sclp_mem.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Memory hotplug support via sclp
  4 *
  5 * Copyright IBM Corp. 2025
  6 */
  7
  8#define pr_fmt(fmt) "sclp_mem: " fmt
  9
 10#include <linux/cpufeature.h>
 11#include <linux/container_of.h>
 12#include <linux/err.h>
 13#include <linux/errno.h>
 14#include <linux/init.h>
 15#include <linux/kobject.h>
 16#include <linux/kstrtox.h>
 17#include <linux/memory.h>
 18#include <linux/memory_hotplug.h>
 19#include <linux/mm.h>
 20#include <linux/mmzone.h>
 21#include <linux/slab.h>
 22#include <asm/facility.h>
 23#include <asm/page.h>
 24#include <asm/page-states.h>
 25#include <asm/sclp.h>
 26
 27#include "sclp.h"
 28
 29#define SCLP_CMDW_ASSIGN_STORAGE		0x000d0001
 30#define SCLP_CMDW_UNASSIGN_STORAGE		0x000c0001
 31
 32static LIST_HEAD(sclp_mem_list);
 33static u8 sclp_max_storage_id;
 34static DECLARE_BITMAP(sclp_storage_ids, 256);
 35
 36struct memory_increment {
 37	struct list_head list;
 38	u16 rn;
 39	int standby;
 40};
 41
 42struct sclp_mem {
 43	struct kobject kobj;
 44	unsigned int id;
 45	unsigned int memmap_on_memory;
 46	unsigned int config;
 47#ifdef CONFIG_KASAN
 48	unsigned int early_shadow_mapped;
 49#endif
 50};
 51
 52struct sclp_mem_arg {
 53	struct sclp_mem *sclp_mems;
 54	struct kset *kset;
 55};
 56
 57struct assign_storage_sccb {
 58	struct sccb_header header;
 59	u16 rn;
 60} __packed;
 61
 62struct attach_storage_sccb {
 63	struct sccb_header header;
 64	u16 :16;
 65	u16 assigned;
 66	u32 :32;
 67	u32 entries[];
 68} __packed;
 69
 70int arch_get_memory_phys_device(unsigned long start_pfn)
 71{
 72	if (!sclp.rzm)
 73		return 0;
 74	return PFN_PHYS(start_pfn) >> ilog2(sclp.rzm);
 75}
 76
 77static unsigned long rn2addr(u16 rn)
 78{
 79	return (unsigned long)(rn - 1) * sclp.rzm;
 80}
 81
 82static int do_assign_storage(sclp_cmdw_t cmd, u16 rn)
 83{
 84	struct assign_storage_sccb *sccb;
 85	int rc;
 86
 87	sccb = (void *)get_zeroed_page(GFP_KERNEL | GFP_DMA);
 88	if (!sccb)
 89		return -ENOMEM;
 90	sccb->header.length = PAGE_SIZE;
 91	sccb->rn = rn;
 92	rc = sclp_sync_request_timeout(cmd, sccb, SCLP_QUEUE_INTERVAL);
 93	if (rc)
 94		goto out;
 95	switch (sccb->header.response_code) {
 96	case 0x0020:
 97	case 0x0120:
 98		break;
 99	default:
100		pr_warn("assign storage failed (cmd=0x%08x, response=0x%04x, rn=0x%04x)\n",
101			cmd, sccb->header.response_code, rn);
102		rc = -EIO;
103		break;
104	}
105out:
106	free_page((unsigned long)sccb);
107	return rc;
108}
109
110static int sclp_assign_storage(u16 rn)
111{
112	unsigned long start;
113	int rc;
114
115	rc = do_assign_storage(SCLP_CMDW_ASSIGN_STORAGE, rn);
116	if (rc)
117		return rc;
118	start = rn2addr(rn);
119	storage_key_init_range(start, start + sclp.rzm);
120	return 0;
121}
122
123static int sclp_unassign_storage(u16 rn)
124{
125	return do_assign_storage(SCLP_CMDW_UNASSIGN_STORAGE, rn);
126}
127
128static int sclp_attach_storage(u8 id)
129{
130	struct attach_storage_sccb *sccb;
131	int rc, i;
132
133	sccb = (void *)get_zeroed_page(GFP_KERNEL | GFP_DMA);
134	if (!sccb)
135		return -ENOMEM;
136	sccb->header.length = PAGE_SIZE;
137	sccb->header.function_code = 0x40;
138	rc = sclp_sync_request_timeout(0x00080001 | id << 8, sccb,
139				       SCLP_QUEUE_INTERVAL);
140	if (rc)
141		goto out;
142	switch (sccb->header.response_code) {
143	case 0x0020:
144		set_bit(id, sclp_storage_ids);
145		for (i = 0; i < sccb->assigned; i++) {
146			if (sccb->entries[i])
147				sclp_unassign_storage(sccb->entries[i] >> 16);
148		}
149		break;
150	default:
151		rc = -EIO;
152		break;
153	}
154out:
155	free_page((unsigned long)sccb);
156	return rc;
157}
158
