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 */
virtio_pmem_host_ack(struct virtqueue * vq)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 */
virtio_pmem_flush(struct nd_region * nd_region)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 */
async_pmem_flush(struct nd_region * nd_region,struct bio * bio)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,
109 REQ_OP_WRITE | REQ_PREFLUSH,
110 GFP_ATOMIC);
111
112 if (!child)
113 return -ENOMEM;
114 bio_clone_blkg_association(child, bio);
115 child->bi_iter.bi_sector = -1;
116 bio_chain(child, bio);
117 submit_bio(child);
118 return 0;
119 }
120 if (virtio_pmem_flush(nd_region))
121 return -EIO;
122
123 return 0;
124 };
125 EXPORT_SYMBOL_GPL(async_pmem_flush);
126 MODULE_LICENSE("GPL");
127