xref: /openbmc/linux/drivers/nvdimm/nd_virtio.c (revision 799fb82aa132fa3a3886b7872997a5a84e820062)
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");
126