1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Block driver for s390 storage class memory.
4 *
5 * Copyright IBM Corp. 2012
6 * Author(s): Sebastian Ott <sebott@linux.vnet.ibm.com>
7 */
8
9 #define KMSG_COMPONENT "scm_block"
10 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
11
12 #include <linux/interrupt.h>
13 #include <linux/spinlock.h>
14 #include <linux/mempool.h>
15 #include <linux/module.h>
16 #include <linux/blkdev.h>
17 #include <linux/blk-mq.h>
18 #include <linux/slab.h>
19 #include <linux/list.h>
20 #include <linux/io.h>
21 #include <asm/eadm.h>
22 #include "scm_blk.h"
23
24 debug_info_t *scm_debug;
25 static int scm_major;
26 static mempool_t *aidaw_pool;
27 static DEFINE_SPINLOCK(list_lock);
28 static LIST_HEAD(inactive_requests);
29 static unsigned int nr_requests = 64;
30 static unsigned int nr_requests_per_io = 8;
31 static atomic_t nr_devices = ATOMIC_INIT(0);
32 module_param(nr_requests, uint, S_IRUGO);
33 MODULE_PARM_DESC(nr_requests, "Number of parallel requests.");
34
35 module_param(nr_requests_per_io, uint, S_IRUGO);
36 MODULE_PARM_DESC(nr_requests_per_io, "Number of requests per IO.");
37
38 MODULE_DESCRIPTION("Block driver for s390 storage class memory.");
39 MODULE_LICENSE("GPL");
40 MODULE_ALIAS("scm:scmdev*");
41
__scm_free_rq(struct scm_request * scmrq)42 static void __scm_free_rq(struct scm_request *scmrq)
43 {
44 struct aob_rq_header *aobrq = to_aobrq(scmrq);
45
46 free_page((unsigned long) scmrq->aob);
47 kfree(scmrq->request);
48 kfree(aobrq);
49 }
50
scm_free_rqs(void)51 static void scm_free_rqs(void)
52 {
53 struct list_head *iter, *safe;
54 struct scm_request *scmrq;
55
56 spin_lock_irq(&list_lock);
57 list_for_each_safe(iter, safe, &inactive_requests) {
58 scmrq = list_entry(iter, struct scm_request, list);
59 list_del(&scmrq->list);
60 __scm_free_rq(scmrq);
61 }
62 spin_unlock_irq(&list_lock);
63
64 mempool_destroy(aidaw_pool);
65 }
66
__scm_alloc_rq(void)67 static int __scm_alloc_rq(void)
68 {
69 struct aob_rq_header *aobrq;
70 struct scm_request *scmrq;
71
72 aobrq = kzalloc(sizeof(*aobrq) + sizeof(*scmrq), GFP_KERNEL);
73 if (!aobrq)
74 return -ENOMEM;
75
76 scmrq = (void *) aobrq->data;
77 scmrq->aob = (void *) get_zeroed_page(GFP_DMA);
78 if (!scmrq->aob)
79 goto free;
80
81 scmrq->request = kcalloc(nr_requests_per_io, sizeof(scmrq->request[0]),
82 GFP_KERNEL);
83 if (!scmrq->request)
84 goto free;
85
86 INIT_LIST_HEAD(&scmrq->list);
87 spin_lock_irq(&list_lock);
88 list_add(&scmrq->list, &inactive_requests);
89 spin_unlock_irq(&list_lock);
90
91 return 0;
92 free:
93 __scm_free_rq(scmrq);
94 return -ENOMEM;
95 }
96
scm_alloc_rqs(unsigned int nrqs)97 static int scm_alloc_rqs(unsigned int nrqs)
98 {
99 int ret = 0;
100
101 aidaw_pool = mempool_create_page_pool(max(nrqs/8, 1U), 0);
102 if (!aidaw_pool)
103 return -ENOMEM;
104
105 while (nrqs-- && !ret)
106 ret = __scm_alloc_rq();
107
108 return ret;
109 }
110
scm_request_fetch(void)111 static struct scm_request *scm_request_fetch(void)
112 {
113 struct scm_request *scmrq = NULL;
114
115 spin_lock_irq(&list_lock);
116 if (list_empty(&inactive_requests))
117 goto out;
118 scmrq = list_first_entry(&inactive_requests, struct scm_request, list);
119 list_del(&scmrq->list);
120 out:
121 spin_unlock_irq(&list_lock);
122 return scmrq;
123 }
124
