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 /* The maximum number of sg elements that fit into a virtqueue */
25 #define VIRTIO_BLK_MAX_SG_ELEMS 32768
26
27 #ifdef CONFIG_ARCH_NO_SG_CHAIN
28 #define VIRTIO_BLK_INLINE_SG_CNT 0
29 #else
30 #define VIRTIO_BLK_INLINE_SG_CNT 2
31 #endif
32
33 static int major;
34 static DEFINE_IDA(vd_index_ida);
35
36 static struct workqueue_struct *virtblk_wq;
37
38 struct virtio_blk_vq {
39 struct virtqueue *vq;
40 spinlock_t lock;
41 char name[VQ_NAME_LEN];
42 } ____cacheline_aligned_in_smp;
43
44 struct virtio_blk {
45 /*
46 * This mutex must be held by anything that may run after
47 * virtblk_remove() sets vblk->vdev to NULL.
48 *
49 * blk-mq, virtqueue processing, and sysfs attribute code paths are
50 * shut down before vblk->vdev is set to NULL and therefore do not need
51 * to hold this mutex.
52 */
53 struct mutex vdev_mutex;
54 struct virtio_device *vdev;
55
56 /* The disk structure for the kernel. */
57 struct gendisk *disk;
58
59 /* Block layer tags. */
60 struct blk_mq_tag_set tag_set;
61
62 /* Process context for config space updates */
63 struct work_struct config_work;
64
65 /*
66 * Tracks references from block_device_operations open/release and
67 * virtio_driver probe/remove so this object can be freed once no
68 * longer in use.
69 */
70 refcount_t refs;
71
72 /* What host tells us, plus 2 for header & tailer. */
73 unsigned int sg_elems;
74
75 /* Ida index - used to track minor number allocations. */
76 int index;
77
78 /* num of vqs */
79 int num_vqs;
80 struct virtio_blk_vq *vqs;
81 };
82
83 struct virtblk_req {
84 struct virtio_blk_outhdr out_hdr;
85 u8 status;
86 struct sg_table sg_table;
87 struct scatterlist sg[];
88 };
89
virtblk_result(struct virtblk_req * vbr)90 static inline blk_status_t virtblk_result(struct virtblk_req *vbr)
91 {
92 switch (vbr->status) {
93 case VIRTIO_BLK_S_OK:
94 return BLK_STS_OK;
95 case VIRTIO_BLK_S_UNSUPP:
96 return BLK_STS_NOTSUPP;
97 default:
98 return BLK_STS_IOERR;
99 }
100 }
101
virtblk_add_req(struct virtqueue * vq,struct virtblk_req * vbr,struct scatterlist * data_sg,bool have_data)102 static int virtblk_add_req(struct virtqueue *vq, struct virtblk_req *vbr,
103 struct scatterlist *data_sg, bool have_data)
104 {
105 struct scatterlist hdr, status, *sgs[3];
106 unsigned int num_out = 0, num_in = 0;
107
108 sg_init_one(&hdr, &vbr->out_hdr, sizeof(vbr->out_hdr));
109 sgs[num_out++] = &hdr;
110
111 if (have_data) {
112 if (vbr->out_hdr.type & cpu_to_virtio32(vq->vdev, VIRTIO_BLK_T_OUT))
113 sgs[num_out++] = data_sg;
114 else
115 sgs[num_out + num_in++] = data_sg;
116 }
117
118 sg_init_one(&status, &vbr->status, sizeof(vbr->status));
119 sgs[num_out + num_in++] = &status;
120
121 return virtqueue_add_sgs(vq, sgs, num_out, num_in, vbr, GFP_ATOMIC);
122 }
123
virtblk_setup_discard_write_zeroes(struct request * req,bool unmap)124 static int virtblk_setup_discard_write_zeroes(struct request *req, bool unmap)
125 {
126 unsigned short segments = blk_rq_nr_discard_segments(req);
127 unsigned short n = 0;
128 struct virtio_blk_discard_write_zeroes *range;
129 struct bio *bio;
130 u32 flags = 0;
131
132 if (unmap)
133 flags |= VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP;
134
135 range = kmalloc_array(segments, sizeof(*range), GFP_ATOMIC);
136 if (!range)
137 return -ENOMEM;
138
139 /*
140 * Single max discard segment means multi-range discard isn't
141 * supported, and block layer only runs contiguity merge like
142 * normal RW request. So we can't reply on bio for retrieving
143 * each range info.
