drivers/xen/tmem.c

   1 /*
   2  * Xen implementation for transcendent memory (tmem)
   3  *
   4  * Copyright (C) 2009-2011 Oracle Corp.  All rights reserved.
   5  * Author: Dan Magenheimer
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/kernel.h>
  10 #include <linux/types.h>
  11 #include <linux/init.h>
  12 #include <linux/pagemap.h>
  13 #include <linux/cleancache.h>
  14 #include <linux/frontswap.h>
  15
  16 #include <xen/xen.h>
  17 #include <xen/interface/xen.h>
  18 #include <asm/xen/hypercall.h>
  19 #include <asm/xen/page.h>
  20 #include <asm/xen/hypervisor.h>
  21 #include <xen/tmem.h>
  22
  23 #ifndef CONFIG_XEN_TMEM_MODULE
  24 bool __read_mostly tmem_enabled = false;
  25
  26 static int __init enable_tmem(char *s)
  27 {
  28         tmem_enabled = true;
  29         return 1;
  30 }
  31 __setup("tmem", enable_tmem);
  32 #endif
  33
  34 #ifdef CONFIG_CLEANCACHE
  35 static bool disable_cleancache __read_mostly;
  36 static bool disable_selfballooning __read_mostly;
  37 #ifdef CONFIG_XEN_TMEM_MODULE
  38 module_param(disable_cleancache, bool, S_IRUGO);
  39 module_param(disable_selfballooning, bool, S_IRUGO);
  40 #else
  41 static int __init no_cleancache(char *s)
  42 {
  43         disable_cleancache = true;
  44         return 1;
  45 }
  46 __setup("nocleancache", no_cleancache);
  47 #endif
  48 #endif /* CONFIG_CLEANCACHE */
  49
  50 #ifdef CONFIG_FRONTSWAP
  51 static bool disable_frontswap __read_mostly;
  52 #ifdef CONFIG_XEN_TMEM_MODULE
  53 module_param(disable_frontswap, bool, S_IRUGO);
  54 #else
  55 static int __init no_frontswap(char *s)
  56 {
  57         disable_frontswap = true;
  58         return 1;
  59 }
  60 __setup("nofrontswap", no_frontswap);
  61 #endif
  62 #endif /* CONFIG_FRONTSWAP */
  63
  64 #ifdef CONFIG_FRONTSWAP
  65 static bool disable_frontswap_selfshrinking __read_mostly;
  66 #ifdef CONFIG_XEN_TMEM_MODULE
  67 module_param(disable_frontswap_selfshrinking, bool, S_IRUGO);
  68 #else
  69 #define disable_frontswap_selfshrinking 1
  70 #endif
  71 #endif /* CONFIG_FRONTSWAP */
  72
  73 #define TMEM_CONTROL               0
  74 #define TMEM_NEW_POOL              1
  75 #define TMEM_DESTROY_POOL          2
  76 #define TMEM_NEW_PAGE              3
  77 #define TMEM_PUT_PAGE              4
  78 #define TMEM_GET_PAGE              5
  79 #define TMEM_FLUSH_PAGE            6
  80 #define TMEM_FLUSH_OBJECT          7
  81 #define TMEM_READ                  8
  82 #define TMEM_WRITE                 9
  83 #define TMEM_XCHG                 10
  84
  85 /* Bits for HYPERVISOR_tmem_op(TMEM_NEW_POOL) */
  86 #define TMEM_POOL_PERSIST          1
  87 #define TMEM_POOL_SHARED           2
  88 #define TMEM_POOL_PAGESIZE_SHIFT   4
  89 #define TMEM_VERSION_SHIFT        24
  90
  91
  92 struct tmem_pool_uuid {
  93         u64 uuid_lo;
  94         u64 uuid_hi;
  95 };
  96
  97 struct tmem_oid {
  98         u64 oid[3];
  99 };
 100
 101 #define TMEM_POOL_PRIVATE_UUID  { 0, 0 }
 102
 103 /* flags for tmem_ops.new_pool */
 104 #define TMEM_POOL_PERSIST          1
 105 #define TMEM_POOL_SHARED           2
 106
 107 /* xen tmem foundation ops/hypercalls */
 108
 109 static inline int xen_tmem_op(u32 tmem_cmd, u32 tmem_pool, struct tmem_oid oid,
 110         u32 index, unsigned long gmfn, u32 tmem_offset, u32 pfn_offset, u32 len)
 111 {
 112         struct tmem_op op;
 113         int rc = 0;
 114
 115         op.cmd = tmem_cmd;
 116         op.pool_id = tmem_pool;
 117         op.u.gen.oid[0] = oid.oid[0];
 118         op.u.gen.oid[1] = oid.oid[1];
 119         op.u.gen.oid[2] = oid.oid[2];
 120         op.u.gen.index = index;
 121         op.u.gen.tmem_offset = tmem_offset;
