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 } 99 return nr; 100 } 101 102 static long __cmm_free_pages(long nr, long *counter, struct cmm_page_array **list) 103 { 104 struct cmm_page_array *pa; 105 unsigned long addr; 106 107 spin_lock(&cmm_lock); 108 pa = *list; 109 while (nr) { 110 if (!pa || pa->index <= 0) 111 break; 112 addr = pa->pages[--pa->index]; 113 if (pa->index == 0) { 114 pa = pa->next; 115 free_page((unsigned long) *list); 116 *list = pa; 117 } 118 free_page(addr); 119 (*counter)--; 120 nr--; 121 } 122 spin_unlock(&cmm_lock); 123 return nr; 124 } 125 126 static long cmm_free_pages(long nr, long *counter, struct cmm_page_array **list) 127 { 128 long inc = 0; 129 130 while (nr) { 131 inc = min(256L, nr); 132 nr -= inc; 133 inc = __cmm_free_pages(inc, counter, list); 134 if (inc) 135 break; 136 } 137 return nr + inc; 138 } 139 140 static int cmm_oom_notify(struct notifier_block *self, 141 unsigned long dummy, void *parm) 142 { 143 unsigned long *freed = parm; 144 long nr = 256; 145 146 nr = cmm_free_pages(nr, &cmm_timed_pages, &cmm_timed_page_list); 147 if (nr > 0) 148 nr = cmm_free_pages(nr, &cmm_pages, &cmm_page_list); 149 cmm_pages_target = cmm_pages; 150 cmm_timed_pages_target = cmm_timed_pages; 151 *freed += 256 - nr; 152 return NOTIFY_OK; 153 } 154 155 static struct notifier_block cmm_oom_nb = { 156 .notifier_call = cmm_oom_notify, 157 }; 158 159 static int cmm_thread(void *dummy) 160 { 161 int rc; 162 163 while (1) { 164 rc = wait_event_interruptible(cmm_thread_wait, 165 cmm_pages != cmm_pages_target || 166 cmm_timed_pages != cmm_timed_pages_target || 167 kthread_should_stop()); 168 if (kthread_should_stop() || rc == -ERESTARTSYS) { 169 cmm_pages_target = cmm_pages; 170 cmm_timed_pages_target = cmm_timed_pages; 171 break; 172 } 173 if (cmm_pages_target > cmm_pages) { 174 if (cmm_alloc_pages(1, &cmm_pages, &cmm_page_list)) 175 cmm_pages_target = cmm_pages; 176 } else if (cmm_pages_target < cmm_pages) { 177 cmm_free_pages(1, &cmm_pages, &cmm_page_list); 178 } 179 if (cmm_timed_pages_target > cmm_timed_pages) { 180 if (cmm_alloc_pages(1, &cmm_timed_pages, 181 &cmm_timed_page_list)) 182 cmm_timed_pages_target = cmm_timed_pages; 183 } else if (cmm_timed_pages_target < cmm_timed_pages) { 184 cmm_free_pages(1, &cmm_timed_pages, 185 &cmm_timed_page_list); 186 } 187 if (cmm_timed_pages > 0 && !timer_pending(&cmm_timer)) 188 cmm_set_timer(); 189 } 190 return 0; 191 } 192 193 static void cmm_kick_thread(void) 194 { 195 wake_up(&cmm_thread_wait); 196 } 197 198 static void cmm_set_timer(void) 199 { 200 if (cmm_timed_pages_target <= 0 || cmm_timeout_seconds <= 0) { 201 if (timer_pending(&cmm_timer)) 202 timer_delete(&cmm_timer); 203 return; 204 } 205 mod_timer(&cmm_timer, jiffies + secs_to_jiffies(cmm_timeout_seconds)); 206 } 207 208 static void cmm_timer_fn(struct timer_list *unused) 209 { 210 long nr; 211 212 