144 */
145 if (queue_max_discard_segments(req->q) == 1) {
146 range[0].flags = cpu_to_le32(flags);
147 range[0].num_sectors = cpu_to_le32(blk_rq_sectors(req));
148 range[0].sector = cpu_to_le64(blk_rq_pos(req));
149 n = 1;
150 } else {
151 __rq_for_each_bio(bio, req) {
152 u64 sector = bio->bi_iter.bi_sector;
153 u32 num_sectors = bio->bi_iter.bi_size >> SECTOR_SHIFT;
154
155 range[n].flags = cpu_to_le32(flags);
156 range[n].num_sectors = cpu_to_le32(num_sectors);
157 range[n].sector = cpu_to_le64(sector);
158 n++;
159 }
160 }
161
162 WARN_ON_ONCE(n != segments);
163
164 req->special_vec.bv_page = virt_to_page(range);
165 req->special_vec.bv_offset = offset_in_page(range);
166 req->special_vec.bv_len = sizeof(*range) * segments;
167 req->rq_flags |= RQF_SPECIAL_PAYLOAD;
168
169 return 0;
170 }
171
virtblk_unmap_data(struct request * req,struct virtblk_req * vbr)172 static void virtblk_unmap_data(struct request *req, struct virtblk_req *vbr)
173 {
174 if (blk_rq_nr_phys_segments(req))
175 sg_free_table_chained(&vbr->sg_table,
176 VIRTIO_BLK_INLINE_SG_CNT);
177 }
178
virtblk_map_data(struct blk_mq_hw_ctx * hctx,struct request * req,struct virtblk_req * vbr)179 static int virtblk_map_data(struct blk_mq_hw_ctx *hctx, struct request *req,
180 struct virtblk_req *vbr)
181 {
182 int err;
183
184 if (!blk_rq_nr_phys_segments(req))
185 return 0;
186
187 vbr->sg_table.sgl = vbr->sg;
188 err = sg_alloc_table_chained(&vbr->sg_table,
189 blk_rq_nr_phys_segments(req),
190 vbr->sg_table.sgl,
191 VIRTIO_BLK_INLINE_SG_CNT);
192 if (unlikely(err))
193 return -ENOMEM;
194
195 return blk_rq_map_sg(hctx->queue, req, vbr->sg_table.sgl);
196 }
197
virtblk_cleanup_cmd(struct request * req)198 static void virtblk_cleanup_cmd(struct request *req)
199 {
200 if (req->rq_flags & RQF_SPECIAL_PAYLOAD)
201 kfree(bvec_virt(&req->special_vec));
202 }
203
virtblk_setup_cmd(struct virtio_device * vdev,struct request * req,struct virtblk_req * vbr)204 static int virtblk_setup_cmd(struct virtio_device *vdev, struct request *req,
205 struct virtblk_req *vbr)
206 {
207 bool unmap = false;
208 u32 type;
209
210 vbr->out_hdr.sector = 0;
211
212 switch (req_op(req)) {
213 case REQ_OP_READ:
214 type = VIRTIO_BLK_T_IN;
215 vbr->out_hdr.sector = cpu_to_virtio64(vdev,
216 blk_rq_pos(req));
217 break;
218 case REQ_OP_WRITE:
219 type = VIRTIO_BLK_T_OUT;
220 vbr->out_hdr.sector = cpu_to_virtio64(vdev,
221 blk_rq_pos(req));
222 break;
223 case REQ_OP_FLUSH:
224 type = VIRTIO_BLK_T_FLUSH;
225 break;
226 case REQ_OP_DISCARD:
227 type = VIRTIO_BLK_T_DISCARD;
228 break;
229 case REQ_OP_WRITE_ZEROES:
230 type = VIRTIO_BLK_T_WRITE_ZEROES;
231 unmap = !(req->cmd_flags & REQ_NOUNMAP);
232 break;
233 case REQ_OP_DRV_IN:
234 type = VIRTIO_BLK_T_GET_ID;
235 break;
236 default:
237 WARN_ON_ONCE(1);
238 return BLK_STS_IOERR;
239 }
240
241 vbr->out_hdr.type = cpu_to_virtio32(vdev, type);
242 vbr->out_hdr.ioprio = cpu_to_virtio32(vdev, req_get_ioprio(req));
243
244 if (type == VIRTIO_BLK_T_DISCARD || type == VIRTIO_BLK_T_WRITE_ZEROES) {
245 if (virtblk_setup_discard_write_zeroes(req, unmap))
246 return BLK_STS_RESOURCE;
247 }
248
249 return 0;
250 }
251
virtblk_request_done(struct request * req)252 static inline void virtblk_request_done(struct request *req)
253 {
254 struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
255
256 virtblk_unmap_data(req, vbr);
257 virtblk_cleanup_cmd(req);
258 blk_mq_end_request(req, virtblk_result(vbr));
259 }
260
virtblk_done(struct virtqueue * vq)261 static void virtblk_done(struct virtqueue *vq)
262 {
263 struct virtio_blk *vblk = vq->vdev->priv;
264 bool req_done = false;
265 int qid = vq->index;
266 struct virtblk_req *vbr;
267 unsigned long flags;
268 unsigned int len;
269
270 spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
271 do {
272 virtqueue_disable_cb(vq);
273 while ((vbr = virtqueue_get_buf(vblk->vqs[qid].vq, &len)) != NULL) {
274 struct request *req = blk_mq_rq_from_pdu(vbr);
