1 // SPDX-License-Identifier: GPL-2.0-only
2 //#define DEBUG
3 #include <linux/spinlock.h>
4 #include <linux/slab.h>
5 #include <linux/blkdev.h>
6 #include <linux/hdreg.h>
7 #include <linux/module.h>
8 #include <linux/mutex.h>
9 #include <linux/interrupt.h>
10 #include <linux/virtio.h>
11 #include <linux/virtio_blk.h>
12 #include <linux/scatterlist.h>
13 #include <linux/string_helpers.h>
14 #include <linux/idr.h>
15 #include <linux/blk-mq.h>
16 #include <linux/blk-mq-virtio.h>
17 #include <linux/numa.h>
18 #include <uapi/linux/virtio_ring.h>
19
20 #define PART_BITS 4
21 #define VQ_NAME_LEN 16
22 #define MAX_DISCARD_SEGMENTS 256u
23
24 static int major;
25 static DEFINE_IDA(vd_index_ida);
26
27 static struct workqueue_struct *virtblk_wq;
28
29 struct virtio_blk_vq {
30 struct virtqueue *vq;
31 spinlock_t lock;
32 char name[VQ_NAME_LEN];
33 } ____cacheline_aligned_in_smp;
34
35 struct virtio_blk {
36 /*
37 * This mutex must be held by anything that may run after
38 * virtblk_remove() sets vblk->vdev to NULL.
39 *
40 * blk-mq, virtqueue processing, and sysfs attribute code paths are
41 * shut down before vblk->vdev is set to NULL and therefore do not need
42 * to hold this mutex.
43 */
44 struct mutex vdev_mutex;
45 struct virtio_device *vdev;
46
47 /* The disk structure for the kernel. */
48 struct gendisk *disk;
49
50 /* Block layer tags. */
51 struct blk_mq_tag_set tag_set;
52
53 /* Process context for config space updates */
54 struct work_struct config_work;
55
56 /*
57 * Tracks references from block_device_operations open/release and
58 * virtio_driver probe/remove so this object can be freed once no
59 * longer in use.
60 */
61 refcount_t refs;
62
63 /* What host tells us, plus 2 for header & tailer. */
64 unsigned int sg_elems;
65
66 /* Ida index - used to track minor number allocations. */
67 int index;
68
69 /* num of vqs */
70 int num_vqs;
71 struct virtio_blk_vq *vqs;
72 };
73
74 struct virtblk_req {
75 struct virtio_blk_outhdr out_hdr;
76 u8 status;
77 struct scatterlist sg[];
78 };
79
virtblk_result(struct virtblk_req * vbr)80 static inline blk_status_t virtblk_result(struct virtblk_req *vbr)
81 {
82 switch (vbr->status) {
83 case VIRTIO_BLK_S_OK:
84 return BLK_STS_OK;
85 case VIRTIO_BLK_S_UNSUPP:
86 return BLK_STS_NOTSUPP;
87 default:
88 return BLK_STS_IOERR;
89 }
90 }
91
virtblk_add_req(struct virtqueue * vq,struct virtblk_req * vbr,struct scatterlist * data_sg,bool have_data)92 static int virtblk_add_req(struct virtqueue *vq, struct virtblk_req *vbr,
93 struct scatterlist *data_sg, bool have_data)
94 {
95 struct scatterlist hdr, status, *sgs[3];
96 unsigned int num_out = 0, num_in = 0;
97
98 sg_init_one(&hdr, &vbr->out_hdr, sizeof(vbr->out_hdr));
99 sgs[num_out++] = &hdr;
100
101 if (have_data) {
102 if (vbr->out_hdr.type & cpu_to_virtio32(vq->vdev, VIRTIO_BLK_T_OUT))
103 sgs[num_out++] = data_sg;
104 else
105 sgs[num_out + num_in++] = data_sg;
106 }
107
108 sg_init_one(&status, &vbr->status, sizeof(vbr->status));
109 sgs[num_out + num_in++] = &status;
110
111 return virtqueue_add_sgs(vq, sgs, num_out, num_in, vbr, GFP_ATOMIC);
112 }
113
virtblk_setup_discard_write_zeroes(struct request * req,bool unmap)114 static int virtblk_setup_discard_write_zeroes(struct request *req, bool unmap)
115 {
116 unsigned short segments = blk_rq_nr_discard_segments(req);
117 unsigned short n = 0;
118 struct virtio_blk_discard_write_zeroes *range;
119 struct bio *bio;
120 u32 flags = 0;
121
122 if (unmap)
123 flags |= VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP;
124
125 range = kmalloc_array(segments, sizeof(*range), GFP_ATOMIC);
126 if (!range)
127 return -ENOMEM;
128
129 /*
130 * Single max discard segment means multi-range discard isn't
131 * supported, and block layer only runs contiguity merge like
132 * normal RW request. So we can't reply on bio for retrieving
133 * each range info.
