1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Collaborative memory management interface.
4 *
5 * Copyright IBM Corp 2003, 2010
6 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
7 *
8 */
9
10#include <linux/errno.h>
11#include <linux/fs.h>
12#include <linux/init.h>
13#include <linux/module.h>
14#include <linux/moduleparam.h>
15#include <linux/gfp.h>
16#include <linux/sched.h>
17#include <linux/string_helpers.h>
18#include <linux/sysctl.h>
19#include <linux/swap.h>
20#include <linux/kthread.h>
21#include <linux/oom.h>
22#include <linux/uaccess.h>
23
24#include <asm/diag.h>
25
26#ifdef CONFIG_CMM_IUCV
27static char *cmm_default_sender = "VMRMSVM";
28#endif
29static char *sender;
30module_param(sender, charp, 0400);
31MODULE_PARM_DESC(sender,
32 "Guest name that may send SMSG messages (default VMRMSVM)");
33
34#include "../../../drivers/s390/net/smsgiucv.h"
35
36#define CMM_NR_PAGES ((PAGE_SIZE / sizeof(unsigned long)) - 2)
37
38struct cmm_page_array {
39 struct cmm_page_array *next;
40 unsigned long index;
41 unsigned long pages[CMM_NR_PAGES];
42};
43
44static long cmm_pages;
45static long cmm_timed_pages;
46static volatile long cmm_pages_target;
47static volatile long cmm_timed_pages_target;
48static long cmm_timeout_pages;
49static long cmm_timeout_seconds;
50
51static struct cmm_page_array *cmm_page_list;
52static struct cmm_page_array *cmm_timed_page_list;
53static DEFINE_SPINLOCK(cmm_lock);
54
55static struct task_struct *cmm_thread_ptr;
56static DECLARE_WAIT_QUEUE_HEAD(cmm_thread_wait);
57
58static void cmm_timer_fn(struct timer_list *);
59static void cmm_set_timer(void);
60static DEFINE_TIMER(cmm_timer, cmm_timer_fn);
61
62static long cmm_alloc_pages(long nr, long *counter,
63 struct cmm_page_array **list)
64{
65 struct cmm_page_array *pa, *npa;
66 unsigned long addr;
67
68 while (nr) {
69 addr = __get_free_page(GFP_NOIO);
70 if (!addr)
71 break;
72 spin_lock(lock: &cmm_lock);
73 pa = *list;
74 if (!pa || pa->index >= CMM_NR_PAGES) {
75 /* Need a new page for the page list. */
76 spin_unlock(lock: &cmm_lock);
77 npa = (struct cmm_page_array *)
78 __get_free_page(GFP_NOIO);
79 if (!npa) {
80 free_page(addr);
81 break;
82 }
83 spin_lock(lock: &cmm_lock);
84 pa = *list;
85 if (!pa || pa->index >= CMM_NR_PAGES) {
86 npa->next = pa;
87 npa->index = 0;
88 pa = npa;
89 *list = pa;
90 } else
91 free_page((unsigned long) npa);
92 }
93 diag10_range(virt_to_pfn((void *)addr), 1);
94 pa->pages[pa->index++] = addr;
95 (*counter)++;
96 spin_unlock(lock: &cmm_lock);
97 nr--;
98 cond_resched();
99 }
100 return nr;
101}
102
103static long __cmm_free_pages(long nr, long *counter, struct cmm_page_array **list)
104{
105 struct cmm_page_array *pa;
106 unsigned long addr;
107
108 spin_lock(lock: &cmm_lock);
109 pa = *list;
110 while (nr) {
111 if (!pa || pa->index <= 0)
112 break;
113 addr = pa->pages[--pa->index];
114 if (pa->index == 0) {
115 pa = pa->next;
116 free_page((unsigned long) *list);
117 *list = pa;
118 }
119 free_page(addr);
120 (*counter)--;
121 nr--;
122 }
123 spin_unlock(lock: &cmm_lock);
124 return nr;
125}
126
127static long cmm_free_pages(long nr, long *counter, struct cmm_page_array **list)
128{
129 long inc = 0;
130
131 while (nr) {
132 inc = min(256L, nr);
133 nr -= inc;
134 inc = __cmm_free_pages(nr: inc, counter, list);
135 if (inc)
136 break;
137 cond_resched();
138 }
139 return nr + inc;
140}
141
142static int cmm_oom_notify(struct notifier_block *self,
143 unsigned long dummy, void *parm)
144{
145 unsigned long *freed = parm;
146 long nr = 256;
147
148 nr = cmm_free_pages(nr, counter: &cmm_timed_pages, list: &cmm_timed_page_list);
149 if (nr > 0)
150 nr = cmm_free_pages(nr, counter: &cmm_pages, list: &cmm_page_list);
151 cmm_pages_target = cmm_pages;
152 cmm_timed_pages_target = cmm_timed_pages;