275
276 if (likely(!blk_should_fake_timeout(req->q)))
277 blk_mq_complete_request(req);
278 req_done = true;
279 }
280 if (unlikely(virtqueue_is_broken(vq)))
281 break;
282 } while (!virtqueue_enable_cb(vq));
283
284 /* In case queue is stopped waiting for more buffers. */
285 if (req_done)
286 blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
287 spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
288 }
289
virtio_commit_rqs(struct blk_mq_hw_ctx * hctx)290 static void virtio_commit_rqs(struct blk_mq_hw_ctx *hctx)
291 {
292 struct virtio_blk *vblk = hctx->queue->queuedata;
293 struct virtio_blk_vq *vq = &vblk->vqs[hctx->queue_num];
294 bool kick;
295
296 spin_lock_irq(&vq->lock);
297 kick = virtqueue_kick_prepare(vq->vq);
298 spin_unlock_irq(&vq->lock);
299
300 if (kick)
301 virtqueue_notify(vq->vq);
302 }
303
virtio_queue_rq(struct blk_mq_hw_ctx * hctx,const struct blk_mq_queue_data * bd)304 static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
305 const struct blk_mq_queue_data *bd)
306 {
307 struct virtio_blk *vblk = hctx->queue->queuedata;
308 struct request *req = bd->rq;
309 struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
310 unsigned long flags;
311 int num;
312 int qid = hctx->queue_num;
313 int err;
314 bool notify = false;
315
316 err = virtblk_setup_cmd(vblk->vdev, req, vbr);
317 if (unlikely(err))
318 return err;
319
320 blk_mq_start_request(req);
321
322 num = virtblk_map_data(hctx, req, vbr);
323 if (unlikely(num < 0)) {
324 virtblk_cleanup_cmd(req);
325 return BLK_STS_RESOURCE;
326 }
327
328 spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
329 err = virtblk_add_req(vblk->vqs[qid].vq, vbr, vbr->sg_table.sgl, num);
330 if (err) {
331 virtqueue_kick(vblk->vqs[qid].vq);
332 /* Don't stop the queue if -ENOMEM: we may have failed to
333 * bounce the buffer due to global resource outage.
334 */
335 if (err == -ENOSPC)
336 blk_mq_stop_hw_queue(hctx);
337 spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
338 virtblk_unmap_data(req, vbr);
339 virtblk_cleanup_cmd(req);
340 switch (err) {
341 case -ENOSPC:
342 return BLK_STS_DEV_RESOURCE;
343 case -ENOMEM:
344 return BLK_STS_RESOURCE;
345 default:
346 return BLK_STS_IOERR;
347 }
348 }
349
350 if (bd->last && virtqueue_kick_prepare(vblk->vqs[qid].vq))
351 notify = true;
352 spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
353
354 if (notify)
355 virtqueue_notify(vblk->vqs[qid].vq);
356 return BLK_STS_OK;
357 }
358
359 /* return id (s/n) string for *disk to *id_str
360 */
virtblk_get_id(struct gendisk * disk,char * id_str)361 static int virtblk_get_id(struct gendisk *disk, char *id_str)
362 {
363 struct virtio_blk *vblk = disk->private_data;
364 struct request_queue *q = vblk->disk->queue;
365 struct request *req;
366 int err;
367
368 req = blk_get_request(q, REQ_OP_DRV_IN, 0);
369 if (IS_ERR(req))
370 return PTR_ERR(req);
371
372 err = blk_rq_map_kern(q, req, id_str, VIRTIO_BLK_ID_BYTES, GFP_KERNEL);
373 if (err)
374 goto out;
375
376 blk_execute_rq(vblk->disk, req, false);
377 err = blk_status_to_errno(virtblk_result(blk_mq_rq_to_pdu(req)));
378 out:
379 blk_put_request(req);
380 return err;
381 }
382
virtblk_get(struct virtio_blk * vblk)383 static void virtblk_get(struct virtio_blk *vblk)
384 {
385 refcount_inc(&vblk->refs);
386 }
387
virtblk_put(struct virtio_blk * vblk)388 static void virtblk_put(struct virtio_blk *vblk)
389 {
390 if (refcount_dec_and_test(&vblk->refs)) {
391 ida_simple_remove(&vd_index_ida, vblk->index);
392 mutex_destroy(&vblk->vdev_mutex);
393 kfree(vblk);
394 }
395 }
396
virtblk_open(struct block_device * bd,fmode_t mode)397 static int virtblk_open(struct block_device *bd, fmode_t mode)
398 {
399 struct virtio_blk *vblk = bd->bd_disk->private_data;
400 int ret = 0;
401
402 mutex_lock(&vblk->vdev_mutex);
403
404 if (vblk->vdev)
405 virtblk_get(vblk);
406 else
407 ret = -ENXIO;
408
409 mutex_unlock(&vblk->vdev_mutex);
410 return ret;
411 }
