blk-mq-virtio.c 1.4 KB

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  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. * blk_mq_virtio_map_queues - provide a default queue mapping for virtio device
  13. * @qmap: CPU to hardware queue map.
  14. * @vdev: virtio device to provide a mapping for.
  15. * @first_vec: first interrupt vectors to use for queues (usually 0)
  16. *
  17. * This function assumes the virtio device @vdev has at least as many available
  18. * interrupt vectors as @set has queues. It will then query the vector
  19. * corresponding to each queue for it's affinity mask and built queue mapping
  20. * that maps a queue to the CPUs that have irq affinity for the corresponding
  21. * vector.
  22. */
  23. int blk_mq_virtio_map_queues(struct blk_mq_queue_map *qmap,
  24. struct virtio_device *vdev, int first_vec)
  25. {
  26. const struct cpumask *mask;
  27. unsigned int queue, cpu;
  28. if (!vdev->config->get_vq_affinity)
  29. goto fallback;
  30. for (queue = 0; queue < qmap->nr_queues; queue++) {
  31. mask = vdev->config->get_vq_affinity(vdev, first_vec + queue);
  32. if (!mask)
  33. goto fallback;
  34. for_each_cpu(cpu, mask)
  35. qmap->mq_map[cpu] = qmap->queue_offset + queue;
  36. }
  37. return 0;
  38. fallback:
  39. return blk_mq_map_queues(qmap);
  40. }
  41. EXPORT_SYMBOL_GPL(blk_mq_virtio_map_queues);
  42. MODULE_DESCRIPTION("Virtio Device Default Queue Mapping");
  43. MODULE_LICENSE("GPL v2");