134 */
135 if (queue_max_discard_segments(req->q) == 1) {
136 range[0].flags = cpu_to_le32(flags);
137 range[0].num_sectors = cpu_to_le32(blk_rq_sectors(req));
138 range[0].sector = cpu_to_le64(blk_rq_pos(req));
139 n = 1;
140 } else {
141 __rq_for_each_bio(bio, req) {
142 u64 sector = bio->bi_iter.bi_sector;
143 u32 num_sectors = bio->bi_iter.bi_size >> SECTOR_SHIFT;
144
145 range[n].flags = cpu_to_le32(flags);
146 range[n].num_sectors = cpu_to_le32(num_sectors);
147 range[n].sector = cpu_to_le64(sector);
148 n++;
149 }
150 }
151
152 WARN_ON_ONCE(n != segments);
153
154 req->special_vec.bv_page = virt_to_page(range);
155 req->special_vec.bv_offset = offset_in_page(range);
156 req->special_vec.bv_len = sizeof(*range) * segments;
157 req->rq_flags |= RQF_SPECIAL_PAYLOAD;
158
159 return 0;
160 }
161
virtblk_request_done(struct request * req)162 static inline void virtblk_request_done(struct request *req)
163 {
164 struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
165
166 if (req->rq_flags & RQF_SPECIAL_PAYLOAD) {
167 kfree(page_address(req->special_vec.bv_page) +
168 req->special_vec.bv_offset);
169 }
170
171 blk_mq_end_request(req, virtblk_result(vbr));
172 }
173
virtblk_done(struct virtqueue * vq)174 static void virtblk_done(struct virtqueue *vq)
175 {
176 struct virtio_blk *vblk = vq->vdev->priv;
177 bool req_done = false;
178 int qid = vq->index;
179 struct virtblk_req *vbr;
180 unsigned long flags;
181 unsigned int len;
182
183 spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
184 do {
185 virtqueue_disable_cb(vq);
186 while ((vbr = virtqueue_get_buf(vblk->vqs[qid].vq, &len)) != NULL) {
187 struct request *req = blk_mq_rq_from_pdu(vbr);
188
189 if (likely(!blk_should_fake_timeout(req->q)))
190 blk_mq_complete_request(req);
191 req_done = true;
192 }
193 if (unlikely(virtqueue_is_broken(vq)))
194 break;
195 } while (!virtqueue_enable_cb(vq));
196
197 /* In case queue is stopped waiting for more buffers. */
198 if (req_done)
199 blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
200 spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
201 }
202
virtio_commit_rqs(struct blk_mq_hw_ctx * hctx)203 static void virtio_commit_rqs(struct blk_mq_hw_ctx *hctx)
204 {
205 struct virtio_blk *vblk = hctx->queue->queuedata;
206 struct virtio_blk_vq *vq = &vblk->vqs[hctx->queue_num];
207 bool kick;
208
209 spin_lock_irq(&vq->lock);
210 kick = virtqueue_kick_prepare(vq->vq);
211 spin_unlock_irq(&vq->lock);
212
213 if (kick)
214 virtqueue_notify(vq->vq);
215 }
216
virtio_queue_rq(struct blk_mq_hw_ctx * hctx,const struct blk_mq_queue_data * bd)217 static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
218 const struct blk_mq_queue_data *bd)
219 {
220 struct virtio_blk *vblk = hctx->queue->queuedata;
221 struct request *req = bd->rq;
222 struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
223 unsigned long flags;
224 unsigned int num;
225 int qid = hctx->queue_num;
226 int err;
227 bool notify = false;
228 bool unmap = false;
229 u32 type;
230
231 BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
232
233 switch (req_op(req)) {
234 case REQ_OP_READ:
235 case REQ_OP_WRITE:
236 type = 0;
237 break;
238 case REQ_OP_FLUSH:
239 type = VIRTIO_BLK_T_FLUSH;
240 break;
241 case REQ_OP_DISCARD:
242 type = VIRTIO_BLK_T_DISCARD;
243 break;
244 case REQ_OP_WRITE_ZEROES:
245 type = VIRTIO_BLK_T_WRITE_ZEROES;
246 unmap = !(req->cmd_flags & REQ_NOUNMAP);
247 break;
248 case REQ_OP_DRV_IN:
249 type = VIRTIO_BLK_T_GET_ID;
250 break;
251 default:
252 WARN_ON_ONCE(1);
253 return BLK_STS_IOERR;
254 }
255
256 vbr->out_hdr.type = cpu_to_virtio32(vblk->vdev, type);
257 vbr->out_hdr.sector = type ?
