arch/s390/mm/cmm.c

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