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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 <asm/eadm.h>
21#include "scm_blk.h"
22
23debug_info_t *scm_debug;
24static int scm_major;
25static mempool_t *aidaw_pool;
26static DEFINE_SPINLOCK(list_lock);
27static LIST_HEAD(inactive_requests);
28static unsigned int nr_requests = 64;
29static unsigned int nr_requests_per_io = 8;
30static atomic_t nr_devices = ATOMIC_INIT(0);
31module_param(nr_requests, uint, S_IRUGO);
32MODULE_PARM_DESC(nr_requests, "Number of parallel requests.");
33
34module_param(nr_requests_per_io, uint, S_IRUGO);
35MODULE_PARM_DESC(nr_requests_per_io, "Number of requests per IO.");
36
37MODULE_DESCRIPTION("Block driver for s390 storage class memory.");
38MODULE_LICENSE("GPL");
39MODULE_ALIAS("scm:scmdev*");
40
41static void __scm_free_rq(struct scm_request *scmrq)
42{
43 struct aob_rq_header *aobrq = to_aobrq(scmrq);
44
45 free_page((unsigned long) scmrq->aob);
46 kfree(scmrq->request);
47 kfree(aobrq);
48}
49
50static void scm_free_rqs(void)
51{
52 struct list_head *iter, *safe;
53 struct scm_request *scmrq;
54
55 spin_lock_irq(&list_lock);
56 list_for_each_safe(iter, safe, &inactive_requests) {
57 scmrq = list_entry(iter, struct scm_request, list);
58 list_del(&scmrq->list);
59 __scm_free_rq(scmrq);
60 }
61 spin_unlock_irq(&list_lock);
62
63 mempool_destroy(aidaw_pool);
64}
65
66static int __scm_alloc_rq(void)
67{
68 struct aob_rq_header *aobrq;
69 struct scm_request *scmrq;
70
71 aobrq = kzalloc(sizeof(*aobrq) + sizeof(*scmrq), GFP_KERNEL);
72 if (!aobrq)
73 return -ENOMEM;
74
75 scmrq = (void *) aobrq->data;
76 scmrq->aob = (void *) get_zeroed_page(GFP_DMA);
77 if (!scmrq->aob)
78 goto free;
79
80 scmrq->request = kcalloc(nr_requests_per_io, sizeof(scmrq->request[0]),
81 GFP_KERNEL);
82 if (!scmrq->request)
83 goto free;
84
85 INIT_LIST_HEAD(&scmrq->list);
86 spin_lock_irq(&list_lock);
87 list_add(&scmrq->list, &inactive_requests);
88 spin_unlock_irq(&list_lock);
89
90 return 0;
91free:
92 __scm_free_rq(scmrq);
93 return -ENOMEM;
94}
95
96static int scm_alloc_rqs(unsigned int nrqs)
97{
98 int ret = 0;
99
100 aidaw_pool = mempool_create_page_pool(max(nrqs/8, 1U), 0);
101 if (!aidaw_pool)
102 return -ENOMEM;
103
104 while (nrqs-- && !ret)
105 ret = __scm_alloc_rq();
106
107 return ret;
108}
109
110static struct scm_request *scm_request_fetch(void)
111{
112 struct scm_request *scmrq = NULL;
113
114 spin_lock_irq(&list_lock);
115 if (list_empty(&inactive_requests))
116 goto out;
117 scmrq = list_first_entry(&inactive_requests, struct scm_request, list);
118 list_del(&scmrq->list);
119out:
120 spin_unlock_irq(&list_lock);
121 return scmrq;
122}
123
124static void scm_request_done(struct scm_request *scmrq)
125{
126 unsigned long flags;
127 struct msb *msb;
128 u64 aidaw;
129 int i;
130
131 for (i = 0; i < nr_requests_per_io && scmrq->request[i]; i++) {
132 msb = &scmrq->aob->msb[i];
133 aidaw = msb->data_addr;
134