 122         op.u.gen.pfn_offset = pfn_offset;
 123         op.u.gen.len = len;
 124         set_xen_guest_handle(op.u.gen.gmfn, (void *)gmfn);
 125         rc = HYPERVISOR_tmem_op(&op);
 126         return rc;
 127 }
 128
 129 static int xen_tmem_new_pool(struct tmem_pool_uuid uuid,
 130                                 u32 flags, unsigned long pagesize)
 131 {
 132         struct tmem_op op;
 133         int rc = 0, pageshift;
 134
 135         for (pageshift = 0; pagesize != 1; pageshift++)
 136                 pagesize >>= 1;
 137         flags |= (pageshift - 12) << TMEM_POOL_PAGESIZE_SHIFT;
 138         flags |= TMEM_SPEC_VERSION << TMEM_VERSION_SHIFT;
 139         op.cmd = TMEM_NEW_POOL;
 140         op.u.new.uuid[0] = uuid.uuid_lo;
 141         op.u.new.uuid[1] = uuid.uuid_hi;
 142         op.u.new.flags = flags;
 143         rc = HYPERVISOR_tmem_op(&op);
 144         return rc;
 145 }
 146
 147 /* xen generic tmem ops */
 148
 149 static int xen_tmem_put_page(u32 pool_id, struct tmem_oid oid,
 150                              u32 index, unsigned long pfn)
 151 {
 152         unsigned long gmfn = xen_pv_domain() ? pfn_to_mfn(pfn) : pfn;
 153
 154         return xen_tmem_op(TMEM_PUT_PAGE, pool_id, oid, index,
 155                 gmfn, 0, 0, 0);
 156 }
 157
 158 static int xen_tmem_get_page(u32 pool_id, struct tmem_oid oid,
 159                              u32 index, unsigned long pfn)
 160 {
 161         unsigned long gmfn = xen_pv_domain() ? pfn_to_mfn(pfn) : pfn;
 162
 163         return xen_tmem_op(TMEM_GET_PAGE, pool_id, oid, index,
 164                 gmfn, 0, 0, 0);
 165 }
 166
 167 static int xen_tmem_flush_page(u32 pool_id, struct tmem_oid oid, u32 index)
 168 {
 169         return xen_tmem_op(TMEM_FLUSH_PAGE, pool_id, oid, index,
 170                 0, 0, 0, 0);
 171 }
 172
 173 static int xen_tmem_flush_object(u32 pool_id, struct tmem_oid oid)
 174 {
 175         return xen_tmem_op(TMEM_FLUSH_OBJECT, pool_id, oid, 0, 0, 0, 0, 0);
 176 }
 177
 178
 179 #ifdef CONFIG_CLEANCACHE
 180 static int xen_tmem_destroy_pool(u32 pool_id)
 181 {
 182         struct tmem_oid oid = { { 0 } };
 183
 184         return xen_tmem_op(TMEM_DESTROY_POOL, pool_id, oid, 0, 0, 0, 0, 0);
 185 }
 186
 187 /* cleancache ops */
 188
 189 static void tmem_cleancache_put_page(int pool, struct cleancache_filekey key,
 190                                      pgoff_t index, struct page *page)
 191 {
 192         u32 ind = (u32) index;
 193         struct tmem_oid oid = *(struct tmem_oid *)&key;
 194         unsigned long pfn = page_to_pfn(page);
 195
 196         if (pool < 0)
 197                 return;
 198         if (ind != index)
 199                 return;
 200         mb(); /* ensure page is quiescent; tmem may address it with an alias */
 201         (void)xen_tmem_put_page((u32)pool, oid, ind, pfn);
 202 }
 203
 204 static int tmem_cleancache_get_page(int pool, struct cleancache_filekey key,
 205                                     pgoff_t index, struct page *page)
 206 {
 207         u32 ind = (u32) index;
 208         struct tmem_oid oid = *(struct tmem_oid *)&key;
 209         unsigned long pfn = page_to_pfn(page);
 210         int ret;
 211
 212         /* translate return values to linux semantics */
 213         if (pool < 0)
 214                 return -1;
 215         if (ind != index)
 216                 return -1;
 217         ret = xen_tmem_get_page((u32)pool, oid, ind, pfn);
 218         if (ret == 1)
 219                 return 0;
 220         else
 221                 return -1;
 222 }
 223
 224 static void tmem_cleancache_flush_page(int pool, struct cleancache_filekey key,