159static int sclp_mem_change_state(unsigned long start, unsigned long size,
160				 int online)
161{
162	struct memory_increment *incr;
163	unsigned long istart;
164	int rc = 0;
165
166	list_for_each_entry(incr, &sclp_mem_list, list) {
167		istart = rn2addr(incr->rn);
168		if (start + size - 1 < istart)
169			break;
170		if (start > istart + sclp.rzm - 1)
171			continue;
172		if (online)
173			rc |= sclp_assign_storage(incr->rn);
174		else
175			sclp_unassign_storage(incr->rn);
176		if (rc == 0)
177			incr->standby = online ? 0 : 1;
178	}
179	return rc ? -EIO : 0;
180}
181
182static ssize_t sclp_config_mem_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
183{
184	struct sclp_mem *sclp_mem = container_of(kobj, struct sclp_mem, kobj);
185
186	return sysfs_emit(buf, "%u\n", READ_ONCE(sclp_mem->config));
187}
188
189static ssize_t sclp_config_mem_store(struct kobject *kobj, struct kobj_attribute *attr,
190				     const char *buf, size_t count)
191{
192	unsigned long addr, block_size;
193	struct sclp_mem *sclp_mem;
194	struct memory_block *mem;
195	unsigned char id;
196	bool value;
197	int rc;
198
199	rc = kstrtobool(buf, &value);
200	if (rc)
201		return rc;
202	sclp_mem = container_of(kobj, struct sclp_mem, kobj);
203	block_size = memory_block_size_bytes();
204	addr = sclp_mem->id * block_size;
205	/*
206	 * Hold device_hotplug_lock when adding/removing memory blocks.
207	 * Additionally, also protect calls to find_memory_block() and
208	 * sclp_attach_storage().
209	 */
210	rc = lock_device_hotplug_sysfs();
211	if (rc)
212		goto out;
213	for_each_clear_bit(id, sclp_storage_ids, sclp_max_storage_id + 1)
214		sclp_attach_storage(id);
215	if (value) {
216		if (sclp_mem->config)
217			goto out_unlock;
218		rc = sclp_mem_change_state(addr, block_size, 1);
219		if (rc)
220			goto out_unlock;
221		/*
222		 * Set entire memory block CMMA state to nodat. Later, when
223		 * page tables pages are allocated via __add_memory(), those
224		 * regions are marked __arch_set_page_dat().
225		 */
226		__arch_set_page_nodat((void *)__va(addr), block_size >> PAGE_SHIFT);
227		rc = __add_memory(0, addr, block_size,
228				  sclp_mem->memmap_on_memory ?
229				  MHP_MEMMAP_ON_MEMORY : MHP_NONE);
230		if (rc) {
231			sclp_mem_change_state(addr, block_size, 0);
232			goto out_unlock;
233		}
234		mem = find_memory_block(pfn_to_section_nr(PFN_DOWN(addr)));
235		put_device(&mem->dev);
236		WRITE_ONCE(sclp_mem->config, 1);
237	} else {
238		if (!sclp_mem->config)
239			goto out_unlock;
240		mem = find_memory_block(pfn_to_section_nr(PFN_DOWN(addr)));
241		if (mem->state != MEM_OFFLINE) {
242			put_device(&mem->dev);
243			rc = -EBUSY;
244			goto out_unlock;
245		}
246		/* drop the ref just got via find_memory_block() */
247		put_device(&mem->dev);
248		sclp_mem_change_state(addr, block_size, 0);
249		__remove_memory(addr, block_size);
250#ifdef CONFIG_KASAN
251		if (sclp_mem->early_shadow_mapped) {
252			unsigned long start, end;
253
254			start = (unsigned long)kasan_mem_to_shadow(__va(addr));
255			end = start + (block_size >> KASAN_SHADOW_SCALE_SHIFT);
256			vmemmap_free(start, end, NULL);
257			sclp_mem->early_shadow_mapped = 0;
258		}
259#endif
260		WRITE_ONCE(sclp_mem->config, 0);
261	}
262out_unlock:
263	unlock_device_hotplug();
264out:
265	return rc ? rc : count;
266}
267
268static struct kobj_attribute sclp_config_mem_attr =
269	__ATTR(config, 0644, sclp_config_mem_show, sclp_config_mem_store);
270
271static ssize_t sclp_memmap_on_memory_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
272{
273	struct sclp_mem *sclp_mem = container_of(kobj, struct sclp_mem, kobj);
274
275	return sysfs_emit(buf, "%u\n", READ_ONCE(sclp_mem->memmap_on_memory));
276}
277