412
virtblk_release(struct gendisk * disk,fmode_t mode)413 static void virtblk_release(struct gendisk *disk, fmode_t mode)
414 {
415 struct virtio_blk *vblk = disk->private_data;
416
417 virtblk_put(vblk);
418 }
419
420 /* We provide getgeo only to please some old bootloader/partitioning tools */
virtblk_getgeo(struct block_device * bd,struct hd_geometry * geo)421 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
422 {
423 struct virtio_blk *vblk = bd->bd_disk->private_data;
424 int ret = 0;
425
426 mutex_lock(&vblk->vdev_mutex);
427
428 if (!vblk->vdev) {
429 ret = -ENXIO;
430 goto out;
431 }
432
433 /* see if the host passed in geometry config */
434 if (virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_GEOMETRY)) {
435 virtio_cread(vblk->vdev, struct virtio_blk_config,
436 geometry.cylinders, &geo->cylinders);
437 virtio_cread(vblk->vdev, struct virtio_blk_config,
438 geometry.heads, &geo->heads);
439 virtio_cread(vblk->vdev, struct virtio_blk_config,
440 geometry.sectors, &geo->sectors);
441 } else {
442 /* some standard values, similar to sd */
443 geo->heads = 1 << 6;
444 geo->sectors = 1 << 5;
445 geo->cylinders = get_capacity(bd->bd_disk) >> 11;
446 }
447 out:
448 mutex_unlock(&vblk->vdev_mutex);
449 return ret;
450 }
451
452 static const struct block_device_operations virtblk_fops = {
453 .owner = THIS_MODULE,
454 .open = virtblk_open,
455 .release = virtblk_release,
456 .getgeo = virtblk_getgeo,
457 };
458
index_to_minor(int index)459 static int index_to_minor(int index)
460 {
461 return index << PART_BITS;
462 }
463
minor_to_index(int minor)464 static int minor_to_index(int minor)
465 {
466 return minor >> PART_BITS;
467 }
468
serial_show(struct device * dev,struct device_attribute * attr,char * buf)469 static ssize_t serial_show(struct device *dev,
470 struct device_attribute *attr, char *buf)
471 {
472 struct gendisk *disk = dev_to_disk(dev);
473 int err;
474
475 /* sysfs gives us a PAGE_SIZE buffer */
476 BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);
477
478 buf[VIRTIO_BLK_ID_BYTES] = '\0';
479 err = virtblk_get_id(disk, buf);
480 if (!err)
481 return strlen(buf);
482
483 if (err == -EIO) /* Unsupported? Make it empty. */
484 return 0;
485
486 return err;
487 }
488
489 static DEVICE_ATTR_RO(serial);
490
491 /* The queue's logical block size must be set before calling this */
virtblk_update_capacity(struct virtio_blk * vblk,bool resize)492 static void virtblk_update_capacity(struct virtio_blk *vblk, bool resize)
493 {
494 struct virtio_device *vdev = vblk->vdev;
495 struct request_queue *q = vblk->disk->queue;
496 char cap_str_2[10], cap_str_10[10];
497 unsigned long long nblocks;
498 u64 capacity;
499
500 /* Host must always specify the capacity. */
501 virtio_cread(vdev, struct virtio_blk_config, capacity, &capacity);
502
503 nblocks = DIV_ROUND_UP_ULL(capacity, queue_logical_block_size(q) >> 9);
504
505 string_get_size(nblocks, queue_logical_block_size(q),
506 STRING_UNITS_2, cap_str_2, sizeof(cap_str_2));
507 string_get_size(nblocks, queue_logical_block_size(q),
508 STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));
509
510 dev_notice(&vdev->dev,
511 "[%s] %s%llu %d-byte logical blocks (%s/%s)\n",
512 vblk->disk->disk_name,
513 resize ? "new size: " : "",
514 nblocks,
515 queue_logical_block_size(q),
516 cap_str_10,
517 cap_str_2);
518
519 set_capacity_and_notify(vblk->disk, capacity);
520 }
521
virtblk_config_changed_work(struct work_struct * work)522 static void virtblk_config_changed_work(struct work_struct *work)
523 {
524 struct virtio_blk *vblk =
525 container_of(work, struct virtio_blk, config_work);
526
527 virtblk_update_capacity(vblk, true);
528 }
529
virtblk_config_changed(struct virtio_device * vdev)530 static void virtblk_config_changed(struct virtio_device *vdev)
531 {
532 struct virtio_blk *vblk = vdev->priv;
533
534 queue_work(virtblk_wq, &vblk->config_work);
535 }
536