 225                                        pgoff_t index)
 226 {
 227         u32 ind = (u32) index;
 228         struct tmem_oid oid = *(struct tmem_oid *)&key;
 229
 230         if (pool < 0)
 231                 return;
 232         if (ind != index)
 233                 return;
 234         (void)xen_tmem_flush_page((u32)pool, oid, ind);
 235 }
 236
 237 static void tmem_cleancache_flush_inode(int pool, struct cleancache_filekey key)
 238 {
 239         struct tmem_oid oid = *(struct tmem_oid *)&key;
 240
 241         if (pool < 0)
 242                 return;
 243         (void)xen_tmem_flush_object((u32)pool, oid);
 244 }
 245
 246 static void tmem_cleancache_flush_fs(int pool)
 247 {
 248         if (pool < 0)
 249                 return;
 250         (void)xen_tmem_destroy_pool((u32)pool);
 251 }
 252
 253 static int tmem_cleancache_init_fs(size_t pagesize)
 254 {
 255         struct tmem_pool_uuid uuid_private = TMEM_POOL_PRIVATE_UUID;
 256
 257         return xen_tmem_new_pool(uuid_private, 0, pagesize);
 258 }
 259
 260 static int tmem_cleancache_init_shared_fs(char *uuid, size_t pagesize)
 261 {
 262         struct tmem_pool_uuid shared_uuid;
 263
 264         shared_uuid.uuid_lo = *(u64 *)uuid;
 265         shared_uuid.uuid_hi = *(u64 *)(&uuid[8]);
 266         return xen_tmem_new_pool(shared_uuid, TMEM_POOL_SHARED, pagesize);
 267 }
 268
 269 static struct cleancache_ops tmem_cleancache_ops = {
 270         .put_page = tmem_cleancache_put_page,
 271         .get_page = tmem_cleancache_get_page,
 272         .invalidate_page = tmem_cleancache_flush_page,
 273         .invalidate_inode = tmem_cleancache_flush_inode,
 274         .invalidate_fs = tmem_cleancache_flush_fs,
 275         .init_shared_fs = tmem_cleancache_init_shared_fs,
 276         .init_fs = tmem_cleancache_init_fs
 277 };
 278 #endif
 279
 280 #ifdef CONFIG_FRONTSWAP
 281 /* frontswap tmem operations */
 282
 283 /* a single tmem poolid is used for all frontswap "types" (swapfiles) */
 284 static int tmem_frontswap_poolid;
 285
 286 /*
 287  * Swizzling increases objects per swaptype, increasing tmem concurrency
 288  * for heavy swaploads.  Later, larger nr_cpus -> larger SWIZ_BITS
 289  */
 290 #define SWIZ_BITS               4
 291 #define SWIZ_MASK               ((1 << SWIZ_BITS) - 1)
 292 #define _oswiz(_type, _ind)     ((_type << SWIZ_BITS) | (_ind & SWIZ_MASK))
 293 #define iswiz(_ind)             (_ind >> SWIZ_BITS)
 294
 295 static inline struct tmem_oid oswiz(unsigned type, u32 ind)
 296 {
 297         struct tmem_oid oid = { .oid = { 0 } };
 298         oid.oid[0] = _oswiz(type, ind);
 299         return oid;
 300 }
 301
 302 /* returns 0 if the page was successfully put into frontswap, -1 if not */
 303 static int tmem_frontswap_store(unsigned type, pgoff_t offset,
 304                                    struct page *page)
 305 {
 306         u64 ind64 = (u64)offset;
 307         u32 ind = (u32)offset;
 308         unsigned long pfn = page_to_pfn(page);
 309         int pool = tmem_frontswap_poolid;
 310         int ret;
 311
 312         if (pool < 0)
 313                 return -1;
 314         if (ind64 != ind)
 315                 return -1;
 316         mb(); /* ensure page is quiescent; tmem may address it with an alias */
 317         ret = xen_tmem_put_page(pool, oswiz(type, ind), iswiz(ind), pfn);
 318         /* translate Xen tmem return values to linux semantics */
 319         if (ret == 1)
 320                 return 0;
 321         else
 322                 return -1;
 323 }
 324
 325 /*
 326  * returns 0 if the page was successfully gotten from frontswap, -1 if
 327  * was not present (should never happen!)
