s390/mm/cmm.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  *  Collaborative memory management interface.
0004  *
0005  *    Copyright IBM Corp 2003, 2010
0006  *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
0007  *
0008  */
0009
0010 #include <linux/errno.h>
0011 #include <linux/fs.h>
0012 #include <linux/init.h>
0013 #include <linux/module.h>
0014 #include <linux/moduleparam.h>
0015 #include <linux/gfp.h>
0016 #include <linux/sched.h>
0017 #include <linux/string_helpers.h>
0018 #include <linux/sysctl.h>
0019 #include <linux/swap.h>
0020 #include <linux/kthread.h>
0021 #include <linux/oom.h>
0022 #include <linux/uaccess.h>
0023
0024 #include <asm/diag.h>
0025
0026 #ifdef CONFIG_CMM_IUCV
0027 static char *cmm_default_sender = "VMRMSVM";
0028 #endif
0029 static char *sender;
0030 module_param(sender, charp, 0400);
0031 MODULE_PARM_DESC(sender,
0032          "Guest name that may send SMSG messages (default VMRMSVM)");
0033
0034 #include "../../../drivers/s390/net/smsgiucv.h"
0035
0036 #define CMM_NR_PAGES ((PAGE_SIZE / sizeof(unsigned long)) - 2)
0037
0038 struct cmm_page_array {
0039     struct cmm_page_array *next;
0040     unsigned long index;
0041     unsigned long pages[CMM_NR_PAGES];
0042 };
0043
0044 static long cmm_pages;
0045 static long cmm_timed_pages;
0046 static volatile long cmm_pages_target;
0047 static volatile long cmm_timed_pages_target;
0048 static long cmm_timeout_pages;
0049 static long cmm_timeout_seconds;
0050
0051 static struct cmm_page_array *cmm_page_list;
0052 static struct cmm_page_array *cmm_timed_page_list;
0053 static DEFINE_SPINLOCK(cmm_lock);
0054
0055 static struct task_struct *cmm_thread_ptr;
0056 static DECLARE_WAIT_QUEUE_HEAD(cmm_thread_wait);
0057
0058 static void cmm_timer_fn(struct timer_list *);
0059 static void cmm_set_timer(void);
0060 static DEFINE_TIMER(cmm_timer, cmm_timer_fn);
0061
0062 static long cmm_alloc_pages(long nr, long *counter,
0063                 struct cmm_page_array **list)
0064 {
0065     struct cmm_page_array *pa, *npa;
0066     unsigned long addr;
0067
0068     while (nr) {
0069         addr = __get_free_page(GFP_NOIO);
0070         if (!addr)
0071             break;
0072         spin_lock(&cmm_lock);
0073         pa = *list;
0074         if (!pa || pa->index >= CMM_NR_PAGES) {
0075             /* Need a new page for the page list. */
0076             spin_unlock(&cmm_lock);
0077             npa = (struct cmm_page_array *)
0078                 __get_free_page(GFP_NOIO);
0079             if (!npa) {
0080                 free_page(addr);
0081                 break;
0082             }
0083             spin_lock(&cmm_lock);
0084             pa = *list;
0085             if (!pa || pa->index >= CMM_NR_PAGES) {
0086                 npa->next = pa;
0087                 npa->index = 0;
0088                 pa = npa;
0089                 *list = pa;
0090             } else
0091                 free_page((unsigned long) npa);
0092         }
0093         diag10_range(virt_to_pfn(addr), 1);
0094         pa->pages[pa->index++] = addr;
0095         (*counter)++;
0096         spin_unlock(&cmm_lock);
0097         nr--;
0098     }
0099     return nr;
0100 }
0101
0102 static long cmm_free_pages(long nr, long *counter, struct cmm_page_array **list)
0103 {
0104     struct cmm_page_array *pa;
0105     unsigned long addr;
0106
0107     spin_lock(&cmm_lock);