init_vq(struct virtio_blk * vblk)537 static int init_vq(struct virtio_blk *vblk)
538 {
539 int err;
540 int i;
541 vq_callback_t **callbacks;
542 const char **names;
543 struct virtqueue **vqs;
544 unsigned short num_vqs;
545 struct virtio_device *vdev = vblk->vdev;
546 struct irq_affinity desc = { 0, };
547
548 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_MQ,
549 struct virtio_blk_config, num_queues,
550 &num_vqs);
551 if (err)
552 num_vqs = 1;
553 if (!err && !num_vqs) {
554 dev_err(&vdev->dev, "MQ advertisted but zero queues reported\n");
555 return -EINVAL;
556 }
557
558 num_vqs = min_t(unsigned int, nr_cpu_ids, num_vqs);
559
560 vblk->vqs = kmalloc_array(num_vqs, sizeof(*vblk->vqs), GFP_KERNEL);
561 if (!vblk->vqs)
562 return -ENOMEM;
563
564 names = kmalloc_array(num_vqs, sizeof(*names), GFP_KERNEL);
565 callbacks = kmalloc_array(num_vqs, sizeof(*callbacks), GFP_KERNEL);
566 vqs = kmalloc_array(num_vqs, sizeof(*vqs), GFP_KERNEL);
567 if (!names || !callbacks || !vqs) {
568 err = -ENOMEM;
569 goto out;
570 }
571
572 for (i = 0; i < num_vqs; i++) {
573 callbacks[i] = virtblk_done;
574 snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req.%d", i);
575 names[i] = vblk->vqs[i].name;
576 }
577
578 /* Discover virtqueues and write information to configuration. */
579 err = virtio_find_vqs(vdev, num_vqs, vqs, callbacks, names, &desc);
580 if (err)
581 goto out;
582
583 for (i = 0; i < num_vqs; i++) {
584 spin_lock_init(&vblk->vqs[i].lock);
585 vblk->vqs[i].vq = vqs[i];
586 }
587 vblk->num_vqs = num_vqs;
588
589 out:
590 kfree(vqs);
591 kfree(callbacks);
592 kfree(names);
593 if (err)
594 kfree(vblk->vqs);
595 return err;
596 }
597
598 /*
599 * Legacy naming scheme used for virtio devices. We are stuck with it for
600 * virtio blk but don't ever use it for any new driver.
601 */
virtblk_name_format(char * prefix,int index,char * buf,int buflen)602 static int virtblk_name_format(char *prefix, int index, char *buf, int buflen)
603 {
604 const int base = 'z' - 'a' + 1;
605 char *begin = buf + strlen(prefix);
606 char *end = buf + buflen;
607 char *p;
608 int unit;
609
610 p = end - 1;
611 *p = '\0';
612 unit = base;
613 do {
614 if (p == begin)
615 return -EINVAL;
616 *--p = 'a' + (index % unit);
617 index = (index / unit) - 1;
618 } while (index >= 0);
619
620 memmove(begin, p, end - p);
621 memcpy(buf, prefix, strlen(prefix));
622
623 return 0;
624 }
625
virtblk_get_cache_mode(struct virtio_device * vdev)626 static int virtblk_get_cache_mode(struct virtio_device *vdev)
627 {
628 u8 writeback;
629 int err;
630
631 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE,
632 struct virtio_blk_config, wce,
633 &writeback);
634
635 /*
636 * If WCE is not configurable and flush is not available,
637 * assume no writeback cache is in use.
638 */
639 if (err)
640 writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH);
641
642 return writeback;
643 }
644
virtblk_update_cache_mode(struct virtio_device * vdev)645 static void virtblk_update_cache_mode(struct virtio_device *vdev)
646 {
647 u8 writeback = virtblk_get_cache_mode(vdev);
648 struct virtio_blk *vblk = vdev->priv;
649
650 blk_queue_write_cache(vblk->disk->queue, writeback, false);
651 }
652
653 static const char *const virtblk_cache_types[] = {
654 "write through", "write back"
655 };
656
657 static ssize_t
cache_type_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)658 cache_type_store(struct device *dev, struct device_attribute *attr,
659 const char *buf, size_t count)
660 {
661 struct gendisk *disk = dev_to_disk(dev);
662 struct virtio_blk *vblk = disk->private_data;
663 struct virtio_device *vdev = vblk->vdev;
664 int i;
665
666 BUG_ON(!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_CONFIG_WCE));
667 i = sysfs_match_string(virtblk_cache_types, buf);
668 if (i < 0)
669 return i;
670
671 virtio_cwrite8(vdev, offsetof(struct virtio_blk_config, wce), i);
672 virtblk_update_cache_mode(vdev);
673 return count;
674 }
675