 328  */
 329 static int tmem_frontswap_load(unsigned type, pgoff_t offset,
 330                                    struct page *page)
 331 {
 332         u64 ind64 = (u64)offset;
 333         u32 ind = (u32)offset;
 334         unsigned long pfn = page_to_pfn(page);
 335         int pool = tmem_frontswap_poolid;
 336         int ret;
 337
 338         if (pool < 0)
 339                 return -1;
 340         if (ind64 != ind)
 341                 return -1;
 342         ret = xen_tmem_get_page(pool, oswiz(type, ind), iswiz(ind), pfn);
 343         /* translate Xen tmem return values to linux semantics */
 344         if (ret == 1)
 345                 return 0;
 346         else
 347                 return -1;
 348 }
 349
 350 /* flush a single page from frontswap */
 351 static void tmem_frontswap_flush_page(unsigned type, pgoff_t offset)
 352 {
 353         u64 ind64 = (u64)offset;
 354         u32 ind = (u32)offset;
 355         int pool = tmem_frontswap_poolid;
 356
 357         if (pool < 0)
 358                 return;
 359         if (ind64 != ind)
 360                 return;
 361         (void) xen_tmem_flush_page(pool, oswiz(type, ind), iswiz(ind));
 362 }
 363
 364 /* flush all pages from the passed swaptype */
 365 static void tmem_frontswap_flush_area(unsigned type)
 366 {
 367         int pool = tmem_frontswap_poolid;
 368         int ind;
 369
 370         if (pool < 0)
 371                 return;
 372         for (ind = SWIZ_MASK; ind >= 0; ind--)
 373                 (void)xen_tmem_flush_object(pool, oswiz(type, ind));
 374 }
 375
 376 static void tmem_frontswap_init(unsigned ignored)
 377 {
 378         struct tmem_pool_uuid private = TMEM_POOL_PRIVATE_UUID;
 379
 380         /* a single tmem poolid is used for all frontswap "types" (swapfiles) */
 381         if (tmem_frontswap_poolid < 0)
 382                 tmem_frontswap_poolid =
 383                     xen_tmem_new_pool(private, TMEM_POOL_PERSIST, PAGE_SIZE);
 384 }
 385
 386 static struct frontswap_ops tmem_frontswap_ops = {
 387         .store = tmem_frontswap_store,
 388         .load = tmem_frontswap_load,
 389         .invalidate_page = tmem_frontswap_flush_page,
 390         .invalidate_area = tmem_frontswap_flush_area,
 391         .init = tmem_frontswap_init
 392 };
 393 #endif
 394
 395 static int xen_tmem_init(void)
 396 {
 397         if (!xen_domain())
 398                 return 0;
 399 #ifdef CONFIG_FRONTSWAP
 400         if (tmem_enabled && !disable_frontswap) {
 401                 char *s = "";
 402                 struct frontswap_ops *old_ops =
 403                         frontswap_register_ops(&tmem_frontswap_ops);
 404
 405                 tmem_frontswap_poolid = -1;
 406                 if (IS_ERR(old_ops) || old_ops) {
 407                         if (IS_ERR(old_ops))
 408                                 return PTR_ERR(old_ops);
 409                         s = " (WARNING: frontswap_ops overridden)";
 410                 }
 411                 printk(KERN_INFO "frontswap enabled, RAM provided by "
 412                                  "Xen Transcendent Memory%s\n", s);
 413         }
 414 #endif
 415 #ifdef CONFIG_CLEANCACHE
 416         BUG_ON(sizeof(struct cleancache_filekey) != sizeof(struct tmem_oid));
 417         if (tmem_enabled && !disable_cleancache) {
 418                 char *s = "";
 419                 struct cleancache_ops *old_ops =
 420                         cleancache_register_ops(&tmem_cleancache_ops);
 421                 if (old_ops)
 422                         s = " (WARNING: cleancache_ops overridden)";
 423                 printk(KERN_INFO "cleancache enabled, RAM provided by "
 424                                  "Xen Transcendent Memory%s\n", s);
 425         }
 426 #endif
 427 #ifdef CONFIG_XEN_SELFBALLOONING
 428         xen_selfballoon_init(!disable_selfballooning,
 429                                 !disable_frontswap_selfshrinking);
 430 #endif
 431         return 0;
 432 }
 433
 434 module_init(xen_tmem_init)
 435 MODULE_LICENSE("GPL");
 436 MODULE_AUTHOR("Dan Magenheimer <dan.magenheimer@oracle.com>");
 437 MODULE_DESCRIPTION("Shim to Xen transcendent memory");