0108     pa = *list;
0109     while (nr) {
0110         if (!pa || pa->index <= 0)
0111             break;
0112         addr = pa->pages[--pa->index];
0113         if (pa->index == 0) {
0114             pa = pa->next;
0115             free_page((unsigned long) *list);
0116             *list = pa;
0117         }
0118         free_page(addr);
0119         (*counter)--;
0120         nr--;
0121     }
0122     spin_unlock(&cmm_lock);
0123     return nr;
0124 }
0125
0126 static int cmm_oom_notify(struct notifier_block *self,
0127               unsigned long dummy, void *parm)
0128 {
0129     unsigned long *freed = parm;
0130     long nr = 256;
0131
0132     nr = cmm_free_pages(nr, &cmm_timed_pages, &cmm_timed_page_list);
0133     if (nr > 0)
0134         nr = cmm_free_pages(nr, &cmm_pages, &cmm_page_list);
0135     cmm_pages_target = cmm_pages;
0136     cmm_timed_pages_target = cmm_timed_pages;
0137     *freed += 256 - nr;
0138     return NOTIFY_OK;
0139 }
0140
0141 static struct notifier_block cmm_oom_nb = {
0142     .notifier_call = cmm_oom_notify,
0143 };
0144
0145 static int cmm_thread(void *dummy)
0146 {
0147     int rc;
0148
0149     while (1) {
0150         rc = wait_event_interruptible(cmm_thread_wait,
0151             cmm_pages != cmm_pages_target ||
0152             cmm_timed_pages != cmm_timed_pages_target ||
0153             kthread_should_stop());
0154         if (kthread_should_stop() || rc == -ERESTARTSYS) {
0155             cmm_pages_target = cmm_pages;
0156             cmm_timed_pages_target = cmm_timed_pages;
0157             break;
0158         }
0159         if (cmm_pages_target > cmm_pages) {
0160             if (cmm_alloc_pages(1, &cmm_pages, &cmm_page_list))
0161                 cmm_pages_target = cmm_pages;
0162         } else if (cmm_pages_target < cmm_pages) {
0163             cmm_free_pages(1, &cmm_pages, &cmm_page_list);
0164         }
0165         if (cmm_timed_pages_target > cmm_timed_pages) {
0166             if (cmm_alloc_pages(1, &cmm_timed_pages,
0167                        &cmm_timed_page_list))
0168                 cmm_timed_pages_target = cmm_timed_pages;
0169         } else if (cmm_timed_pages_target < cmm_timed_pages) {
0170             cmm_free_pages(1, &cmm_timed_pages,
0171                        &cmm_timed_page_list);
0172         }
0173         if (cmm_timed_pages > 0 && !timer_pending(&cmm_timer))
0174             cmm_set_timer();
0175     }
0176     return 0;
0177 }
0178
0179 static void cmm_kick_thread(void)
0180 {
0181     wake_up(&cmm_thread_wait);
0182 }
0183
0184 static void cmm_set_timer(void)
0185 {
0186     if (cmm_timed_pages_target <= 0 || cmm_timeout_seconds <= 0) {
0187         if (timer_pending(&cmm_timer))
0188             del_timer(&cmm_timer);
0189         return;
0190     }
0191     mod_timer(&cmm_timer, jiffies + msecs_to_jiffies(cmm_timeout_seconds * MSEC_PER_SEC));
0192 }
0193
0194 static void cmm_timer_fn(struct timer_list *unused)
0195 {
0196     long nr;
0197
0198     nr = cmm_timed_pages_target - cmm_timeout_pages;
0199     if (nr < 0)
0200         cmm_timed_pages_target = 0;
0201     else
0202         cmm_timed_pages_target = nr;
0203     cmm_kick_thread();
0204     cmm_set_timer();
0205 }
0206
0207 static void cmm_set_pages(long nr)
0208 {
0209     cmm_pages_target = nr;
0210     cmm_kick_thread();
0211 }
0212
0213 static long cmm_get_pages(void)
0214 {