scm_request_done(struct scm_request * scmrq)125 static void scm_request_done(struct scm_request *scmrq)
126 {
127 unsigned long flags;
128 struct msb *msb;
129 u64 aidaw;
130 int i;
131
132 for (i = 0; i < nr_requests_per_io && scmrq->request[i]; i++) {
133 msb = &scmrq->aob->msb[i];
134 aidaw = (u64)dma64_to_virt(msb->data_addr);
135
136 if ((msb->flags & MSB_FLAG_IDA) && aidaw &&
137 IS_ALIGNED(aidaw, PAGE_SIZE))
138 mempool_free(virt_to_page((void *)aidaw), aidaw_pool);
139 }
140
141 spin_lock_irqsave(&list_lock, flags);
142 list_add(&scmrq->list, &inactive_requests);
143 spin_unlock_irqrestore(&list_lock, flags);
144 }
145
scm_permit_request(struct scm_blk_dev * bdev,struct request * req)146 static bool scm_permit_request(struct scm_blk_dev *bdev, struct request *req)
147 {
148 return rq_data_dir(req) != WRITE || bdev->state != SCM_WR_PROHIBIT;
149 }
150
scm_aidaw_alloc(void)151 static inline struct aidaw *scm_aidaw_alloc(void)
152 {
153 struct page *page = mempool_alloc(aidaw_pool, GFP_ATOMIC);
154
155 return page ? page_address(page) : NULL;
156 }
157
scm_aidaw_bytes(struct aidaw * aidaw)158 static inline unsigned long scm_aidaw_bytes(struct aidaw *aidaw)
159 {
160 unsigned long _aidaw = (unsigned long) aidaw;
161 unsigned long bytes = ALIGN(_aidaw, PAGE_SIZE) - _aidaw;
162
163 return (bytes / sizeof(*aidaw)) * PAGE_SIZE;
164 }
165
scm_aidaw_fetch(struct scm_request * scmrq,unsigned int bytes)166 struct aidaw *scm_aidaw_fetch(struct scm_request *scmrq, unsigned int bytes)
167 {
168 struct aidaw *aidaw;
169
170 if (scm_aidaw_bytes(scmrq->next_aidaw) >= bytes)
171 return scmrq->next_aidaw;
172
173 aidaw = scm_aidaw_alloc();
174 if (aidaw)
175 memset(aidaw, 0, PAGE_SIZE);
176 return aidaw;
177 }
178
scm_request_prepare(struct scm_request * scmrq)179 static int scm_request_prepare(struct scm_request *scmrq)
180 {
181 struct scm_blk_dev *bdev = scmrq->bdev;
182 struct scm_device *scmdev = bdev->gendisk->private_data;
183 int pos = scmrq->aob->request.msb_count;
184 struct msb *msb = &scmrq->aob->msb[pos];
185 struct request *req = scmrq->request[pos];
186 struct req_iterator iter;
187 struct aidaw *aidaw;
188 struct bio_vec bv;
189
190 aidaw = scm_aidaw_fetch(scmrq, blk_rq_bytes(req));
191 if (!aidaw)
192 return -ENOMEM;
193
194 msb->bs = MSB_BS_4K;
195 scmrq->aob->request.msb_count++;
196 msb->scm_addr = scmdev->address + ((u64) blk_rq_pos(req) << 9);
197 msb->oc = (rq_data_dir(req) == READ) ? MSB_OC_READ : MSB_OC_WRITE;
198 msb->flags |= MSB_FLAG_IDA;
199 msb->data_addr = virt_to_dma64(aidaw);
200
201 rq_for_each_segment(bv, req, iter) {
202 WARN_ON(bv.bv_offset);
203 msb->blk_count += bv.bv_len >> 12;
204 aidaw->data_addr = virt_to_dma64(page_address(bv.bv_page));
205 aidaw++;
206 }
207
208 scmrq->next_aidaw = aidaw;
209 return 0;
210 }
211
scm_request_set(struct scm_request * scmrq,struct request * req)212 static inline void scm_request_set(struct scm_request *scmrq,
213 struct request *req)
214 {
215 scmrq->request[scmrq->aob->request.msb_count] = req;
216 }
217
scm_request_init(struct scm_blk_dev * bdev,struct scm_request * scmrq)218 static inline void scm_request_init(struct scm_blk_dev *bdev,
219 struct scm_request *scmrq)
220 {
221 struct aob_rq_header *aobrq = to_aobrq(scmrq);
222 struct aob *aob = scmrq->aob;
223
224 memset(scmrq->request, 0,
225 nr_requests_per_io * sizeof(scmrq->request[0]));
226 memset(aob, 0, sizeof(*aob));