258 0 : cpu_to_virtio64(vblk->vdev, blk_rq_pos(req));
259 vbr->out_hdr.ioprio = cpu_to_virtio32(vblk->vdev, req_get_ioprio(req));
260
261 blk_mq_start_request(req);
262
263 if (type == VIRTIO_BLK_T_DISCARD || type == VIRTIO_BLK_T_WRITE_ZEROES) {
264 err = virtblk_setup_discard_write_zeroes(req, unmap);
265 if (err)
266 return BLK_STS_RESOURCE;
267 }
268
269 num = blk_rq_map_sg(hctx->queue, req, vbr->sg);
270 if (num) {
271 if (rq_data_dir(req) == WRITE)
272 vbr->out_hdr.type |= cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_OUT);
273 else
274 vbr->out_hdr.type |= cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_IN);
275 }
276
277 spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
278 err = virtblk_add_req(vblk->vqs[qid].vq, vbr, vbr->sg, num);
279 if (err) {
280 virtqueue_kick(vblk->vqs[qid].vq);
281 /* Don't stop the queue if -ENOMEM: we may have failed to
282 * bounce the buffer due to global resource outage.
283 */
284 if (err == -ENOSPC)
285 blk_mq_stop_hw_queue(hctx);
286 spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
287 switch (err) {
288 case -ENOSPC:
289 return BLK_STS_DEV_RESOURCE;
290 case -ENOMEM:
291 return BLK_STS_RESOURCE;
292 default:
293 return BLK_STS_IOERR;
294 }
295 }
296
297 if (bd->last && virtqueue_kick_prepare(vblk->vqs[qid].vq))
298 notify = true;
299 spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
300
301 if (notify)
302 virtqueue_notify(vblk->vqs[qid].vq);
303 return BLK_STS_OK;
304 }
305
306 /* return id (s/n) string for *disk to *id_str
307 */
virtblk_get_id(struct gendisk * disk,char * id_str)308 static int virtblk_get_id(struct gendisk *disk, char *id_str)
309 {
310 struct virtio_blk *vblk = disk->private_data;
311 struct request_queue *q = vblk->disk->queue;
312 struct request *req;
313 int err;
314
315 req = blk_get_request(q, REQ_OP_DRV_IN, 0);
316 if (IS_ERR(req))
317 return PTR_ERR(req);
318
319 err = blk_rq_map_kern(q, req, id_str, VIRTIO_BLK_ID_BYTES, GFP_KERNEL);
320 if (err)
321 goto out;
322
323 blk_execute_rq(vblk->disk->queue, vblk->disk, req, false);
324 err = blk_status_to_errno(virtblk_result(blk_mq_rq_to_pdu(req)));
325 out:
326 blk_put_request(req);
327 return err;
328 }
329
virtblk_get(struct virtio_blk * vblk)330 static void virtblk_get(struct virtio_blk *vblk)
331 {
332 refcount_inc(&vblk->refs);
333 }
334
virtblk_put(struct virtio_blk * vblk)335 static void virtblk_put(struct virtio_blk *vblk)
336 {
337 if (refcount_dec_and_test(&vblk->refs)) {
338 ida_simple_remove(&vd_index_ida, vblk->index);
339 mutex_destroy(&vblk->vdev_mutex);
340 kfree(vblk);
341 }
342 }
343
virtblk_open(struct block_device * bd,fmode_t mode)344 static int virtblk_open(struct block_device *bd, fmode_t mode)
345 {
346 struct virtio_blk *vblk = bd->bd_disk->private_data;
347 int ret = 0;
348
349 mutex_lock(&vblk->vdev_mutex);
350
351 if (vblk->vdev)
352 virtblk_get(vblk);
353 else
354 ret = -ENXIO;
355
356 mutex_unlock(&vblk->vdev_mutex);
357 return ret;
358 }
359
virtblk_release(struct gendisk * disk,fmode_t mode)360 static void virtblk_release(struct gendisk *disk, fmode_t mode)
361 {
362 struct virtio_blk *vblk = disk->private_data;
363
364 virtblk_put(vblk);
365 }
366
367 /* We provide getgeo only to please some old bootloader/partitioning tools */
virtblk_getgeo(struct block_device * bd,struct hd_geometry * geo)368 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
369 {
370 struct virtio_blk *vblk = bd->bd_disk->private_data;
371 int ret = 0;
372
373 mutex_lock(&vblk->vdev_mutex);
374
375 if (!vblk->vdev) {
376 ret = -ENXIO;
377 goto out;
378 }
379
380 /* see if the host passed in geometry config */
381 if (virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_GEOMETRY)) {
382 virtio_cread(vblk->vdev, struct virtio_blk_config,
383 geometry.cylinders, &geo->cylinders);
384 virtio_cread(vblk->vdev, struct virtio_blk_config,
385 geometry.heads, &geo->heads);
386 virtio_cread(vblk->vdev, struct virtio_blk_config,
387 geometry.sectors, &geo->sectors);
388 } else {
389 /* some standard values, similar to sd */
390 geo->heads = 1 << 6;
391 geo->sectors = 1 << 5;
392 geo->cylinders = get_capacity(bd->bd_disk) >> 11;
393 }
394 out:
395 mutex_unlock(&vblk->vdev_mutex);
396 return ret;
397 }
398
399 static const struct block_device_operations virtblk_fops = {
400 .owner = THIS_MODULE,
401 .open = virtblk_open,
402 .release = virtblk_release,
403 .getgeo = virtblk_getgeo,