0215     return cmm_pages;
0216 }
0217
0218 static void cmm_add_timed_pages(long nr)
0219 {
0220     cmm_timed_pages_target += nr;
0221     cmm_kick_thread();
0222 }
0223
0224 static long cmm_get_timed_pages(void)
0225 {
0226     return cmm_timed_pages;
0227 }
0228
0229 static void cmm_set_timeout(long nr, long seconds)
0230 {
0231     cmm_timeout_pages = nr;
0232     cmm_timeout_seconds = seconds;
0233     cmm_set_timer();
0234 }
0235
0236 static int cmm_skip_blanks(char *cp, char **endp)
0237 {
0238     char *str;
0239
0240     for (str = cp; *str == ' ' || *str == '\t'; str++)
0241         ;
0242     *endp = str;
0243     return str != cp;
0244 }
0245
0246 static int cmm_pages_handler(struct ctl_table *ctl, int write,
0247                  void *buffer, size_t *lenp, loff_t *ppos)
0248 {
0249     long nr = cmm_get_pages();
0250     struct ctl_table ctl_entry = {
0251         .procname   = ctl->procname,
0252         .data       = &nr,
0253         .maxlen     = sizeof(long),
0254     };
0255     int rc;
0256
0257     rc = proc_doulongvec_minmax(&ctl_entry, write, buffer, lenp, ppos);
0258     if (rc < 0 || !write)
0259         return rc;
0260
0261     cmm_set_pages(nr);
0262     return 0;
0263 }
0264
0265 static int cmm_timed_pages_handler(struct ctl_table *ctl, int write,
0266                    void *buffer, size_t *lenp,
0267                    loff_t *ppos)
0268 {
0269     long nr = cmm_get_timed_pages();
0270     struct ctl_table ctl_entry = {
0271         .procname   = ctl->procname,
0272         .data       = &nr,
0273         .maxlen     = sizeof(long),
0274     };
0275     int rc;
0276
0277     rc = proc_doulongvec_minmax(&ctl_entry, write, buffer, lenp, ppos);
0278     if (rc < 0 || !write)
0279         return rc;
0280
0281     cmm_add_timed_pages(nr);
0282     return 0;
0283 }
0284
0285 static int cmm_timeout_handler(struct ctl_table *ctl, int write,
0286                    void *buffer, size_t *lenp, loff_t *ppos)
0287 {
0288     char buf[64], *p;
0289     long nr, seconds;
0290     unsigned int len;
0291
0292     if (!*lenp || (*ppos && !write)) {
0293         *lenp = 0;
0294         return 0;
0295     }
0296
0297     if (write) {
0298         len = min(*lenp, sizeof(buf));
0299         memcpy(buf, buffer, len);
0300         buf[len - 1] = '\0';
0301         cmm_skip_blanks(buf, &p);
0302         nr = simple_strtoul(p, &p, 0);
0303         cmm_skip_blanks(p, &p);
0304         seconds = simple_strtoul(p, &p, 0);
0305         cmm_set_timeout(nr, seconds);
0306         *ppos += *lenp;
0307     } else {
0308         len = sprintf(buf, "%ld %ld\n",
0309                   cmm_timeout_pages, cmm_timeout_seconds);
0310         if (len > *lenp)
0311             len = *lenp;
0312         memcpy(buffer, buf, len);
0313         *lenp = len;
0314         *ppos += len;
0315     }
0316     return 0;
0317 }
0318
0319 static struct ctl_table cmm_table[] = {
0320     {
0321         .procname   = "cmm_pages",
0322         .mode       = 0644,
0323         .proc_handler   = cmm_pages_handler,
0324     },
0325     {
0326         .procname   = "cmm_timed_pages",
0327         .mode       = 0644,
0328         .proc_handler   = cmm_timed_pages_handler,
0329     },
0330     {
0331         .procname   = "cmm_timeout",
0332         .mode       = 0644,
0333         .proc_handler   = cmm_timeout_handler,
0334     },
0335     { }
