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
27 static char *cmm_default_sender = "VMRMSVM";
28 #endif
29 static char *sender;
30 module_param(sender, charp, 0400);
31 MODULE_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
38 struct cmm_page_array {
39 struct cmm_page_array *next;
40 unsigned long index;
41 unsigned long pages[CMM_NR_PAGES];
42 };
43
44 static long cmm_pages;
45 static long cmm_timed_pages;
46 static volatile long cmm_pages_target;
47 static volatile long cmm_timed_pages_target;
48 static long cmm_timeout_pages;
49 static long cmm_timeout_seconds;
50
51 static struct cmm_page_array *cmm_page_list;
52 static struct cmm_page_array *cmm_timed_page_list;
53 static DEFINE_SPINLOCK(cmm_lock);
54
55 static struct task_struct *cmm_thread_ptr;
56 static DECLARE_WAIT_QUEUE_HEAD(cmm_thread_wait);
57
58 static void cmm_timer_fn(struct timer_list *);
59 static void cmm_set_timer(void);
60 static DEFINE_TIMER(cmm_timer, cmm_timer_fn);
61
62 static 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(&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(&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(&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(&cmm_lock);
97 nr--;
98 cond_resched();
99 }
100 return nr;
101 }
102
103 static 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(&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(&cmm_lock);
124 return nr;
125 }
126
127 static 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(inc, counter, list);
135 if (inc)
136 break;
137 cond_resched();
138 }
139 return nr + inc;
140 }
141
142 static 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, &cmm_timed_pages, &cmm_timed_page_list);
149 if (nr > 0)
150 nr = cmm_free_pages(nr, &cmm_pages, &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
157 static struct notifier_block cmm_oom_nb = {
158 .notifier_call = cmm_oom_notify,
159 };
160
161 static 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(1, &cmm_pages, &cmm_page_list))
177 cmm_pages_target = cmm_pages;
178 } else if (cmm_pages_target < cmm_pages) {
179 cmm_free_pages(1, &cmm_pages, &cmm_page_list);
180 }
181 if (cmm_timed_pages_target > cmm_timed_pages) {
182 if (cmm_alloc_pages(1, &cmm_timed_pages,
183 &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(1, &cmm_timed_pages,
187 &cmm_timed_page_list);
188 }
189 if (cmm_timed_pages > 0 && !timer_pending(&cmm_timer))
190 cmm_set_timer();
191 }
192 return 0;
193 }
194
195 static void cmm_kick_thread(void)
196 {
197 wake_up(&cmm_thread_wait);
198 }
199
200 static void cmm_set_timer(void)
201 {
202 if (cmm_timed_pages_target <= 0 || cmm_timeout_seconds <= 0) {
203 if (timer_pending(&cmm_timer))
204 del_timer(&cmm_timer);
205 return;
206 }
207 mod_timer(&cmm_timer, jiffies + msecs_to_jiffies(cmm_timeout_seconds * MSEC_PER_SEC));
208 }
209
210 static 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
223 static void cmm_set_pages(long nr)
224 {
225 cmm_pages_target = nr;
226 cmm_kick_thread();
227 }
228
229 static long cmm_get_pages(void)
230 {
231 return cmm_pages;
232 }
233
234 static void cmm_add_timed_pages(long nr)
235 {
236 cmm_timed_pages_target += nr;
237 cmm_kick_thread();
238 }
239
240 static long cmm_get_timed_pages(void)
241 {
242 return cmm_timed_pages;
243 }
244
245 static 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
252 static 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
262 static 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
281 static 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
301 static 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(buf, &p);
318 nr = simple_strtoul(p, &p, 0);
319 cmm_skip_blanks(p, &p);
320 seconds = simple_strtoul(p, &p, 0);
321 cmm_set_timeout(nr, seconds);
322 *ppos += *lenp;
323 } else {
324 len = sprintf(buf, "%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
335 static 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"
355 static 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
391 static struct ctl_table_header *cmm_sysctl_header;
392
393 static 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(&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(cmm_thread_ptr))
416 return 0;
417
418 rc = PTR_ERR(cmm_thread_ptr);
419 unregister_oom_notifier(&cmm_oom_nb);
420 out_oom_notify:
421 #ifdef CONFIG_CMM_IUCV
422 smsg_unregister_callback(SMSG_PREFIX, cmm_smsg_target);
423 out_smsg:
424 #endif
425 unregister_sysctl_table(cmm_sysctl_header);
426 out_sysctl:
427 del_timer_sync(&cmm_timer);
428 return rc;
429 }
430 module_init(cmm_init);
431
432 static void __exit cmm_exit(void)
433 {
434 unregister_sysctl_table(cmm_sysctl_header);
435 #ifdef CONFIG_CMM_IUCV
436 smsg_unregister_callback(SMSG_PREFIX, cmm_smsg_target);
437 #endif
438 unregister_oom_notifier(&cmm_oom_nb);
439 kthread_stop(cmm_thread_ptr);
440 del_timer_sync(&cmm_timer);
441 cmm_free_pages(cmm_pages, &cmm_pages, &cmm_page_list);
442 cmm_free_pages(cmm_timed_pages, &cmm_timed_pages, &cmm_timed_page_list);
443 }
444 module_exit(cmm_exit);
445
446 MODULE_DESCRIPTION("Cooperative memory management interface");
447 MODULE_LICENSE("GPL");
448
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