404 };
405
index_to_minor(int index)406 static int index_to_minor(int index)
407 {
408 return index << PART_BITS;
409 }
410
minor_to_index(int minor)411 static int minor_to_index(int minor)
412 {
413 return minor >> PART_BITS;
414 }
415
serial_show(struct device * dev,struct device_attribute * attr,char * buf)416 static ssize_t serial_show(struct device *dev,
417 struct device_attribute *attr, char *buf)
418 {
419 struct gendisk *disk = dev_to_disk(dev);
420 int err;
421
422 /* sysfs gives us a PAGE_SIZE buffer */
423 BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);
424
425 buf[VIRTIO_BLK_ID_BYTES] = '\0';
426 err = virtblk_get_id(disk, buf);
427 if (!err)
428 return strlen(buf);
429
430 if (err == -EIO) /* Unsupported? Make it empty. */
431 return 0;
432
433 return err;
434 }
435
436 static DEVICE_ATTR_RO(serial);
437
438 /* The queue's logical block size must be set before calling this */
virtblk_update_capacity(struct virtio_blk * vblk,bool resize)439 static void virtblk_update_capacity(struct virtio_blk *vblk, bool resize)
440 {
441 struct virtio_device *vdev = vblk->vdev;
442 struct request_queue *q = vblk->disk->queue;
443 char cap_str_2[10], cap_str_10[10];
444 unsigned long long nblocks;
445 u64 capacity;
446
447 /* Host must always specify the capacity. */
448 virtio_cread(vdev, struct virtio_blk_config, capacity, &capacity);
449
450 /* If capacity is too big, truncate with warning. */
451 if ((sector_t)capacity != capacity) {
452 dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
453 (unsigned long long)capacity);
454 capacity = (sector_t)-1;
455 }
456
457 nblocks = DIV_ROUND_UP_ULL(capacity, queue_logical_block_size(q) >> 9);
458
459 string_get_size(nblocks, queue_logical_block_size(q),
460 STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));
461 string_get_size(nblocks, queue_logical_block_size(q),
462 STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));
463
464 dev_notice(&vdev->dev,
465 "[%s] %s%llu %d-byte logical blocks (%s/%s)\n",
466 vblk->disk->disk_name,
467 resize ? "new size: " : "",
468 nblocks,
469 queue_logical_block_size(q),
470 cap_str_10,
471 cap_str_2);
472
473 set_capacity_revalidate_and_notify(vblk->disk, capacity, true);
474 }
475
virtblk_config_changed_work(struct work_struct * work)476 static void virtblk_config_changed_work(struct work_struct *work)
477 {
478 struct virtio_blk *vblk =
479 container_of(work, struct virtio_blk, config_work);
480
481 virtblk_update_capacity(vblk, true);
482 }
483
virtblk_config_changed(struct virtio_device * vdev)484 static void virtblk_config_changed(struct virtio_device *vdev)
485 {
486 struct virtio_blk *vblk = vdev->priv;
487
488 queue_work(virtblk_wq, &vblk->config_work);
489 }
490
init_vq(struct virtio_blk * vblk)491 static int init_vq(struct virtio_blk *vblk)
492 {
493 int err;
494 int i;
495 vq_callback_t **callbacks;
496 const char **names;
497 struct virtqueue **vqs;
498 unsigned short num_vqs;
499 struct virtio_device *vdev = vblk->vdev;
500 struct irq_affinity desc = { 0, };
501
502 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_MQ,
503 struct virtio_blk_config, num_queues,
504 &num_vqs);
505 if (err)
506 num_vqs = 1;
507
508 num_vqs = min_t(unsigned int, nr_cpu_ids, num_vqs);
509
510 vblk->vqs = kmalloc_array(num_vqs, sizeof(*vblk->vqs), GFP_KERNEL);
511 if (!vblk->vqs)
512 return -ENOMEM;
513
514 names = kmalloc_array(num_vqs, sizeof(*names), GFP_KERNEL);
515 callbacks = kmalloc_array(num_vqs, sizeof(*callbacks), GFP_KERNEL);
516 vqs = kmalloc_array(num_vqs, sizeof(*vqs), GFP_KERNEL);
517 if (!names || !callbacks || !vqs) {
518 err = -ENOMEM;
519 goto out;
520 }
521
522 for (i = 0; i < num_vqs; i++) {
523 callbacks[i] = virtblk_done;
524 snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req.%d", i);
525 names[i] = vblk->vqs[i].name;
526 }
527
528 /* Discover virtqueues and write information to configuration. */
529 err = virtio_find_vqs(vdev, num_vqs, vqs, callbacks, names, &desc);
530 if (err)
531 goto out;
532
533 for (i = 0; i < num_vqs; i++) {
534 spin_lock_init(&vblk->vqs[i].lock);
535 vblk->vqs[i].vq = vqs[i];
536 }
537 vblk->num_vqs = num_vqs;
538
539 out:
540 kfree(vqs);
541 kfree(callbacks);
542 kfree(names);
543 if (err)
544 kfree(vblk->vqs);
545 return err;
546 }
547
548 /*
549 * Legacy naming scheme used for virtio devices. We are stuck with it for
550 * virtio blk but don't ever use it for any new driver.