0336 };
0337
0338 static struct ctl_table cmm_dir_table[] = {
0339     {
0340         .procname   = "vm",
0341         .maxlen     = 0,
0342         .mode       = 0555,
0343         .child      = cmm_table,
0344     },
0345     { }
0346 };
0347
0348 #ifdef CONFIG_CMM_IUCV
0349 #define SMSG_PREFIX "CMM"
0350 static void cmm_smsg_target(const char *from, char *msg)
0351 {
0352     long nr, seconds;
0353
0354     if (strlen(sender) > 0 && strcmp(from, sender) != 0)
0355         return;
0356     if (!cmm_skip_blanks(msg + strlen(SMSG_PREFIX), &msg))
0357         return;
0358     if (strncmp(msg, "SHRINK", 6) == 0) {
0359         if (!cmm_skip_blanks(msg + 6, &msg))
0360             return;
0361         nr = simple_strtoul(msg, &msg, 0);
0362         cmm_skip_blanks(msg, &msg);
0363         if (*msg == '\0')
0364             cmm_set_pages(nr);
0365     } else if (strncmp(msg, "RELEASE", 7) == 0) {
0366         if (!cmm_skip_blanks(msg + 7, &msg))
0367             return;
0368         nr = simple_strtoul(msg, &msg, 0);
0369         cmm_skip_blanks(msg, &msg);
0370         if (*msg == '\0')
0371             cmm_add_timed_pages(nr);
0372     } else if (strncmp(msg, "REUSE", 5) == 0) {
0373         if (!cmm_skip_blanks(msg + 5, &msg))
0374             return;
0375         nr = simple_strtoul(msg, &msg, 0);
0376         if (!cmm_skip_blanks(msg, &msg))
0377             return;
0378         seconds = simple_strtoul(msg, &msg, 0);
0379         cmm_skip_blanks(msg, &msg);
0380         if (*msg == '\0')
0381             cmm_set_timeout(nr, seconds);
0382     }
0383 }
0384 #endif
0385
0386 static struct ctl_table_header *cmm_sysctl_header;
0387
0388 static int __init cmm_init(void)
0389 {
0390     int rc = -ENOMEM;
0391
0392     cmm_sysctl_header = register_sysctl_table(cmm_dir_table);
0393     if (!cmm_sysctl_header)
0394         goto out_sysctl;
0395 #ifdef CONFIG_CMM_IUCV
0396     /* convert sender to uppercase characters */
0397     if (sender)
0398         string_upper(sender, sender);
0399     else
0400         sender = cmm_default_sender;
0401
0402     rc = smsg_register_callback(SMSG_PREFIX, cmm_smsg_target);
0403     if (rc < 0)
0404         goto out_smsg;
0405 #endif
0406     rc = register_oom_notifier(&cmm_oom_nb);
0407     if (rc < 0)
0408         goto out_oom_notify;
0409     cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
0410     if (!IS_ERR(cmm_thread_ptr))
0411         return 0;
0412
0413     rc = PTR_ERR(cmm_thread_ptr);
0414     unregister_oom_notifier(&cmm_oom_nb);
0415 out_oom_notify:
0416 #ifdef CONFIG_CMM_IUCV
0417     smsg_unregister_callback(SMSG_PREFIX, cmm_smsg_target);
0418 out_smsg:
0419 #endif
0420     unregister_sysctl_table(cmm_sysctl_header);
0421 out_sysctl:
0422     del_timer_sync(&cmm_timer);
0423     return rc;
0424 }
0425 module_init(cmm_init);
0426
0427 static void __exit cmm_exit(void)
0428 {
0429     unregister_sysctl_table(cmm_sysctl_header);
0430 #ifdef CONFIG_CMM_IUCV
0431     smsg_unregister_callback(SMSG_PREFIX, cmm_smsg_target);
0432 #endif
0433     unregister_oom_notifier(&cmm_oom_nb);
0434     kthread_stop(cmm_thread_ptr);
0435     del_timer_sync(&cmm_timer);
0436     cmm_free_pages(cmm_pages, &cmm_pages, &cmm_page_list);
0437     cmm_free_pages(cmm_timed_pages, &cmm_timed_pages, &cmm_timed_page_list);
0438 }
0439 module_exit(cmm_exit);
0440
0441 MODULE_LICENSE("GPL");