135 if ((msb->flags & MSB_FLAG_IDA) && aidaw &&
136 IS_ALIGNED(aidaw, PAGE_SIZE))
137 mempool_free(virt_to_page(aidaw), aidaw_pool);
138 }
139
140 spin_lock_irqsave(&list_lock, flags);
141 list_add(&scmrq->list, &inactive_requests);
142 spin_unlock_irqrestore(&list_lock, flags);
143}
144
145static bool scm_permit_request(struct scm_blk_dev *bdev, struct request *req)
146{
147 return rq_data_dir(req) != WRITE || bdev->state != SCM_WR_PROHIBIT;
148}
149
150static inline struct aidaw *scm_aidaw_alloc(void)
151{
152 struct page *page = mempool_alloc(aidaw_pool, GFP_ATOMIC);
153
154 return page ? page_address(page) : NULL;
155}
156
157static inline unsigned long scm_aidaw_bytes(struct aidaw *aidaw)
158{
159 unsigned long _aidaw = (unsigned long) aidaw;
160 unsigned long bytes = ALIGN(_aidaw, PAGE_SIZE) - _aidaw;
161
162 return (bytes / sizeof(*aidaw)) * PAGE_SIZE;
163}
164
165struct aidaw *scm_aidaw_fetch(struct scm_request *scmrq, unsigned int bytes)
166{
167 struct aidaw *aidaw;
168
169 if (scm_aidaw_bytes(scmrq->next_aidaw) >= bytes)
170 return scmrq->next_aidaw;
171
172 aidaw = scm_aidaw_alloc();
173 if (aidaw)
174 memset(aidaw, 0, PAGE_SIZE);
175 return aidaw;
176}
177
178static int scm_request_prepare(struct scm_request *scmrq)
179{
180 struct scm_blk_dev *bdev = scmrq->bdev;
181 struct scm_device *scmdev = bdev->gendisk->private_data;
182 int pos = scmrq->aob->request.msb_count;
183 struct msb *msb = &scmrq->aob->msb[pos];
184 struct request *req = scmrq->request[pos];
185 struct req_iterator iter;
186 struct aidaw *aidaw;
187 struct bio_vec bv;
188
189 aidaw = scm_aidaw_fetch(scmrq, blk_rq_bytes(req));
190 if (!aidaw)
191 return -ENOMEM;
192
193 msb->bs = MSB_BS_4K;
194 scmrq->aob->request.msb_count++;
195 msb->scm_addr = scmdev->address + ((u64) blk_rq_pos(req) << 9);
196 msb->oc = (rq_data_dir(req) == READ) ? MSB_OC_READ : MSB_OC_WRITE;
197 msb->flags |= MSB_FLAG_IDA;
198 msb->data_addr = (u64) aidaw;
199
200 rq_for_each_segment(bv, req, iter) {
201 WARN_ON(bv.bv_offset);
202 msb->blk_count += bv.bv_len >> 12;
203 aidaw->data_addr = (u64) page_address(bv.bv_page);
204 aidaw++;
205 }
206
207 scmrq->next_aidaw = aidaw;
208 return 0;
209}
210
211static inline void scm_request_set(struct scm_request *scmrq,
212 struct request *req)
213{
214 scmrq->request[scmrq->aob->request.msb_count] = req;
215}
216
217static inline void scm_request_init(struct scm_blk_dev *bdev,
218 struct scm_request *scmrq)
219{
220 struct aob_rq_header *aobrq = to_aobrq(scmrq);
221 struct aob *aob = scmrq->aob;
222
223 memset(scmrq->request, 0,
224 nr_requests_per_io * sizeof(scmrq->request[0]));
225 memset(aob, 0, sizeof(*aob));
226 aobrq->scmdev = bdev->scmdev;
227 aob->request.cmd_code = ARQB_CMD_MOVE;
228 aob->request.data = (u64) aobrq;
229 scmrq->bdev = bdev;
230 scmrq->retries = 4;
231 scmrq->error = BLK_STS_OK;
232
233 scmrq->next_aidaw = (void *) &aob->msb[nr_requests_per_io];
234}
235
236static void scm_request_requeue(struct scm_request *scmrq)