676 static ssize_t
cache_type_show(struct device * dev,struct device_attribute * attr,char * buf)677 cache_type_show(struct device *dev, struct device_attribute *attr, char *buf)
678 {
679 struct gendisk *disk = dev_to_disk(dev);
680 struct virtio_blk *vblk = disk->private_data;
681 u8 writeback = virtblk_get_cache_mode(vblk->vdev);
682
683 BUG_ON(writeback >= ARRAY_SIZE(virtblk_cache_types));
684 return snprintf(buf, 40, "%s\n", virtblk_cache_types[writeback]);
685 }
686
687 static DEVICE_ATTR_RW(cache_type);
688
689 static struct attribute *virtblk_attrs[] = {
690 &dev_attr_serial.attr,
691 &dev_attr_cache_type.attr,
692 NULL,
693 };
694
virtblk_attrs_are_visible(struct kobject * kobj,struct attribute * a,int n)695 static umode_t virtblk_attrs_are_visible(struct kobject *kobj,
696 struct attribute *a, int n)
697 {
698 struct device *dev = kobj_to_dev(kobj);
699 struct gendisk *disk = dev_to_disk(dev);
700 struct virtio_blk *vblk = disk->private_data;
701 struct virtio_device *vdev = vblk->vdev;
702
703 if (a == &dev_attr_cache_type.attr &&
704 !virtio_has_feature(vdev, VIRTIO_BLK_F_CONFIG_WCE))
705 return S_IRUGO;
706
707 return a->mode;
708 }
709
710 static const struct attribute_group virtblk_attr_group = {
711 .attrs = virtblk_attrs,
712 .is_visible = virtblk_attrs_are_visible,
713 };
714
715 static const struct attribute_group *virtblk_attr_groups[] = {
716 &virtblk_attr_group,
717 NULL,
718 };
719
virtblk_map_queues(struct blk_mq_tag_set * set)720 static int virtblk_map_queues(struct blk_mq_tag_set *set)
721 {
722 struct virtio_blk *vblk = set->driver_data;
723
724 return blk_mq_virtio_map_queues(&set->map[HCTX_TYPE_DEFAULT],
725 vblk->vdev, 0);
726 }
727
728 static const struct blk_mq_ops virtio_mq_ops = {
729 .queue_rq = virtio_queue_rq,
730 .commit_rqs = virtio_commit_rqs,
731 .complete = virtblk_request_done,
732 .map_queues = virtblk_map_queues,
733 };
734
735 static unsigned int virtblk_queue_depth;
736 module_param_named(queue_depth, virtblk_queue_depth, uint, 0444);
737
virtblk_probe(struct virtio_device * vdev)738 static int virtblk_probe(struct virtio_device *vdev)
739 {
740 struct virtio_blk *vblk;
741 struct request_queue *q;
742 int err, index;
743
744 u32 v, blk_size, max_size, sg_elems, opt_io_size;
745 u16 min_io_size;
746 u8 physical_block_exp, alignment_offset;
747 unsigned int queue_depth;
748 size_t max_dma_size;
749
750 if (!vdev->config->get) {
751 dev_err(&vdev->dev, "%s failure: config access disabled\n",
752 __func__);
753 return -EINVAL;
754 }
755
756 err = ida_simple_get(&vd_index_ida, 0, minor_to_index(1 << MINORBITS),
757 GFP_KERNEL);
758 if (err < 0)
759 goto out;
760 index = err;
761
762 /* We need to know how many segments before we allocate. */
763 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SEG_MAX,
764 struct virtio_blk_config, seg_max,
765 &sg_elems);
766
767 /* We need at least one SG element, whatever they say. */
768 if (err || !sg_elems)
769 sg_elems = 1;
770
771 /* Prevent integer overflows and honor max vq size */
772 sg_elems = min_t(u32, sg_elems, VIRTIO_BLK_MAX_SG_ELEMS - 2);
773
774 /* We need extra sg elements at head and tail. */
775 sg_elems += 2;
776 vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
777 if (!vblk) {
778 err = -ENOMEM;
779 goto out_free_index;
780 }
781
782 /* This reference is dropped in virtblk_remove(). */
783 refcount_set(&vblk->refs, 1);
784 mutex_init(&vblk->vdev_mutex);
785
786 vblk->vdev = vdev;
787 vblk->sg_elems = sg_elems;
788
789 INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
790
791 err = init_vq(vblk);
792 if (err)
793 goto out_free_vblk;
794
795 /* Default queue sizing is to fill the ring. */
796 if (!virtblk_queue_depth) {
797 queue_depth = vblk->vqs[0].vq->num_free;
798 /* ... but without indirect descs, we use 2 descs per req */
799 if (!virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC))
800 queue_depth /= 2;
801 } else {
802 queue_depth = virtblk_queue_depth;
