xref: /linux/drivers/s390/block/scm_blk.c (revision a1ff5a7d78a036d6c2178ee5acd6ba4946243800)
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