153 *freed += 256 - nr;
154 return NOTIFY_OK;
155}
156
157static struct notifier_block cmm_oom_nb = {
158 .notifier_call = cmm_oom_notify,
159};
160
161static int cmm_thread(void *dummy)
162{
163 int rc;
164
165 while (1) {
166 rc = wait_event_interruptible(cmm_thread_wait,
167 cmm_pages != cmm_pages_target ||
168 cmm_timed_pages != cmm_timed_pages_target ||
169 kthread_should_stop());
170 if (kthread_should_stop() || rc == -ERESTARTSYS) {
171 cmm_pages_target = cmm_pages;
172 cmm_timed_pages_target = cmm_timed_pages;
173 break;
174 }
175 if (cmm_pages_target > cmm_pages) {
176 if (cmm_alloc_pages(nr: 1, counter: &cmm_pages, list: &cmm_page_list))
177 cmm_pages_target = cmm_pages;
178 } else if (cmm_pages_target < cmm_pages) {
179 cmm_free_pages(nr: 1, counter: &cmm_pages, list: &cmm_page_list);
180 }
181 if (cmm_timed_pages_target > cmm_timed_pages) {
182 if (cmm_alloc_pages(nr: 1, counter: &cmm_timed_pages,
183 list: &cmm_timed_page_list))
184 cmm_timed_pages_target = cmm_timed_pages;
185 } else if (cmm_timed_pages_target < cmm_timed_pages) {
186 cmm_free_pages(nr: 1, counter: &cmm_timed_pages,
187 list: &cmm_timed_page_list);
188 }
189 if (cmm_timed_pages > 0 && !timer_pending(timer: &cmm_timer))
190 cmm_set_timer();
191 }
192 return 0;
193}
194
195static void cmm_kick_thread(void)
196{
197 wake_up(&cmm_thread_wait);
198}
199
200static void cmm_set_timer(void)
201{
202 if (cmm_timed_pages_target <= 0 || cmm_timeout_seconds <= 0) {
203 if (timer_pending(timer: &cmm_timer))
204 timer_delete(timer: &cmm_timer);
205 return;
206 }
207 mod_timer(timer: &cmm_timer, expires: jiffies + secs_to_jiffies(cmm_timeout_seconds));
208}
209
210static void cmm_timer_fn(struct timer_list *unused)
211{
212 long nr;
213
214 nr = cmm_timed_pages_target - cmm_timeout_pages;
215 if (nr < 0)
216 cmm_timed_pages_target = 0;
217 else
218 cmm_timed_pages_target = nr;
219 cmm_kick_thread();
220 cmm_set_timer();
221}
222
223static void cmm_set_pages(long nr)
224{
225 cmm_pages_target = nr;
226 cmm_kick_thread();
227}
228
229static long cmm_get_pages(void)
230{
231 return cmm_pages;
232}
233
234static void cmm_add_timed_pages(long nr)
235{
236 cmm_timed_pages_target += nr;
237 cmm_kick_thread();
238}
239
240static long cmm_get_timed_pages(void)
241{
242 return cmm_timed_pages;
243}
244
245static void cmm_set_timeout(long nr, long seconds)
246{
247 cmm_timeout_pages = nr;
248 cmm_timeout_seconds = seconds;
249 cmm_set_timer();
250}
251
252static int cmm_skip_blanks(char *cp, char **endp)
253{
254 char *str;
255
256 for (str = cp; *str == ' ' || *str == '\t'; str++)
257 ;
258 *endp = str;
259 return str != cp;
260}
261
262static int cmm_pages_handler(const struct ctl_table *ctl, int write,
263 void *buffer, size_t *lenp, loff_t *ppos)
264{
265 long nr = cmm_get_pages();
266 struct ctl_table ctl_entry = {
267 .procname = ctl->procname,
268 .data = &nr,
269 .maxlen = sizeof(long),
270 };
271 int rc;
272
273 rc = proc_doulongvec_minmax(&ctl_entry, write, buffer, lenp, ppos);
274 if (rc < 0 || !write)
275 return rc;
276
277 cmm_set_pages(nr);
278 return 0;
279}
280
281static int cmm_timed_pages_handler(const struct ctl_table *ctl, int write,
282 void *buffer, size_t *lenp,
283 loff_t *ppos)
284{
285 long nr = cmm_get_timed_pages();
286 struct ctl_table ctl_entry = {
287 .procname = ctl->procname,
288 .data = &nr,
289 .maxlen = sizeof(long),
290 };
291 int rc;
292
293 rc = proc_doulongvec_minmax(&ctl_entry, write, buffer, lenp, ppos);
294 if (rc < 0 || !write)
295 return rc;
296
297 cmm_add_timed_pages(nr);
298 return 0;
299}
300
301static int cmm_timeout_handler(const struct ctl_table *ctl, int write,
302 void *buffer, size_t *lenp, loff_t *ppos)
303{
304 char buf[64], *p;
305 long nr, seconds;
306 unsigned int len;
307
308 if (!*lenp || (*ppos && !write)) {
