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