227 aobrq->scmdev = bdev->scmdev;
228 aob->request.cmd_code = ARQB_CMD_MOVE;
229 aob->request.data = (u64) aobrq;
230 scmrq->bdev = bdev;
231 scmrq->retries = 4;
232 scmrq->error = BLK_STS_OK;
233 /* We don't use all msbs - place aidaws at the end of the aob page. */
234 scmrq->next_aidaw = (void *) &aob->msb[nr_requests_per_io];
235 }
236
scm_request_requeue(struct scm_request * scmrq)237 static void scm_request_requeue(struct scm_request *scmrq)
238 {
239 struct scm_blk_dev *bdev = scmrq->bdev;
240 int i;
241
242 for (i = 0; i < nr_requests_per_io && scmrq->request[i]; i++)
243 blk_mq_requeue_request(scmrq->request[i], false);
244
245 atomic_dec(&bdev->queued_reqs);
246 scm_request_done(scmrq);
247 blk_mq_kick_requeue_list(bdev->rq);
248 }
249
scm_request_finish(struct scm_request * scmrq)250 static void scm_request_finish(struct scm_request *scmrq)
251 {
252 struct scm_blk_dev *bdev = scmrq->bdev;
253 blk_status_t *error;
254 int i;
255
256 for (i = 0; i < nr_requests_per_io && scmrq->request[i]; i++) {
257 error = blk_mq_rq_to_pdu(scmrq->request[i]);
258 *error = scmrq->error;
259 if (likely(!blk_should_fake_timeout(scmrq->request[i]->q)))
260 blk_mq_complete_request(scmrq->request[i]);
261 }
262
263 atomic_dec(&bdev->queued_reqs);
264 scm_request_done(scmrq);
265 }
266
scm_request_start(struct scm_request * scmrq)267 static void scm_request_start(struct scm_request *scmrq)
268 {
269 struct scm_blk_dev *bdev = scmrq->bdev;
270
271 atomic_inc(&bdev->queued_reqs);
272 if (eadm_start_aob(scmrq->aob)) {
273 SCM_LOG(5, "no subchannel");
274 scm_request_requeue(scmrq);
275 }
276 }
277
278 struct scm_queue {
279 struct scm_request *scmrq;
280 spinlock_t lock;
281 };
282
scm_blk_request(struct blk_mq_hw_ctx * hctx,const struct blk_mq_queue_data * qd)283 static blk_status_t scm_blk_request(struct blk_mq_hw_ctx *hctx,
284 const struct blk_mq_queue_data *qd)
285 {
286 struct scm_device *scmdev = hctx->queue->queuedata;
287 struct scm_blk_dev *bdev = dev_get_drvdata(&scmdev->dev);
288 struct scm_queue *sq = hctx->driver_data;
289 struct request *req = qd->rq;
290 struct scm_request *scmrq;
291
292 spin_lock(&sq->lock);
293 if (!scm_permit_request(bdev, req)) {
294 spin_unlock(&sq->lock);
295 return BLK_STS_RESOURCE;
296 }
297
298 scmrq = sq->scmrq;
299 if (!scmrq) {
300 scmrq = scm_request_fetch();
301 if (!scmrq) {
302 SCM_LOG(5, "no request");
303 spin_unlock(&sq->lock);
304 return BLK_STS_RESOURCE;
305 }
306 scm_request_init(bdev, scmrq);
307 sq->scmrq = scmrq;
308 }
309 scm_request_set(scmrq, req);
310
311 if (scm_request_prepare(scmrq)) {
312 SCM_LOG(5, "aidaw alloc failed");
313 scm_request_set(scmrq, NULL);
314
315 if (scmrq->aob->request.msb_count)
316 scm_request_start(scmrq);
317
318 sq->scmrq = NULL;
319 spin_unlock(&sq->lock);
320 return BLK_STS_RESOURCE;
321 }
322 blk_mq_start_request(req);
323
324 if (qd->last || scmrq->aob->request.msb_count == nr_requests_per_io) {
325 scm_request_start(scmrq);
326 sq->scmrq = NULL;
327 }
328 spin_unlock(&sq->lock);
329 return BLK_STS_OK;
330 }
331
scm_blk_init_hctx(struct blk_mq_hw_ctx * hctx,void * data,unsigned int idx)332 static int scm_blk_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
333 unsigned int idx)
334 {
335 struct scm_queue *qd = kzalloc(sizeof(*qd), GFP_KERNEL);
336
337 if (!qd)
338 return -ENOMEM;
339
