drivers/nvdimm/nd_virtio.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * virtio_pmem.c: Virtio pmem Driver
   4  *
   5  * Discovers persistent memory range information
   6  * from host and provides a virtio based flushing
   7  * interface.
   8  */
   9 #include "virtio_pmem.h"
  10 #include "nd.h"
  11
  12  /* The interrupt handler */
  13 void virtio_pmem_host_ack(struct virtqueue *vq)
  14 {
  15         struct virtio_pmem *vpmem = vq->vdev->priv;
  16         struct virtio_pmem_request *req_data, *req_buf;
  17         unsigned long flags;
  18         unsigned int len;
  19
  20         spin_lock_irqsave(&vpmem->pmem_lock, flags);
  21         while ((req_data = virtqueue_get_buf(vq, &len)) != NULL) {
  22                 req_data->done = true;
  23                 wake_up(&req_data->host_acked);
  24
  25                 if (!list_empty(&vpmem->req_list)) {
  26                         req_buf = list_first_entry(&vpmem->req_list,
  27                                         struct virtio_pmem_request, list);
  28                         req_buf->wq_buf_avail = true;
  29                         wake_up(&req_buf->wq_buf);
  30                         list_del(&req_buf->list);
  31                 }
  32         }
  33         spin_unlock_irqrestore(&vpmem->pmem_lock, flags);
  34 }
  35 EXPORT_SYMBOL_GPL(virtio_pmem_host_ack);
  36
  37  /* The request submission function */
  38 static int virtio_pmem_flush(struct nd_region *nd_region)
  39 {
  40         struct virtio_device *vdev = nd_region->provider_data;
  41         struct virtio_pmem *vpmem  = vdev->priv;
  42         struct virtio_pmem_request *req_data;
  43         struct scatterlist *sgs[2], sg, ret;
  44         unsigned long flags;
  45         int err, err1;
  46
  47         might_sleep();
  48         req_data = kmalloc(sizeof(*req_data), GFP_KERNEL);
  49         if (!req_data)
  50                 return -ENOMEM;
  51
  52         req_data->done = false;
  53         init_waitqueue_head(&req_data->host_acked);
  54         init_waitqueue_head(&req_data->wq_buf);
  55         INIT_LIST_HEAD(&req_data->list);
  56         req_data->req.type = cpu_to_le32(VIRTIO_PMEM_REQ_TYPE_FLUSH);
  57         sg_init_one(&sg, &req_data->req, sizeof(req_data->req));
  58         sgs[0] = &sg;
  59         sg_init_one(&ret, &req_data->resp.ret, sizeof(req_data->resp));
  60         sgs[1] = &ret;
  61
  62         spin_lock_irqsave(&vpmem->pmem_lock, flags);
  63          /*
  64           * If virtqueue_add_sgs returns -ENOSPC then req_vq virtual
  65           * queue does not have free descriptor. We add the request
  66           * to req_list and wait for host_ack to wake us up when free
  67           * slots are available.
  68           */
  69         while ((err = virtqueue_add_sgs(vpmem->req_vq, sgs, 1, 1, req_data,
  70                                         GFP_ATOMIC)) == -ENOSPC) {
  71
  72                 dev_info(&vdev->dev, "failed to send command to virtio pmem device, no free slots in the virtqueue\n");
  73                 req_data->wq_buf_avail = false;
  74                 list_add_tail(&req_data->list, &vpmem->req_list);
  75                 spin_unlock_irqrestore(&vpmem->pmem_lock, flags);
  76
  77                 /* A host response results in "host_ack" getting called */
  78                 wait_event(req_data->wq_buf, req_data->wq_buf_avail);
  79                 spin_lock_irqsave(&vpmem->pmem_lock, flags);
  80         }
  81         err1 = virtqueue_kick(vpmem->req_vq);
  82         spin_unlock_irqrestore(&vpmem->pmem_lock, flags);
  83         /*
  84          * virtqueue_add_sgs failed with error different than -ENOSPC, we can't
  85          * do anything about that.
  86          */
  87         if (err || !err1) {
  88                 dev_info(&vdev->dev, "failed to send command to virtio pmem device\n");
  89                 err = -EIO;
  90         } else {
  91                 /* A host repsonse results in "host_ack" getting called */
  92                 wait_event(req_data->host_acked, req_data->done);
  93                 err = le32_to_cpu(req_data->resp.ret);
  94         }
  95
  96         kfree(req_data);
  97         return err;
  98 };
  99
 100 /* The asynchronous flush callback function */
 101 int async_pmem_flush(struct nd_region *nd_region, struct bio *bio)
 102 {
 103         /*
 104          * Create child bio for asynchronous flush and chain with
 105          * parent bio. Otherwise directly call nd_region flush.
 106          */
 107         if (bio && bio->bi_iter.bi_sector != -1) {
 108                 struct bio *child = bio_alloc(bio->bi_bdev, 0, REQ_PREFLUSH,
 109                                               GFP_ATOMIC);
 110
 111                 if (!child)
 112                         return -ENOMEM;
 113                 bio_clone_blkg_association(child, bio);
 114                 child->bi_iter.bi_sector = -1;
 115                 bio_chain(child, bio);
 116                 submit_bio(child);
 117                 return 0;
 118         }
 119         if (virtio_pmem_flush(nd_region))
 120                 return -EIO;
 121
 122         return 0;
 123 };
 124 EXPORT_SYMBOL_GPL(async_pmem_flush);
 125 MODULE_LICENSE("GPL");