551 */
virtblk_name_format(char * prefix,int index,char * buf,int buflen)552 static int virtblk_name_format(char *prefix, int index, char *buf, int buflen)
553 {
554 const int base = 'z' - 'a' + 1;
555 char *begin = buf + strlen(prefix);
556 char *end = buf + buflen;
557 char *p;
558 int unit;
559
560 p = end - 1;
561 *p = '\0';
562 unit = base;
563 do {
564 if (p == begin)
565 return -EINVAL;
566 *--p = 'a' + (index % unit);
567 index = (index / unit) - 1;
568 } while (index >= 0);
569
570 memmove(begin, p, end - p);
571 memcpy(buf, prefix, strlen(prefix));
572
573 return 0;
574 }
575
virtblk_get_cache_mode(struct virtio_device * vdev)576 static int virtblk_get_cache_mode(struct virtio_device *vdev)
577 {
578 u8 writeback;
579 int err;
580
581 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE,
582 struct virtio_blk_config, wce,
583 &writeback);
584
585 /*
586 * If WCE is not configurable and flush is not available,
587 * assume no writeback cache is in use.
588 */
589 if (err)
590 writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH);
591
592 return writeback;
593 }
594
virtblk_update_cache_mode(struct virtio_device * vdev)595 static void virtblk_update_cache_mode(struct virtio_device *vdev)
596 {
597 u8 writeback = virtblk_get_cache_mode(vdev);
598 struct virtio_blk *vblk = vdev->priv;
599
600 blk_queue_write_cache(vblk->disk->queue, writeback, false);
601 revalidate_disk_size(vblk->disk, true);
602 }
603
604 static const char *const virtblk_cache_types[] = {
605 "write through", "write back"
606 };
607
608 static ssize_t
cache_type_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)609 cache_type_store(struct device *dev, struct device_attribute *attr,
610 const char *buf, size_t count)
611 {
612 struct gendisk *disk = dev_to_disk(dev);
613 struct virtio_blk *vblk = disk->private_data;
614 struct virtio_device *vdev = vblk->vdev;
615 int i;
616
617 BUG_ON(!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_CONFIG_WCE));
618 i = sysfs_match_string(virtblk_cache_types, buf);
619 if (i < 0)
620 return i;
621
622 virtio_cwrite8(vdev, offsetof(struct virtio_blk_config, wce), i);
623 virtblk_update_cache_mode(vdev);
624 return count;
625 }
626
627 static ssize_t
cache_type_show(struct device * dev,struct device_attribute * attr,char * buf)628 cache_type_show(struct device *dev, struct device_attribute *attr, char *buf)
629 {
630 struct gendisk *disk = dev_to_disk(dev);
631 struct virtio_blk *vblk = disk->private_data;
632 u8 writeback = virtblk_get_cache_mode(vblk->vdev);
633
634 BUG_ON(writeback >= ARRAY_SIZE(virtblk_cache_types));
635 return snprintf(buf, 40, "%s\n", virtblk_cache_types[writeback]);
636 }
637
638 static DEVICE_ATTR_RW(cache_type);
639
640 static struct attribute *virtblk_attrs[] = {
641 &dev_attr_serial.attr,
642 &dev_attr_cache_type.attr,
643 NULL,
644 };
645
virtblk_attrs_are_visible(struct kobject * kobj,struct attribute * a,int n)646 static umode_t virtblk_attrs_are_visible(struct kobject *kobj,
647 struct attribute *a, int n)
648 {
649 struct device *dev = kobj_to_dev(kobj);
650 struct gendisk *disk = dev_to_disk(dev);
651 struct virtio_blk *vblk = disk->private_data;
652 struct virtio_device *vdev = vblk->vdev;
653
654 if (a == &dev_attr_cache_type.attr &&
655 !virtio_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE))
656 return S_IRUGO;
657
658 return a->mode;
659 }
660
661 static const struct attribute_group virtblk_attr_group = {
662 .attrs = virtblk_attrs,