340 spin_lock_init(&qd->lock);
341 hctx->driver_data = qd;
342
343 return 0;
344 }
345
scm_blk_exit_hctx(struct blk_mq_hw_ctx * hctx,unsigned int idx)346 static void scm_blk_exit_hctx(struct blk_mq_hw_ctx *hctx, unsigned int idx)
347 {
348 struct scm_queue *qd = hctx->driver_data;
349
350 WARN_ON(qd->scmrq);
351 kfree(hctx->driver_data);
352 hctx->driver_data = NULL;
353 }
354
__scmrq_log_error(struct scm_request * scmrq)355 static void __scmrq_log_error(struct scm_request *scmrq)
356 {
357 struct aob *aob = scmrq->aob;
358
359 if (scmrq->error == BLK_STS_TIMEOUT)
360 SCM_LOG(1, "Request timeout");
361 else {
362 SCM_LOG(1, "Request error");
363 SCM_LOG_HEX(1, &aob->response, sizeof(aob->response));
364 }
365 if (scmrq->retries)
366 SCM_LOG(1, "Retry request");
367 else
368 pr_err("An I/O operation to SCM failed with rc=%d\n",
369 scmrq->error);
370 }
371
scm_blk_handle_error(struct scm_request * scmrq)372 static void scm_blk_handle_error(struct scm_request *scmrq)
373 {
374 struct scm_blk_dev *bdev = scmrq->bdev;
375 unsigned long flags;
376
377 if (scmrq->error != BLK_STS_IOERR)
378 goto restart;
379
380 /* For -EIO the response block is valid. */
381 switch (scmrq->aob->response.eqc) {
382 case EQC_WR_PROHIBIT:
383 spin_lock_irqsave(&bdev->lock, flags);
384 if (bdev->state != SCM_WR_PROHIBIT)
385 pr_info("%lx: Write access to the SCM increment is suspended\n",
386 (unsigned long) bdev->scmdev->address);
387 bdev->state = SCM_WR_PROHIBIT;
388 spin_unlock_irqrestore(&bdev->lock, flags);
389 goto requeue;
390 default:
391 break;
392 }
393
394 restart:
395 if (!eadm_start_aob(scmrq->aob))
396 return;
397
398 requeue:
399 scm_request_requeue(scmrq);
400 }
401
scm_blk_irq(struct scm_device * scmdev,void * data,blk_status_t error)402 void scm_blk_irq(struct scm_device *scmdev, void *data, blk_status_t error)
403 {
404 struct scm_request *scmrq = data;
405
406 scmrq->error = error;
407 if (error) {
408 __scmrq_log_error(scmrq);
409 if (scmrq->retries-- > 0) {
410 scm_blk_handle_error(scmrq);
411 return;
412 }
413 }
414
415 scm_request_finish(scmrq);
416 }
417
scm_blk_request_done(struct request * req)418 static void scm_blk_request_done(struct request *req)
419 {
420 blk_status_t *error = blk_mq_rq_to_pdu(req);
421
422 blk_mq_end_request(req, *error);
423 }
424
425 static const struct block_device_operations scm_blk_devops = {
426 .owner = THIS_MODULE,
427 };
428
429 static const struct blk_mq_ops scm_mq_ops = {
430 .queue_rq = scm_blk_request,
431 .complete = scm_blk_request_done,
432 .init_hctx = scm_blk_init_hctx,
433 .exit_hctx = scm_blk_exit_hctx,
434 };
435
scm_blk_dev_setup(struct scm_blk_dev * bdev,struct scm_device * scmdev)436 int scm_blk_dev_setup(struct scm_blk_dev *bdev, struct scm_device *scmdev)
437 {
438 struct queue_limits lim = {
439 .logical_block_size = 1 << 12,
440 };
441 unsigned int devindex;
442 int len, ret;
443
444 lim.max_segments = min(scmdev->nr_max_block,
445 (unsigned int) (PAGE_SIZE / sizeof(struct aidaw)));
446 lim.max_hw_sectors = lim.max_segments << 3; /* 8 * 512 = blk_size */
447
448 devindex = atomic_inc_return(&nr_devices) - 1;
449 /* scma..scmz + scmaa..scmzz */
450 if (devindex > 701) {
451 ret = -ENODEV;
452 goto out;
453 }
454
455 bdev->scmdev = scmdev;
456 bdev->state = SCM_OPER;
457 spin_lock_init(&bdev->lock);
458 atomic_set(&bdev->queued_reqs, 0);
459