237{
238 struct scm_blk_dev *bdev = scmrq->bdev;
239 int i;
240
241 for (i = 0; i < nr_requests_per_io && scmrq->request[i]; i++)
242 blk_mq_requeue_request(scmrq->request[i], false);
243
244 atomic_dec(&bdev->queued_reqs);
245 scm_request_done(scmrq);
246 blk_mq_kick_requeue_list(bdev->rq);
247}
248
249static void scm_request_finish(struct scm_request *scmrq)
250{
251 struct scm_blk_dev *bdev = scmrq->bdev;
252 blk_status_t *error;
253 int i;
254
255 for (i = 0; i < nr_requests_per_io && scmrq->request[i]; i++) {
256 error = blk_mq_rq_to_pdu(scmrq->request[i]);
257 *error = scmrq->error;
258 if (likely(!blk_should_fake_timeout(scmrq->request[i]->q)))
259 blk_mq_complete_request(scmrq->request[i]);
260 }
261
262 atomic_dec(&bdev->queued_reqs);
263 scm_request_done(scmrq);
264}
265
266static void scm_request_start(struct scm_request *scmrq)
267{
268 struct scm_blk_dev *bdev = scmrq->bdev;
269
270 atomic_inc(&bdev->queued_reqs);
271 if (eadm_start_aob(scmrq->aob)) {
272 SCM_LOG(5, "no subchannel");
273 scm_request_requeue(scmrq);
274 }
275}
276
277struct scm_queue {
278 struct scm_request *scmrq;
279 spinlock_t lock;
280};
281
282static blk_status_t scm_blk_request(struct blk_mq_hw_ctx *hctx,
283 const struct blk_mq_queue_data *qd)
284{
285 struct scm_device *scmdev = hctx->queue->queuedata;
286 struct scm_blk_dev *bdev = dev_get_drvdata(&scmdev->dev);
287 struct scm_queue *sq = hctx->driver_data;
288 struct request *req = qd->rq;
289 struct scm_request *scmrq;
290
291 spin_lock(&sq->lock);
292 if (!scm_permit_request(bdev, req)) {
293 spin_unlock(&sq->lock);
294 return BLK_STS_RESOURCE;
295 }
296
297 scmrq = sq->scmrq;
298 if (!scmrq) {
299 scmrq = scm_request_fetch();
300 if (!scmrq) {
301 SCM_LOG(5, "no request");
302 spin_unlock(&sq->lock);
303 return BLK_STS_RESOURCE;
304 }
305 scm_request_init(bdev, scmrq);
306 sq->scmrq = scmrq;
307 }
308 scm_request_set(scmrq, req);
309
310 if (scm_request_prepare(scmrq)) {
311 SCM_LOG(5, "aidaw alloc failed");
312 scm_request_set(scmrq, NULL);
313
314 if (scmrq->aob->request.msb_count)
315 scm_request_start(scmrq);
316
317 sq->scmrq = NULL;
318 spin_unlock(&sq->lock);
319 return BLK_STS_RESOURCE;
320 }
321 blk_mq_start_request(req);
322
323 if (qd->last || scmrq->aob->request.msb_count == nr_requests_per_io) {
324 scm_request_start(scmrq);
325 sq->scmrq = NULL;
326 }
327 spin_unlock(&sq->lock);
328 return BLK_STS_OK;
329}
330
331static int scm_blk_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
332 unsigned int idx)
333{
334 struct scm_queue *qd = kzalloc(sizeof(*qd), GFP_KERNEL);
335
336 if (!qd)
337 return -ENOMEM;
338
339 spin_lock_init(&qd->lock);
340 hctx->driver_data = qd;
341
342 return 0;
343}
344
345static void scm_blk_exit_hctx(struct blk_mq_hw_ctx *hctx, unsigned int idx)
346{
347 struct scm_queue *qd = hctx->driver_data;
348
349 WARN_ON(qd->scmrq);
350 kfree(hctx->driver_data);
351 hctx->driver_data = NULL;
352}
353
