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/genhd.h>
19 #include <linux/slab.h>
20 #include <linux/list.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 = msb->data_addr;
135 
136 		if ((msb->flags & MSB_FLAG_IDA) && aidaw &&
137 		    IS_ALIGNED(aidaw, PAGE_SIZE))
138 			mempool_free(virt_to_page(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 = (u64) 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 = (u64) 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 		blk_mq_complete_request(scmrq->request[i]);
260 	}
261 
262 	atomic_dec(&bdev->queued_reqs);
263 	scm_request_done(scmrq);
264 }
265 
scm_request_start(struct scm_request * scmrq)266 static 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 
277 struct scm_queue {
278 	struct scm_request *scmrq;
279 	spinlock_t lock;
280 };
281 
scm_blk_request(struct blk_mq_hw_ctx * hctx,const struct blk_mq_queue_data * qd)282 static 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 
scm_blk_init_hctx(struct blk_mq_hw_ctx * hctx,void * data,unsigned int idx)331 static 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 
scm_blk_exit_hctx(struct blk_mq_hw_ctx * hctx,unsigned int idx)345 static 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 
__scmrq_log_error(struct scm_request * scmrq)354 static 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 
scm_blk_handle_error(struct scm_request * scmrq)371 static 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 	/* For -EIO the response block is valid. */
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 
393 restart:
394 	if (!eadm_start_aob(scmrq->aob))
395 		return;
396 
397 requeue:
398 	scm_request_requeue(scmrq);
399 }
400 
scm_blk_irq(struct scm_device * scmdev,void * data,blk_status_t error)401 void 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 
scm_blk_request_done(struct request * req)417 static 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 
424 static const struct block_device_operations scm_blk_devops = {
425 	.owner = THIS_MODULE,
426 };
427 
428 static 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 
scm_blk_dev_setup(struct scm_blk_dev * bdev,struct scm_device * scmdev)435 int 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 	/* scma..scmz + scmaa..scmzz */
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 	rq = blk_mq_init_queue(&bdev->tag_set);
465 	if (IS_ERR(rq)) {
466 		ret = PTR_ERR(rq);
467 		goto out_tag;
468 	}
469 	bdev->rq = rq;
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); /* 8 * 512 = blk_size */
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 = alloc_disk(SCM_NR_PARTS);
480 	if (!bdev->gendisk) {
481 		ret = -ENOMEM;
482 		goto out_queue;
483 	}
484 	rq->queuedata = scmdev;
485 	bdev->gendisk->private_data = scmdev;
486 	bdev->gendisk->fops = &scm_blk_devops;
487 	bdev->gendisk->queue = rq;
488 	bdev->gendisk->major = scm_major;
489 	bdev->gendisk->first_minor = devindex * SCM_NR_PARTS;
490 
491 	len = snprintf(bdev->gendisk->disk_name, DISK_NAME_LEN, "scm");
492 	if (devindex > 25) {
493 		len += snprintf(bdev->gendisk->disk_name + len,
494 				DISK_NAME_LEN - len, "%c",
495 				'a' + (devindex / 26) - 1);
496 		devindex = devindex % 26;
497 	}
498 	snprintf(bdev->gendisk->disk_name + len, DISK_NAME_LEN - len, "%c",
499 		 'a' + devindex);
500 
501 	/* 512 byte sectors */
502 	set_capacity(bdev->gendisk, scmdev->size >> 9);
503 	device_add_disk(&scmdev->dev, bdev->gendisk, NULL);
504 	return 0;
505 
506 out_queue:
507 	blk_cleanup_queue(rq);
508 out_tag:
509 	blk_mq_free_tag_set(&bdev->tag_set);
510 out:
511 	atomic_dec(&nr_devices);
512 	return ret;
513 }
514 
scm_blk_dev_cleanup(struct scm_blk_dev * bdev)515 void scm_blk_dev_cleanup(struct scm_blk_dev *bdev)
516 {
517 	del_gendisk(bdev->gendisk);
518 	blk_cleanup_queue(bdev->gendisk->queue);
519 	blk_mq_free_tag_set(&bdev->tag_set);
520 	put_disk(bdev->gendisk);
521 }
522 
scm_blk_set_available(struct scm_blk_dev * bdev)523 void scm_blk_set_available(struct scm_blk_dev *bdev)
524 {
525 	unsigned long flags;
526 
527 	spin_lock_irqsave(&bdev->lock, flags);
528 	if (bdev->state == SCM_WR_PROHIBIT)
529 		pr_info("%lx: Write access to the SCM increment is restored\n",
530 			(unsigned long) bdev->scmdev->address);
531 	bdev->state = SCM_OPER;
532 	spin_unlock_irqrestore(&bdev->lock, flags);
533 }
534 
scm_blk_params_valid(void)535 static bool __init scm_blk_params_valid(void)
536 {
537 	if (!nr_requests_per_io || nr_requests_per_io > 64)
538 		return false;
539 
540 	return true;
541 }
542 
scm_blk_init(void)543 static int __init scm_blk_init(void)
544 {
545 	int ret = -EINVAL;
546 
547 	if (!scm_blk_params_valid())
548 		goto out;
549 
550 	ret = register_blkdev(0, "scm");
551 	if (ret < 0)
552 		goto out;
553 
554 	scm_major = ret;
555 	ret = scm_alloc_rqs(nr_requests);
556 	if (ret)
557 		goto out_free;
558 
559 	scm_debug = debug_register("scm_log", 16, 1, 16);
560 	if (!scm_debug) {
561 		ret = -ENOMEM;
562 		goto out_free;
563 	}
564 
565 	debug_register_view(scm_debug, &debug_hex_ascii_view);
566 	debug_set_level(scm_debug, 2);
567 
568 	ret = scm_drv_init();
569 	if (ret)
570 		goto out_dbf;
571 
572 	return ret;
573 
574 out_dbf:
575 	debug_unregister(scm_debug);
576 out_free:
577 	scm_free_rqs();
578 	unregister_blkdev(scm_major, "scm");
579 out:
580 	return ret;
581 }
582 module_init(scm_blk_init);
583 
scm_blk_cleanup(void)584 static void __exit scm_blk_cleanup(void)
585 {
586 	scm_drv_cleanup();
587 	debug_unregister(scm_debug);
588 	scm_free_rqs();
589 	unregister_blkdev(scm_major, "scm");
590 }
591 module_exit(scm_blk_cleanup);
592