803 }
804
805 memset(&vblk->tag_set, 0, sizeof(vblk->tag_set));
806 vblk->tag_set.ops = &virtio_mq_ops;
807 vblk->tag_set.queue_depth = queue_depth;
808 vblk->tag_set.numa_node = NUMA_NO_NODE;
809 vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
810 vblk->tag_set.cmd_size =
811 sizeof(struct virtblk_req) +
812 sizeof(struct scatterlist) * VIRTIO_BLK_INLINE_SG_CNT;
813 vblk->tag_set.driver_data = vblk;
814 vblk->tag_set.nr_hw_queues = vblk->num_vqs;
815
816 err = blk_mq_alloc_tag_set(&vblk->tag_set);
817 if (err)
818 goto out_free_vq;
819
820 vblk->disk = blk_mq_alloc_disk(&vblk->tag_set, vblk);
821 if (IS_ERR(vblk->disk)) {
822 err = PTR_ERR(vblk->disk);
823 goto out_free_tags;
824 }
825 q = vblk->disk->queue;
826
827 virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);
828
829 vblk->disk->major = major;
830 vblk->disk->first_minor = index_to_minor(index);
831 vblk->disk->minors = 1 << PART_BITS;
832 vblk->disk->private_data = vblk;
833 vblk->disk->fops = &virtblk_fops;
834 vblk->disk->flags |= GENHD_FL_EXT_DEVT;
835 vblk->index = index;
836
837 /* configure queue flush support */
838 virtblk_update_cache_mode(vdev);
839
840 /* If disk is read-only in the host, the guest should obey */
841 if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
842 set_disk_ro(vblk->disk, 1);
843
844 /* We can handle whatever the host told us to handle. */
845 blk_queue_max_segments(q, vblk->sg_elems-2);
846
847 /* No real sector limit. */
848 blk_queue_max_hw_sectors(q, -1U);
849
850 max_dma_size = virtio_max_dma_size(vdev);
851 max_size = max_dma_size > U32_MAX ? U32_MAX : max_dma_size;
852
853 /* Host can optionally specify maximum segment size and number of
854 * segments. */
855 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SIZE_MAX,
856 struct virtio_blk_config, size_max, &v);
857 if (!err)
858 max_size = min(max_size, v);
859
860 blk_queue_max_segment_size(q, max_size);
861
862 /* Host can optionally specify the block size of the device */
863 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_BLK_SIZE,
864 struct virtio_blk_config, blk_size,
865 &blk_size);
866 if (!err) {
867 err = blk_validate_block_size(blk_size);
868 if (err) {
869 dev_err(&vdev->dev,
870 "virtio_blk: invalid block size: 0x%x\n",
871 blk_size);
872 goto out_cleanup_disk;
873 }
874
875 blk_queue_logical_block_size(q, blk_size);
876 } else
877 blk_size = queue_logical_block_size(q);
878
879 /* Use topology information if available */
880 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
881 struct virtio_blk_config, physical_block_exp,
882 &physical_block_exp);
883 if (!err && physical_block_exp)
884 blk_queue_physical_block_size(q,
885 blk_size * (1 << physical_block_exp));
886
887 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
888 struct virtio_blk_config, alignment_offset,
889 &alignment_offset);
890 if (!err && alignment_offset)
891 blk_queue_alignment_offset(q, blk_size * alignment_offset);
892
893 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
894 struct virtio_blk_config, min_io_size,
895 &min_io_size);
896 if (!err && min_io_size)
897 blk_queue_io_min(q, blk_size * min_io_size);
898
899 err = virtio_cread_feature(vdev, VIRTIO_BLK_F_TOPOLOGY,
900 struct virtio_blk_config, opt_io_size,
901 &opt_io_size);
902 if (!err && opt_io_size)
903 blk_queue_io_opt(q, blk_size * opt_io_size);
904
905 if (virtio_has_feature(vdev, VIRTIO_BLK_F_DISCARD)) {
906 virtio_cread(vdev, struct virtio_blk_config,
907 discard_sector_alignment, &v);
908 if (v)
909 q->limits.discard_granularity = v << SECTOR_SHIFT;
910 else
911 q->limits.discard_granularity = blk_size;
912
913 virtio_cread(vdev, struct virtio_blk_config,
914 max_discard_sectors, &v);
915 blk_queue_max_discard_sectors(q, v ? v : UINT_MAX);
916
917 virtio_cread(vdev, struct virtio_blk_config, max_discard_seg,
918 &v);
919
920 /*
921 * max_discard_seg == 0 is out of spec but we always
922 * handled it.