354static void __scmrq_log_error(struct scm_request *scmrq)
355{
356 struct aob *aob = scmrq->aob;
357
358 if (scmrq->error == BLK_STS_TIMEOUT)
359 SCM_LOG(1, "Request timeout");
360 else {
361 SCM_LOG(1, "Request error");
362 SCM_LOG_HEX(1, &aob->response, sizeof(aob->response));
363 }
364 if (scmrq->retries)
365 SCM_LOG(1, "Retry request");
366 else
367 pr_err("An I/O operation to SCM failed with rc=%d\n",
368 scmrq->error);
369}
370
371static void scm_blk_handle_error(struct scm_request *scmrq)
372{
373 struct scm_blk_dev *bdev = scmrq->bdev;
374 unsigned long flags;
375
376 if (scmrq->error != BLK_STS_IOERR)
377 goto restart;
378
379
380 switch (scmrq->aob->response.eqc) {
381 case EQC_WR_PROHIBIT:
382 spin_lock_irqsave(&bdev->lock, flags);
383 if (bdev->state != SCM_WR_PROHIBIT)
384 pr_info("%lx: Write access to the SCM increment is suspended\n",
385 (unsigned long) bdev->scmdev->address);
386 bdev->state = SCM_WR_PROHIBIT;
387 spin_unlock_irqrestore(&bdev->lock, flags);
388 goto requeue;
389 default:
390 break;
391 }
392
393restart:
394 if (!eadm_start_aob(scmrq->aob))
395 return;
396
397requeue:
398 scm_request_requeue(scmrq);
399}
400
401void scm_blk_irq(struct scm_device *scmdev, void *data, blk_status_t error)
402{
403 struct scm_request *scmrq = data;
404
405 scmrq->error = error;
406 if (error) {
407 __scmrq_log_error(scmrq);
408 if (scmrq->retries-- > 0) {
409 scm_blk_handle_error(scmrq);
410 return;
411 }
412 }
413
414 scm_request_finish(scmrq);
415}
416
417static void scm_blk_request_done(struct request *req)
418{
419 blk_status_t *error = blk_mq_rq_to_pdu(req);
420
421 blk_mq_end_request(req, *error);
422}
423
424static const struct block_device_operations scm_blk_devops = {
425 .owner = THIS_MODULE,
426};
427
428static const struct blk_mq_ops scm_mq_ops = {
429 .queue_rq = scm_blk_request,
430 .complete = scm_blk_request_done,
431 .init_hctx = scm_blk_init_hctx,
432 .exit_hctx = scm_blk_exit_hctx,
433};
434
435int scm_blk_dev_setup(struct scm_blk_dev *bdev, struct scm_device *scmdev)
436{
437 unsigned int devindex, nr_max_blk;
438 struct request_queue *rq;
439 int len, ret;
440
441 devindex = atomic_inc_return(&nr_devices) - 1;
442
443 if (devindex > 701) {
444 ret = -ENODEV;
445 goto out;
446 }
447
448 bdev->scmdev = scmdev;
449 bdev->state = SCM_OPER;
450 spin_lock_init(&bdev->lock);
451 atomic_set(&bdev->queued_reqs, 0);
452
453 bdev->tag_set.ops = &scm_mq_ops;
454 bdev->tag_set.cmd_size = sizeof(blk_status_t);
455 bdev->tag_set.nr_hw_queues = nr_requests;
456 bdev->tag_set.queue_depth = nr_requests_per_io * nr_requests;
457 bdev->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
458 bdev->tag_set.numa_node = NUMA_NO_NODE;
459
460 ret = blk_mq_alloc_tag_set(&bdev->tag_set);
461 if (ret)
462 goto out;
463
464 bdev->gendisk = blk_mq_alloc_disk(&bdev->tag_set, scmdev);
465 if (IS_ERR(bdev->gendisk)) {
466 ret = PTR_ERR(bdev->gendisk);
467 goto out_tag;
468 }
469 rq = bdev->rq = bdev->gendisk->queue;