663 .is_visible = virtblk_attrs_are_visible,
664 };
665
666 static const struct attribute_group *virtblk_attr_groups[] = {
667 &virtblk_attr_group,
668 NULL,
669 };
670
virtblk_init_request(struct blk_mq_tag_set * set,struct request * rq,unsigned int hctx_idx,unsigned int numa_node)671 static int virtblk_init_request(struct blk_mq_tag_set *set, struct request *rq,
672 unsigned int hctx_idx, unsigned int numa_node)
673 {
674 struct virtio_blk *vblk = set->driver_data;
675 struct virtblk_req *vbr = blk_mq_rq_to_pdu(rq);
676
677 sg_init_table(vbr->sg, vblk->sg_elems);
678 return 0;
679 }
680
virtblk_map_queues(struct blk_mq_tag_set * set)681 static int virtblk_map_queues(struct blk_mq_tag_set *set)
682 {
683 struct virtio_blk *vblk = set->driver_data;
684
685 return blk_mq_virtio_map_queues(&set->map[HCTX_TYPE_DEFAULT],
686 vblk->vdev, 0);
687 }
688
689 static const struct blk_mq_ops virtio_mq_ops = {
690 .queue_rq = virtio_queue_rq,
691 .commit_rqs = virtio_commit_rqs,
692 .complete = virtblk_request_done,
693 .init_request = virtblk_init_request,
694 .map_queues = virtblk_map_queues,
695 };
696
697 static unsigned int virtblk_queue_depth;
698 module_param_named(queue_depth, virtblk_queue_depth, uint, 0444);
699
virtblk_probe(struct virtio_device * vdev)700 static int virtblk_probe(struct virtio_device *vdev)
701 {
702 struct virtio_blk *vblk;
703 struct request_queue *q;
704 int err, index;
705
706 u32 v, blk_size, max_size, sg_elems, opt_io_size;
707 u16 min_io_size;
708 u8 physical_block_exp, alignment_offset;
709
710 if (!vdev->config->get) {
711 dev_err(&vdev->dev, "%s failure: config access disabled\n",
712 __func__);
713 return -EINVAL;
714 }
715
716 err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS),
717 GFP_KERNEL);
718 if (err < 0)
719 goto out;
720 index = err;
721
722 /* We need to know how many segments before we allocate. */
723 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SEG_MAX,
724 struct virtio_blk_config, seg_max,
725 &sg_elems);
726
727 /* We need at least one SG element, whatever they say. */
728 if (err || !sg_elems)
729 sg_elems = 1;
730
731 /* We need an extra sg elements at head and tail. */
732 sg_elems += 2;
733 vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
734 if (!vblk) {
735 err = -ENOMEM;
736 goto out_free_index;
737 }
738
739 /* This reference is dropped in virtblk_remove(). */
740 refcount_set(&vblk->refs, 1);
741 mutex_init(&vblk->vdev_mutex);
742
743 vblk->vdev = vdev;
744 vblk->sg_elems = sg_elems;
745
746 INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
747
748 err = init_vq(vblk);
749 if (err)
750 goto out_free_vblk;
751
752 /* FIXME: How many partitions? How long is a piece of string? */
753 vblk->disk = alloc_disk(1 << PART_BITS);
754 if (!vblk->disk) {
755 err = -ENOMEM;
756 goto out_free_vq;
757 }
758
759 /* Default queue sizing is to fill the ring. */
760 if (!virtblk_queue_depth) {
761 virtblk_queue_depth = vblk->vqs[0].vq->num_free;
762 /* ... but without indirect descs, we use 2 descs per req */
763 if (!virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC))
764 virtblk_queue_depth /= 2;
765 }
766
767 memset(&vblk->tag_set, 0, sizeof(vblk->tag_set));
768 vblk->tag_set.ops = &virtio_mq_ops;
769 vblk->tag_set.queue_depth = virtblk_queue_depth;
770 vblk->tag_set.numa_node = NUMA_NO_NODE;
771 vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
772 vblk->tag_set.cmd_size =
773 sizeof(struct virtblk_req) +