nr = cmm_timed_pages_target - cmm_timeout_pages; 213 if (nr < 0) 214 cmm_timed_pages_target = 0; 215 else 216 cmm_timed_pages_target = nr; 217 cmm_kick_thread(); 218 cmm_set_timer(); 219 } 220 221 static void cmm_set_pages(long nr) 222 { 223 cmm_pages_target = nr; 224 cmm_kick_thread(); 225 } 226 227 static long cmm_get_pages(void) 228 { 229 return cmm_pages; 230 } 231 232 static void cmm_add_timed_pages(long nr) 233 { 234 cmm_timed_pages_target += nr; 235 cmm_kick_thread(); 236 } 237 238 static long cmm_get_timed_pages(void) 239 { 240 return cmm_timed_pages; 241 } 242 243 static void cmm_set_timeout(long nr, long seconds) 244 { 245 cmm_timeout_pages = nr; 246 cmm_timeout_seconds = seconds; 247 cmm_set_timer(); 248 } 249 250 static int cmm_skip_blanks(char *cp, char **endp) 251 { 252 char *str; 253 254 for (str = cp; *str == ' ' || *str == '\t'; str++) 255 ; 256 *endp = str; 257 return str != cp; 258 } 259 260 static int cmm_pages_handler(const struct ctl_table *ctl, int write, 261 void *buffer, size_t *lenp, loff_t *ppos) 262 { 263 long nr = cmm_get_pages(); 264 struct ctl_table ctl_entry = { 265 .procname = ctl->procname, 266 .data = &nr, 267 .maxlen = sizeof(long), 268 }; 269 int rc; 270 271 rc = proc_doulongvec_minmax(&ctl_entry, write, buffer, lenp, ppos); 272 if (rc < 0 || !write) 273 return rc; 274 275 cmm_set_pages(nr); 276 return 0; 277 } 278 279 static int cmm_timed_pages_handler(const struct ctl_table *ctl, int write, 280 void *buffer, size_t *lenp, 281 loff_t *ppos) 282 { 283 long nr = cmm_get_timed_pages(); 284 struct ctl_table ctl_entry = { 285 .procname = ctl->procname, 286 .data = &nr, 287 .maxlen = sizeof(long), 288 }; 289 int rc; 290 291 rc = proc_doulongvec_minmax(&ctl_entry, write, buffer, lenp, ppos); 292 if (rc < 0 || !write) 293 return rc; 294 295 cmm_add_timed_pages(nr); 296 return 0; 297 } 298 299 static int cmm_timeout_handler(const struct ctl_table *ctl, int write, 300 void *buffer, size_t *lenp, loff_t *ppos) 301 { 302 char buf[64], *p; 303 long nr, seconds; 304 unsigned int len; 305 306 if (!*lenp || (*ppos && !write)) { 307 *lenp = 0; 308 return 0; 309 } 310 311 if (write) { 312 len = min(*lenp, sizeof(buf)); 313 memcpy(buf, buffer, len); 314 buf[len - 1] = '\0'; 315 cmm_skip_blanks(buf, &p); 316 nr = simple_strtoul(p, &p, 0); 317 cmm_skip_blanks(p, &p); 318 seconds = simple_strtoul(p, &p, 0); 319 cmm_set_timeout(nr, seconds); 320 *ppos += *lenp; 321 } else { 322 len = scnprintf(buf, sizeof(buf), "%ld %ld\n", 323 cmm_timeout_pages, cmm_timeout_seconds); 324 if (len > *lenp) 325 len = *lenp; 326 memcpy(buffer, buf, len); 327 *lenp = len; 328 *ppos += len; 329 } 330 return 0; 331 } 332 333 static const struct ctl_table cmm_table[] = { 334 { 335 .procname = "cmm_pages", 336 .mode = 0644, 337 .proc_handler = cmm_pages_handler, 338 }, 339 { 340 .procname = "cmm_timed_pages", 341 .mode = 0644, 342 .proc_handler = cmm_timed_pages_handler, 343 }, 344 { 345 .procname = "cmm_timeout", 346 .mode = 0644, 347 .proc_handler = cmm_timeout_handler, 348 }, 349 }; 350 351 #ifdef CONFIG_CMM_IUCV 352 #define SMSG_PREFIX "CMM" 353 static void cmm_smsg_target(const char *from, char *msg) 354 { 355 long nr, seconds; 356 357 if (strlen(sender) > 0 && strcmp(from, sender) != 0) 358 return; 359 if (!cmm_skip_blanks(msg + strlen(SMSG_PREFIX), &msg)) 360 return; 361 if (strncmp(msg, "SHRINK", 6) == 0) { 362 if (!cmm_skip_blanks(msg + 6, &msg)) 363 return; 364 nr = simple_strtoul(msg, &msg, 0); 365 cmm_skip_blanks(msg, &msg); 366 if (*msg == '\0') 367 cmm_set_pages(nr); 368 } else if (strncmp(msg, "RELEASE", 7) == 0) { 369 if (!cmm_skip_blanks(msg + 7, &msg)) 370 return; 371 nr = simple_strtoul(msg, &msg, 0); 372 cmm_skip_blanks(msg, &msg); 373 if (*msg == '\0') 374 cmm_add_timed_pages(nr); 375 } else if (strncmp(msg, "REUSE", 5) == 0) { 376 if (!cmm_skip_blanks(msg + 5, &msg)) 377 return; 378 nr = simple_strtoul(msg, &msg, 0); 379 if (!cmm_skip_blanks(msg, &msg)) 380 return; 381 seconds = simple_strtoul(msg, &msg, 0); 382 cmm_skip_blanks(msg, &msg); 383 if (*msg == '\0') 384 cmm_set_timeout(nr, seconds); 385 } 386 } 387 #endif 388 389 static struct ctl_table_header *cmm_sysctl_header; 390 391 static int __init cmm_init(void) 392 { 393 int rc = -ENOMEM; 394 395 cmm_sysctl_header = register_sysctl("vm", cmm_table); 396 if (!cmm_sysctl_header) 397 goto out_sysctl; 398 #ifdef CONFIG_CMM_IUCV 399 /* convert sender to uppercase characters */ 400 if (sender) 401 string_upper(sender, sender); 402 else 403 sender = cmm_default_sender; 404 405 rc = smsg_register_callback(SMSG_PREFIX, cmm_smsg_target); 406 if (rc < 0) 407 goto out_smsg; 408 #endif 409 rc = register_oom_notifier(&cmm_oom_nb); 410 if (rc < 0) 411 goto out_oom_notify; 412 cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread"); 413 if (!IS_ERR(cmm_thread_ptr)) 414 return 0; 415 416 rc = PTR_ERR(cmm_thread_ptr); 417 unregister_oom_notifier(&cmm_oom_nb); 418 out_oom_notify: 419 #ifdef CONFIG_CMM_IUCV 420 smsg_unregister_callback(SMSG_PREFIX, cmm_smsg_target); 421 out_smsg: 422 #endif 423 unregister_sysctl_table(cmm_sysctl_header); 424 out_sysctl: 425 timer_delete_sync(&cmm_timer); 426 return rc; 427 } 428 module_init(cmm_init); 429 430 static void __exit cmm_exit(void) 431 { 432 unregister_sysctl_table(cmm_sysctl_header); 433 #ifdef CONFIG_CMM_IUCV 434 smsg_unregister_callback(SMSG_PREFIX, cmm_smsg_target); 435 #endif 436 unregister_oom_notifier(&cmm_oom_nb); 437 kthread_stop(cmm_thread_ptr); 438 timer_delete_sync(&cmm_timer); 439 cmm_free_pages(cmm_pages, &cmm_pages, &cmm_page_list); 440 cmm_free_pages(cmm_timed_pages, &cmm_timed_pages, &cmm_timed_page_list); 441 } 442 module_exit(cmm_exit); 443 444 MODULE_DESCRIPTION("Cooperative memory management interface"); 445 MODULE_LICENSE("GPL"); 446