923 */
924 if (!v)
925 v = sg_elems - 2;
926 blk_queue_max_discard_segments(q,
927 min(v, MAX_DISCARD_SEGMENTS));
928
929 blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
930 }
931
932 if (virtio_has_feature(vdev, VIRTIO_BLK_F_WRITE_ZEROES)) {
933 virtio_cread(vdev, struct virtio_blk_config,
934 max_write_zeroes_sectors, &v);
935 blk_queue_max_write_zeroes_sectors(q, v ? v : UINT_MAX);
936 }
937
938 virtblk_update_capacity(vblk, false);
939 virtio_device_ready(vdev);
940
941 err = device_add_disk(&vdev->dev, vblk->disk, virtblk_attr_groups);
942 if (err)
943 goto out_cleanup_disk;
944
945 return 0;
946
947 out_cleanup_disk:
948 blk_cleanup_disk(vblk->disk);
949 out_free_tags:
950 blk_mq_free_tag_set(&vblk->tag_set);
951 out_free_vq:
952 vdev->config->del_vqs(vdev);
953 kfree(vblk->vqs);
954 out_free_vblk:
955 kfree(vblk);
956 out_free_index:
957 ida_simple_remove(&vd_index_ida, index);
958 out:
959 return err;
960 }
961
virtblk_remove(struct virtio_device * vdev)962 static void virtblk_remove(struct virtio_device *vdev)
963 {
964 struct virtio_blk *vblk = vdev->priv;
965
966 /* Make sure no work handler is accessing the device. */
967 flush_work(&vblk->config_work);
968
969 del_gendisk(vblk->disk);
970 blk_cleanup_disk(vblk->disk);
971 blk_mq_free_tag_set(&vblk->tag_set);
972
973 mutex_lock(&vblk->vdev_mutex);
974
975 /* Stop all the virtqueues. */
976 vdev->config->reset(vdev);
977
978 /* Virtqueues are stopped, nothing can use vblk->vdev anymore. */
979 vblk->vdev = NULL;
980
981 vdev->config->del_vqs(vdev);
982 kfree(vblk->vqs);
983
984 mutex_unlock(&vblk->vdev_mutex);
985
986 virtblk_put(vblk);
987 }
988
989 #ifdef CONFIG_PM_SLEEP
virtblk_freeze(struct virtio_device * vdev)990 static int virtblk_freeze(struct virtio_device *vdev)
991 {
992 struct virtio_blk *vblk = vdev->priv;
993
994 /* Ensure we don't receive any more interrupts */
995 vdev->config->reset(vdev);
996
997 /* Make sure no work handler is accessing the device. */
998 flush_work(&vblk->config_work);
999
1000 blk_mq_quiesce_queue(vblk->disk->queue);
1001
1002 vdev->config->del_vqs(vdev);
1003 kfree(vblk->vqs);
1004
1005 return 0;
1006 }
1007
virtblk_restore(struct virtio_device * vdev)1008 static int virtblk_restore(struct virtio_device *vdev)
1009 {
1010 struct virtio_blk *vblk = vdev->priv;
1011 int ret;
1012
1013 ret = init_vq(vdev->priv);
1014 if (ret)
1015 return ret;
1016
1017 virtio_device_ready(vdev);
1018
1019 blk_mq_unquiesce_queue(vblk->disk->queue);
1020 return 0;
1021 }
1022 #endif
1023
1024 static const struct virtio_device_id id_table[] = {
1025 { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
1026 { 0 },
1027 };
1028
1029 static unsigned int features_legacy[] = {
1030 VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
1031 VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
1032 VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
1033 VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
1034 }
1035 ;
1036 static unsigned int features[] = {
1037 VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
1038 VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
1039 VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
1040 VIRTIO_BLK_F_MQ, VIRTIO_BLK_F_DISCARD, VIRTIO_BLK_F_WRITE_ZEROES,
1041 };
1042
1043 static struct virtio_driver virtio_blk = {
1044 .feature_table = features,
1045 .feature_table_size = ARRAY_SIZE(features),
1046 .feature_table_legacy = features_legacy,
1047 .feature_table_size_legacy = ARRAY_SIZE(features_legacy),
1048 .driver.name = KBUILD_MODNAME,
1049 .driver.owner = THIS_MODULE,
1050 .id_table = id_table,
1051 .probe = virtblk_probe,
1052 .remove = virtblk_remove,
1053 .config_changed = virtblk_config_changed,
1054 #ifdef CONFIG_PM_SLEEP
1055 .freeze = virtblk_freeze,
1056 .restore = virtblk_restore,
1057 #endif
1058 };
1059
init(void)1060 static int __init init(void)
1061 {
1062 int error;
1063
1064 virtblk_wq = alloc_workqueue("virtio-blk", 0, 0);
1065 if (!virtblk_wq)
1066 return -ENOMEM;
1067
1068 major = register_blkdev(0, "virtblk");
1069 if (major < 0) {
1070 error = major;
1071 goto out_destroy_workqueue;
1072 }
1073
1074 error = register_virtio_driver(&virtio_blk);
1075 if (error)
1076 goto out_unregister_blkdev;
1077 return 0;
1078
1079 out_unregister_blkdev:
1080 unregister_blkdev(major, "virtblk");
1081 out_destroy_workqueue:
1082 destroy_workqueue(virtblk_wq);
1083 return error;
1084 }
1085
fini(void)1086 static void __exit fini(void)
1087 {
1088 unregister_virtio_driver(&virtio_blk);
1089 unregister_blkdev(major, "virtblk");
1090 destroy_workqueue(virtblk_wq);
1091 }
1092 module_init(init);
1093 module_exit(fini);
1094
1095 MODULE_DEVICE_TABLE(virtio, id_table);
1096 MODULE_DESCRIPTION("Virtio block driver");
1097 MODULE_LICENSE("GPL");
1098