278static ssize_t sclp_memmap_on_memory_store(struct kobject *kobj, struct kobj_attribute *attr,
279					   const char *buf, size_t count)
280{
281	struct sclp_mem *sclp_mem;
282	unsigned long block_size;
283	struct memory_block *mem;
284	bool value;
285	int rc;
286
287	rc = kstrtobool(buf, &value);
288	if (rc)
289		return rc;
290	if (value && !mhp_supports_memmap_on_memory())
291		return -EOPNOTSUPP;
292	rc = lock_device_hotplug_sysfs();
293	if (rc)
294		return rc;
295	block_size = memory_block_size_bytes();
296	sclp_mem = container_of(kobj, struct sclp_mem, kobj);
297	mem = find_memory_block(pfn_to_section_nr(PFN_DOWN(sclp_mem->id * block_size)));
298	if (!mem) {
299		WRITE_ONCE(sclp_mem->memmap_on_memory, value);
300	} else {
301		put_device(&mem->dev);
302		rc = -EBUSY;
303	}
304	unlock_device_hotplug();
305	return rc ? rc : count;
306}
307
308static const struct kobj_type ktype = {
309	.sysfs_ops = &kobj_sysfs_ops,
310};
311
312static struct kobj_attribute sclp_memmap_attr =
313	__ATTR(memmap_on_memory, 0644, sclp_memmap_on_memory_show, sclp_memmap_on_memory_store);
314
315static struct attribute *sclp_mem_attrs[] = {
316	&sclp_config_mem_attr.attr,
317	&sclp_memmap_attr.attr,
318	NULL,
319};
320
321static struct attribute_group sclp_mem_attr_group = {
322	.attrs = sclp_mem_attrs,
323};
324
325static int sclp_create_mem(struct sclp_mem *sclp_mem, struct kset *kset,
326			   unsigned int id, bool config, bool memmap_on_memory)
327{
328	int rc;
329
330	sclp_mem->memmap_on_memory = memmap_on_memory;
331	sclp_mem->config = config;
332#ifdef CONFIG_KASAN
333	sclp_mem->early_shadow_mapped = config;
334#endif
335	sclp_mem->id = id;
336	kobject_init(&sclp_mem->kobj, &ktype);
337	rc = kobject_add(&sclp_mem->kobj, &kset->kobj, "memory%d", id);
338	if (rc)
339		return rc;
340	return sysfs_create_group(&sclp_mem->kobj, &sclp_mem_attr_group);
341}
342
343static int sclp_create_configured_mem(struct memory_block *mem, void *argument)
344{
345	struct sclp_mem *sclp_mems;
346	struct sclp_mem_arg *arg;
347	struct kset *kset;
348	unsigned int id;
349
350	id = mem->dev.id;
351	arg = (struct sclp_mem_arg *)argument;
352	sclp_mems = arg->sclp_mems;
353	kset = arg->kset;
354	return sclp_create_mem(&sclp_mems[id], kset, id, true, false);
355}
356
357static void __init align_to_block_size(unsigned long *start,
358				       unsigned long *size,
359				       unsigned long alignment)
360{
361	unsigned long start_align, size_align;
362
363	start_align = roundup(*start, alignment);
364	size_align = rounddown(*start + *size, alignment) - start_align;
365
366	pr_info("Standby memory at 0x%lx (%luM of %luM usable)\n",
367		*start, size_align >> 20, *size >> 20);
368	*start = start_align;
369	*size = size_align;
370}
371
372static int __init sclp_create_standby_mems_merged(struct sclp_mem *sclp_mems,
373						  struct kset *kset, u16 rn)
374{
375	unsigned long start, size, addr, block_size;
376	static u16 first_rn, num;
377	unsigned int id;
378	int rc = 0;
379
380	if (rn && first_rn && (first_rn + num == rn)) {
381		num++;
382		return rc;
383	}
384	if (!first_rn)
385		goto skip_add;
386	start = rn2addr(first_rn);
387	size = (unsigned long)num * sclp.rzm;
388	if (start >= ident_map_size)
389		goto skip_add;
390	if (start + size > ident_map_size)
391		size = ident_map_size - start;
392	block_size = memory_block_size_bytes();
393	align_to_block_size(&start, &size, block_size);
394	if (!size)
395		goto skip_add;
396	for (addr = start; addr < start + size; addr += block_size) {
397		id = addr / block_size;
398		rc = sclp_create_mem(&sclp_mems[id], kset, id, false,
399				     mhp_supports_memmap_on_memory());
400		if (rc)
401			break;
402	}
