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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); | |
8c2e408e | 56 | req_data->req.type = cpu_to_le32(VIRTIO_PMEM_REQ_TYPE_FLUSH); |
6e84200c PG |
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); | |
8c2e408e | 93 | err = le32_to_cpu(req_data->resp.ret); |
6e84200c PG |
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(GFP_ATOMIC, 0); | |
109 | ||
110 | if (!child) | |
111 | return -ENOMEM; | |
112 | bio_copy_dev(child, bio); | |
113 | child->bi_opf = REQ_PREFLUSH; | |
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"); |