460 bdev->tag_set.ops = &scm_mq_ops;
461 bdev->tag_set.cmd_size = sizeof(blk_status_t);
462 bdev->tag_set.nr_hw_queues = nr_requests;
463 bdev->tag_set.queue_depth = nr_requests_per_io * nr_requests;
464 bdev->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
465 bdev->tag_set.numa_node = NUMA_NO_NODE;
466
467 ret = blk_mq_alloc_tag_set(&bdev->tag_set);
468 if (ret)
469 goto out;
470
471 bdev->gendisk = blk_mq_alloc_disk(&bdev->tag_set, &lim, scmdev);
472 if (IS_ERR(bdev->gendisk)) {
473 ret = PTR_ERR(bdev->gendisk);
474 goto out_tag;
475 }
476 bdev->gendisk->private_data = scmdev;
477 bdev->gendisk->fops = &scm_blk_devops;
478 bdev->gendisk->major = scm_major;
479 bdev->gendisk->first_minor = devindex * SCM_NR_PARTS;
480 bdev->gendisk->minors = SCM_NR_PARTS;
481
482 len = snprintf(bdev->gendisk->disk_name, DISK_NAME_LEN, "scm");
483 if (devindex > 25) {
484 len += snprintf(bdev->gendisk->disk_name + len,
485 DISK_NAME_LEN - len, "%c",
486 'a' + (devindex / 26) - 1);
487 devindex = devindex % 26;
488 }
489 snprintf(bdev->gendisk->disk_name + len, DISK_NAME_LEN - len, "%c",
490 'a' + devindex);
491
492 /* 512 byte sectors */
493 set_capacity(bdev->gendisk, scmdev->size >> 9);
494 ret = device_add_disk(&scmdev->dev, bdev->gendisk, NULL);
495 if (ret)
496 goto out_cleanup_disk;
497
498 return 0;
499
500 out_cleanup_disk:
501 put_disk(bdev->gendisk);
502 out_tag:
503 blk_mq_free_tag_set(&bdev->tag_set);
504 out:
505 atomic_dec(&nr_devices);
506 return ret;
507 }
508
scm_blk_dev_cleanup(struct scm_blk_dev * bdev)509 void scm_blk_dev_cleanup(struct scm_blk_dev *bdev)
510 {
511 del_gendisk(bdev->gendisk);
512 put_disk(bdev->gendisk);
513 blk_mq_free_tag_set(&bdev->tag_set);
514 }
515
scm_blk_set_available(struct scm_blk_dev * bdev)516 void scm_blk_set_available(struct scm_blk_dev *bdev)
517 {
518 unsigned long flags;
519
520 spin_lock_irqsave(&bdev->lock, flags);
521 if (bdev->state == SCM_WR_PROHIBIT)
522 pr_info("%lx: Write access to the SCM increment is restored\n",
523 (unsigned long) bdev->scmdev->address);
524 bdev->state = SCM_OPER;
525 spin_unlock_irqrestore(&bdev->lock, flags);
526 }
527
scm_blk_params_valid(void)528 static bool __init scm_blk_params_valid(void)
529 {
530 if (!nr_requests_per_io || nr_requests_per_io > 64)
531 return false;
532
533 return true;
534 }
535
scm_blk_init(void)536 static int __init scm_blk_init(void)
537 {
538 int ret = -EINVAL;
539
540 if (!scm_blk_params_valid())
541 goto out;
542
543 ret = register_blkdev(0, "scm");
544 if (ret < 0)
545 goto out;
546
547 scm_major = ret;
548 ret = scm_alloc_rqs(nr_requests);
549 if (ret)
550 goto out_free;
551
552 scm_debug = debug_register("scm_log", 16, 1, 16);
553 if (!scm_debug) {
554 ret = -ENOMEM;
555 goto out_free;
556 }
557
558 debug_register_view(scm_debug, &debug_hex_ascii_view);
559 debug_set_level(scm_debug, 2);
560
561 ret = scm_drv_init();
562 if (ret)
563 goto out_dbf;
564
565 return ret;
566
567 out_dbf:
568 debug_unregister(scm_debug);
569 out_free:
570 scm_free_rqs();
571 unregister_blkdev(scm_major, "scm");
572 out:
573 return ret;
574 }
575 module_init(scm_blk_init);
576
scm_blk_cleanup(void)577 static void __exit scm_blk_cleanup(void)
578 {
579 scm_drv_cleanup();
580 debug_unregister(scm_debug);
581 scm_free_rqs();
582 unregister_blkdev(scm_major, "scm");
583 }
584 module_exit(scm_blk_cleanup);
585