403skip_add:
404	first_rn = rn;
405	num = 1;
406	return rc;
407}
408
409static int __init sclp_create_standby_mems(struct sclp_mem *sclp_mems, struct kset *kset)
410{
411	struct memory_increment *incr;
412	int rc = 0;
413
414	list_for_each_entry(incr, &sclp_mem_list, list) {
415		if (incr->standby)
416			rc = sclp_create_standby_mems_merged(sclp_mems, kset, incr->rn);
417		if (rc)
418			return rc;
419	}
420	return sclp_create_standby_mems_merged(sclp_mems, kset, 0);
421}
422
423static int __init sclp_init_mem(void)
424{
425	const unsigned long block_size = memory_block_size_bytes();
426	unsigned int max_sclp_mems;
427	struct sclp_mem *sclp_mems;
428	struct sclp_mem_arg arg;
429	struct kset *kset;
430	int rc;
431
432	max_sclp_mems = roundup(sclp.rnmax * sclp.rzm, block_size) / block_size;
433	/* Allocate memory for all blocks ahead of time. */
434	sclp_mems = kcalloc(max_sclp_mems, sizeof(struct sclp_mem), GFP_KERNEL);
435	if (!sclp_mems)
436		return -ENOMEM;
437	kset = kset_create_and_add("memory", NULL, firmware_kobj);
438	if (!kset)
439		return -ENOMEM;
440	/* Initial memory is in the "configured" state already. */
441	arg.sclp_mems = sclp_mems;
442	arg.kset = kset;
443	rc = for_each_memory_block(&arg, sclp_create_configured_mem);
444	if (rc)
445		return rc;
446	/* Standby memory is "deconfigured". */
447	return sclp_create_standby_mems(sclp_mems, kset);
448}
449
450static void __init insert_increment(u16 rn, int standby, int assigned)
451{
452	struct memory_increment *incr, *new_incr;
453	struct list_head *prev;
454	u16 last_rn;
455
456	new_incr = kzalloc(sizeof(*new_incr), GFP_KERNEL);
457	if (!new_incr)
458		return;
459	new_incr->rn = rn;
460	new_incr->standby = standby;
461	last_rn = 0;
462	prev = &sclp_mem_list;
463	list_for_each_entry(incr, &sclp_mem_list, list) {
464		if (assigned && incr->rn > rn)
465			break;
466		if (!assigned && incr->rn - last_rn > 1)
467			break;
468		last_rn = incr->rn;
469		prev = &incr->list;
470	}
471	if (!assigned)
472		new_incr->rn = last_rn + 1;
473	if (new_incr->rn > sclp.rnmax) {
474		kfree(new_incr);
475		return;
476	}
477	list_add(&new_incr->list, prev);
478}
479
480static int __init sclp_setup_memory(void)
481{
482	struct read_storage_sccb *sccb;
483	int i, id, assigned, rc;
484
485	/* No standby memory in kdump mode */
486	if (oldmem_data.start)
487		return 0;
488	if ((sclp.facilities & 0xe00000000000UL) != 0xe00000000000UL)
489		return 0;
490	rc = -ENOMEM;
491	sccb = (void *)__get_free_page(GFP_KERNEL | GFP_DMA);
492	if (!sccb)
493		goto out;
494	assigned = 0;
495	for (id = 0; id <= sclp_max_storage_id; id++) {
496		memset(sccb, 0, PAGE_SIZE);
497		sccb->header.length = PAGE_SIZE;
498		rc = sclp_sync_request(SCLP_CMDW_READ_STORAGE_INFO | id << 8, sccb);
499		if (rc)
500			goto out;
501		switch (sccb->header.response_code) {
502		case 0x0010:
503			set_bit(id, sclp_storage_ids);
504			for (i = 0; i < sccb->assigned; i++) {
505				if (!sccb->entries[i])
506					continue;
507				assigned++;
508				insert_increment(sccb->entries[i] >> 16, 0, 1);
509			}
510			break;
511		case 0x0310:
512			break;
513		case 0x0410:
514			for (i = 0; i < sccb->assigned; i++) {
515				if (!sccb->entries[i])
516					continue;
517				assigned++;
518				insert_increment(sccb->entries[i] >> 16, 1, 1);
519			}
520			break;
521		default:
522			rc = -EIO;
523			break;
524		}
525		if (!rc)
526			sclp_max_storage_id = sccb->max_id;
527	}
528	if (rc || list_empty(&sclp_mem_list))
529		goto out;
530	for (i = 1; i <= sclp.rnmax - assigned; i++)
531		insert_increment(0, 1, 0);
532	rc = sclp_init_mem();
533out:
534	free_page((unsigned long)sccb);
535	return rc;
536}
537__initcall(sclp_setup_memory);