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