h>
   8 #include <linux/blk-mq-pci.h>
   9 #include <linux/pci.h>
  10 #include <linux/module.h>
  11
  12 #include "blk-mq.h"
  13
  14 /**
  15  * blk_mq_pci_map_queues - provide a default queue mapping for PCI device
  16  * @qmap:       CPU to hardware queue map.
  17  * @pdev:       PCI device associated with @set.
  18  * @offset:     Offset to use for the pci irq vector
  19  *
  20  * This function assumes the PCI device @pdev has at least as many available
  21  * interrupt vectors as @set has queues.  It will then query the vector
  22  * corresponding to each queue for it's affinity mask and built queue mapping
  23  * that maps a queue to the CPUs that have irq affinity for the corresponding
  24  * vector.
  25  */
  26 int blk_mq_pci_map_queues(struct blk_mq_queue_map *qmap, struct pci_dev *pdev,
  27                             int offset)
  28 {
  29         const struct cpumask *mask;
  30         unsigned int queue, cpu;
  31
  32         for (queue = 0; queue < qmap->nr_queues; queue++) {
  33                 mask = pci_irq_get_affinity(pdev, queue + offset);
  34                 if (!mask)
  35                         goto fallback;
  36
  37                 for_each_cpu(cpu, mask)
  38                         qmap->mq_map[cpu] = qmap->queue_offset + queue;
  39         }
  40
  41         return 0;
  42
  43 fallback:
  44         WARN_ON_ONCE(qmap->nr_queues > 1);
  45         blk_mq_clear_mq_map(qmap);
  46         return 0;
  47 }
  48 EXPORT_SYMBOL_GPL(blk_mq_pci_map_queues);