774 sizeof(struct scatterlist) * sg_elems;
775 vblk->tag_set.driver_data = vblk;
776 vblk->tag_set.nr_hw_queues = vblk->num_vqs;
777
778 err = blk_mq_alloc_tag_set(&vblk->tag_set);
779 if (err)
780 goto out_put_disk;
781
782 q = blk_mq_init_queue(&vblk->tag_set);
783 if (IS_ERR(q)) {
784 err = -ENOMEM;
785 goto out_free_tags;
786 }
787 vblk->disk->queue = q;
788
789 q->queuedata = vblk;
790
791 virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);
792
793 vblk->disk->major = major;
794 vblk->disk->first_minor = index_to_minor(index);
795 vblk->disk->private_data = vblk;
796 vblk->disk->fops = &virtblk_fops;
797 vblk->disk->flags |= GENHD_FL_EXT_DEVT;
798 vblk->index = index;
799
800 /* configure queue flush support */
801 virtblk_update_cache_mode(vdev);
802
803 /* If disk is read-only in the host, the guest should obey */
804 if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
805 set_disk_ro(vblk->disk, 1);
806
807 /* We can handle whatever the host told us to handle. */
808 blk_queue_max_segments(q, vblk->sg_elems-2);
809
810 /* No real sector limit. */
811 blk_queue_max_hw_sectors(q, -1U);
812
813 max_size = virtio_max_dma_size(vdev);
814
815 /* Host can optionally specify maximum segment size and number of
816 * segments. */
817 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SIZE_MAX,
818 struct virtio_blk_config, size_max, &v);
819 if (!err)
820 max_size = min(max_size, v);
821
822 blk_queue_max_segment_size(q, max_size);
823
824 /* Host can optionally specify the block size of the device */
825 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE,
826 struct virtio_blk_config, blk_size,
827 &blk_size);
828 if (!err) {
829 err = blk_validate_block_size(blk_size);
830 if (err) {
831 dev_err(&vdev->dev,
832 "virtio_blk: invalid block size: 0x%x\n",
833 blk_size);
834 goto out_free_tags;
835 }
836
837 blk_queue_logical_block_size(q, blk_size);
838 } else
839 blk_size = queue_logical_block_size(q);
840
841 /* Use topology information if available */
842 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
843 struct virtio_blk_config, physical_block_exp,
844 &physical_block_exp);
845 if (!err && physical_block_exp)
846 blk_queue_physical_block_size(q,
847 blk_size * (1 << physical_block_exp));
848
849 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
850 struct virtio_blk_config, alignment_offset,
851 &alignment_offset);
852 if (!err && alignment_offset)
853 blk_queue_alignment_offset(q, blk_size * alignment_offset);
854
855 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
856 struct virtio_blk_config, min_io_size,
857 &min_io_size);
858 if (!err && min_io_size)
859 blk_queue_io_min(q, blk_size * min_io_size);
860
861 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
862 struct virtio_blk_config, opt_io_size,
863 &opt_io_size);
864 if (!err && opt_io_size)
865 blk_queue_io_opt(q, blk_size * opt_io_size);
866
867 if (virtio_has_feature(vdev, VIRTIO_BLK_F_DISCARD)) {
868 virtio_cread(vdev, struct virtio_blk_config,
869 discard_sector_alignment, &v);
870 if (v)
871 q->limits.discard_granularity = v << SECTOR_SHIFT;
872 else
873 q->limits.discard_granularity = blk_size;
874
875 virtio_cread(vdev, struct virtio_blk_config,
876 max_discard_sectors, &v);
877 blk_queue_max_discard_sectors(q, v ? v : UINT_MAX);
878
879 virtio_cread(vdev, struct virtio_blk_config, max_discard_seg,
880 &v);
881
882 /*
883 * max_discard_seg == 0 is out of spec but we always
884 * handled it.