309 *lenp = 0;
310 return 0;
311 }
312
313 if (write) {
314 len = min(*lenp, sizeof(buf));
315 memcpy(buf, buffer, len);
316 buf[len - 1] = '\0';
317 cmm_skip_blanks(cp: buf, endp: &p);
318 nr = simple_strtoul(p, &p, 0);
319 cmm_skip_blanks(cp: p, endp: &p);
320 seconds = simple_strtoul(p, &p, 0);
321 cmm_set_timeout(nr, seconds);
322 *ppos += *lenp;
323 } else {
324 len = scnprintf(buf, size: sizeof(buf), fmt: "%ld %ld\n",
325 cmm_timeout_pages, cmm_timeout_seconds);
326 if (len > *lenp)
327 len = *lenp;
328 memcpy(buffer, buf, len);
329 *lenp = len;
330 *ppos += len;
331 }
332 return 0;
333}
334
335static const struct ctl_table cmm_table[] = {
336 {
337 .procname = "cmm_pages",
338 .mode = 0644,
339 .proc_handler = cmm_pages_handler,
340 },
341 {
342 .procname = "cmm_timed_pages",
343 .mode = 0644,
344 .proc_handler = cmm_timed_pages_handler,
345 },
346 {
347 .procname = "cmm_timeout",
348 .mode = 0644,
349 .proc_handler = cmm_timeout_handler,
350 },
351};
352
353#ifdef CONFIG_CMM_IUCV
354#define SMSG_PREFIX "CMM"
355static void cmm_smsg_target(const char *from, char *msg)
356{
357 long nr, seconds;
358
359 if (strlen(sender) > 0 && strcmp(from, sender) != 0)
360 return;
361 if (!cmm_skip_blanks(msg + strlen(SMSG_PREFIX), &msg))
362 return;
363 if (strncmp(msg, "SHRINK", 6) == 0) {
364 if (!cmm_skip_blanks(msg + 6, &msg))
365 return;
366 nr = simple_strtoul(msg, &msg, 0);
367 cmm_skip_blanks(msg, &msg);
368 if (*msg == '\0')
369 cmm_set_pages(nr);
370 } else if (strncmp(msg, "RELEASE", 7) == 0) {
371 if (!cmm_skip_blanks(msg + 7, &msg))
372 return;
373 nr = simple_strtoul(msg, &msg, 0);
374 cmm_skip_blanks(msg, &msg);
375 if (*msg == '\0')
376 cmm_add_timed_pages(nr);
377 } else if (strncmp(msg, "REUSE", 5) == 0) {
378 if (!cmm_skip_blanks(msg + 5, &msg))
379 return;
380 nr = simple_strtoul(msg, &msg, 0);
381 if (!cmm_skip_blanks(msg, &msg))
382 return;
383 seconds = simple_strtoul(msg, &msg, 0);
384 cmm_skip_blanks(msg, &msg);
385 if (*msg == '\0')
386 cmm_set_timeout(nr, seconds);
387 }
388}
389#endif
390
391static struct ctl_table_header *cmm_sysctl_header;
392
393static int __init cmm_init(void)
394{
395 int rc = -ENOMEM;
396
397 cmm_sysctl_header = register_sysctl("vm", cmm_table);
398 if (!cmm_sysctl_header)
399 goto out_sysctl;
400#ifdef CONFIG_CMM_IUCV
401 /* convert sender to uppercase characters */
402 if (sender)
403 string_upper(sender, sender);
404 else
405 sender = cmm_default_sender;
406
407 rc = smsg_register_callback(SMSG_PREFIX, cmm_smsg_target);
408 if (rc < 0)
409 goto out_smsg;
410#endif
411 rc = register_oom_notifier(nb: &cmm_oom_nb);
412 if (rc < 0)
413 goto out_oom_notify;
414 cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
415 if (!IS_ERR(ptr: cmm_thread_ptr))
416 return 0;
417
418 rc = PTR_ERR(ptr: cmm_thread_ptr);
419 unregister_oom_notifier(nb: &cmm_oom_nb);
420out_oom_notify:
421#ifdef CONFIG_CMM_IUCV
422 smsg_unregister_callback(SMSG_PREFIX, cmm_smsg_target);
423out_smsg:
424#endif
425 unregister_sysctl_table(table: cmm_sysctl_header);
426out_sysctl:
427 timer_delete_sync(timer: &cmm_timer);
428 return rc;
429}
430module_init(cmm_init);
431
432static void __exit cmm_exit(void)
433{
434 unregister_sysctl_table(table: cmm_sysctl_header);
435#ifdef CONFIG_CMM_IUCV
436 smsg_unregister_callback(SMSG_PREFIX, cmm_smsg_target);
437#endif
438 unregister_oom_notifier(nb: &cmm_oom_nb);
439 kthread_stop(k: cmm_thread_ptr);
440 timer_delete_sync(timer: &cmm_timer);
441 cmm_free_pages(nr: cmm_pages, counter: &cmm_pages, list: &cmm_page_list);
442 cmm_free_pages(nr: cmm_timed_pages, counter: &cmm_timed_pages, list: &cmm_timed_page_list);
443}
444module_exit(cmm_exit);
445
446MODULE_DESCRIPTION("Cooperative memory management interface");
447MODULE_LICENSE("GPL");
448

source code of linux/arch/s390/mm/cmm.c