470 nr_max_blk = min(scmdev->nr_max_block,
471 (unsigned int) (PAGE_SIZE / sizeof(struct aidaw)));
472
473 blk_queue_logical_block_size(rq, 1 << 12);
474 blk_queue_max_hw_sectors(rq, nr_max_blk << 3);
475 blk_queue_max_segments(rq, nr_max_blk);
476 blk_queue_flag_set(QUEUE_FLAG_NONROT, rq);
477 blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, rq);
478
479 bdev->gendisk->private_data = scmdev;
480 bdev->gendisk->fops = &scm_blk_devops;
481 bdev->gendisk->major = scm_major;
482 bdev->gendisk->first_minor = devindex * SCM_NR_PARTS;
483 bdev->gendisk->minors = SCM_NR_PARTS;
484
485 len = snprintf(bdev->gendisk->disk_name, DISK_NAME_LEN, "scm");
486 if (devindex > 25) {
487 len += snprintf(bdev->gendisk->disk_name + len,
488 DISK_NAME_LEN - len, "%c",
489 'a' + (devindex / 26) - 1);
490 devindex = devindex % 26;
491 }
492 snprintf(bdev->gendisk->disk_name + len, DISK_NAME_LEN - len, "%c",
493 'a' + devindex);
494
495
496 set_capacity(bdev->gendisk, scmdev->size >> 9);
497 ret = device_add_disk(&scmdev->dev, bdev->gendisk, NULL);
498 if (ret)
499 goto out_cleanup_disk;
500
501 return 0;
502
503out_cleanup_disk:
504 blk_cleanup_disk(bdev->gendisk);
505out_tag:
506 blk_mq_free_tag_set(&bdev->tag_set);
507out:
508 atomic_dec(&nr_devices);
509 return ret;
510}
511
512void scm_blk_dev_cleanup(struct scm_blk_dev *bdev)
513{
514 del_gendisk(bdev->gendisk);
515 blk_cleanup_disk(bdev->gendisk);
516 blk_mq_free_tag_set(&bdev->tag_set);
517}
518
519void scm_blk_set_available(struct scm_blk_dev *bdev)
520{
521 unsigned long flags;
522
523 spin_lock_irqsave(&bdev->lock, flags);
524 if (bdev->state == SCM_WR_PROHIBIT)
525 pr_info("%lx: Write access to the SCM increment is restored\n",
526 (unsigned long) bdev->scmdev->address);
527 bdev->state = SCM_OPER;
528 spin_unlock_irqrestore(&bdev->lock, flags);
529}
530
531static bool __init scm_blk_params_valid(void)
532{
533 if (!nr_requests_per_io || nr_requests_per_io > 64)
534 return false;
535
536 return true;
537}
538
539static int __init scm_blk_init(void)
540{
541 int ret = -EINVAL;
542
543 if (!scm_blk_params_valid())
544 goto out;
545
546 ret = register_blkdev(0, "scm");
547 if (ret < 0)
548 goto out;
549
550 scm_major = ret;
551 ret = scm_alloc_rqs(nr_requests);
552 if (ret)
553 goto out_free;
554
555 scm_debug = debug_register("scm_log", 16, 1, 16);
556 if (!scm_debug) {
557 ret = -ENOMEM;
558 goto out_free;
559 }
560
561 debug_register_view(scm_debug, &debug_hex_ascii_view);
562 debug_set_level(scm_debug, 2);
563
564 ret = scm_drv_init();
565 if (ret)
566 goto out_dbf;
567
568 return ret;
569
570out_dbf:
571 debug_unregister(scm_debug);
572out_free:
573 scm_free_rqs();
574 unregister_blkdev(scm_major, "scm");
575out:
576 return ret;
577}
578module_init(scm_blk_init);
579
580static void __exit scm_blk_cleanup(void)
581{
582 scm_drv_cleanup();
583 debug_unregister(scm_debug);
584 scm_free_rqs();
585 unregister_blkdev(scm_major, "scm");
586}
587module_exit(scm_blk_cleanup);
588