885 */
886 if (!v)
887 v = sg_elems - 2;
888 blk_queue_max_discard_segments(q,
889 min(v, MAX_DISCARD_SEGMENTS));
890
891 blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
892 }
893
894 if (virtio_has_feature(vdev, VIRTIO_BLK_F_WRITE_ZEROES)) {
895 virtio_cread(vdev, struct virtio_blk_config,
896 max_write_zeroes_sectors, &v);
897 blk_queue_max_write_zeroes_sectors(q, v ? v : UINT_MAX);
898 }
899
900 virtblk_update_capacity(vblk, false);
901 virtio_device_ready(vdev);
902
903 device_add_disk(&vdev->dev, vblk->disk, virtblk_attr_groups);
904 return 0;
905
906 out_free_tags:
907 blk_mq_free_tag_set(&vblk->tag_set);
908 out_put_disk:
909 put_disk(vblk->disk);
910 out_free_vq:
911 vdev->config->del_vqs(vdev);
912 kfree(vblk->vqs);
913 out_free_vblk:
914 kfree(vblk);
915 out_free_index:
916 ida_simple_remove(&vd_index_ida, index);
917 out:
918 return err;
919 }
920
virtblk_remove(struct virtio_device * vdev)921 static void virtblk_remove(struct virtio_device *vdev)
922 {
923 struct virtio_blk *vblk = vdev->priv;
924
925 /* Make sure no work handler is accessing the device. */
926 flush_work(&vblk->config_work);
927
928 del_gendisk(vblk->disk);
929 blk_cleanup_queue(vblk->disk->queue);
930
931 blk_mq_free_tag_set(&vblk->tag_set);
932
933 mutex_lock(&vblk->vdev_mutex);
934
935 /* Stop all the virtqueues. */
936 vdev->config->reset(vdev);
937
938 /* Virtqueues are stopped, nothing can use vblk->vdev anymore. */
939 vblk->vdev = NULL;
940
941 put_disk(vblk->disk);
942 vdev->config->del_vqs(vdev);
943 kfree(vblk->vqs);
944
945 mutex_unlock(&vblk->vdev_mutex);
946
947 virtblk_put(vblk);
948 }
949
950 #ifdef CONFIG_PM_SLEEP
virtblk_freeze(struct virtio_device * vdev)951 static int virtblk_freeze(struct virtio_device *vdev)
952 {
953 struct virtio_blk *vblk = vdev->priv;
954
955 /* Ensure we don't receive any more interrupts */
956 vdev->config->reset(vdev);
957
958 /* Make sure no work handler is accessing the device. */
959 flush_work(&vblk->config_work);
960
961 blk_mq_quiesce_queue(vblk->disk->queue);
962
963 vdev->config->del_vqs(vdev);
964 kfree(vblk->vqs);
965
966 return 0;
967 }
968
virtblk_restore(struct virtio_device * vdev)969 static int virtblk_restore(struct virtio_device *vdev)
970 {
971 struct virtio_blk *vblk = vdev->priv;
972 int ret;
973
974 ret = init_vq(vdev->priv);
975 if (ret)
976 return ret;
977
978 virtio_device_ready(vdev);
979
980 blk_mq_unquiesce_queue(vblk->disk->queue);
981 return 0;
982 }
983 #endif
984
985 static const struct virtio_device_id id_table[] = {
986 { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
987 { 0 },
988 };
989
990 static unsigned int features_legacy[] = {
991 VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
992 VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
993 VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
994 VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
995 }
996 ;
997 static unsigned int features[] = {
998 VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
999 VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
1000 VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
1001 VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
1002 };
1003
1004 static struct virtio_driver virtio_blk = {
1005 .feature_table = features,
1006 .feature_table_size = ARRAY_SIZE(features),
1007 .feature_table_legacy = features_legacy,
1008 .feature_table_size_legacy = ARRAY_SIZE(features_legacy),
1009 .driver.name = KBUILD_MODNAME,
1010 .driver.owner = THIS_MODULE,
1011 .id_table = id_table,
1012 .probe = virtblk_probe,
1013 .remove = virtblk_remove,
1014 .config_changed = virtblk_config_changed,
1015 #ifdef CONFIG_PM_SLEEP
1016 .freeze = virtblk_freeze,
1017 .restore = virtblk_restore,
1018 #endif
1019 };
1020
init(void)1021 static int __init init(void)
1022 {
1023 int error;
1024
1025 virtblk_wq = alloc_workqueue("virtio-blk", 0, 0);
1026 if (!virtblk_wq)
1027 return -ENOMEM;
1028
1029 major = register_blkdev(0, "virtblk");
1030 if (major < 0) {
1031 error = major;
1032 goto out_destroy_workqueue;
1033 }
1034
1035 error = register_virtio_driver(&virtio_blk);
1036 if (error)
1037 goto out_unregister_blkdev;
1038 return 0;
1039
1040 out_unregister_blkdev:
1041 unregister_blkdev(major, "virtblk");
1042 out_destroy_workqueue:
1043 destroy_workqueue(virtblk_wq);
1044 return error;
1045 }
1046
fini(void)1047 static void __exit fini(void)
1048 {
1049 unregister_virtio_driver(&virtio_blk);
1050 unregister_blkdev(major, "virtblk");
1051 destroy_workqueue(virtblk_wq);
1052 }
1053 module_init(init);
1054 module_exit(fini);
1055
1056 MODULE_DEVICE_TABLE(virtio, id_table);
1057 MODULE_DESCRIPTION("Virtio block driver");
1058 MODULE_LICENSE("GPL");
1059