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 <asm/xen/hypercall.h>
  21 #include <asm/xen/page.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, unsigned long pfn)
 133 {
 134         unsigned long gmfn = xen_pv_domain() ? pfn_to_mfn(pfn) : pfn;
 135
 136         return xen_tmem_op(TMEM_PUT_PAGE, pool_id, oid, index,
 137                 gmfn, 0, 0, 0);
 138 }
 139
 140 static int xen_tmem_get_page(u32 pool_id, struct tmem_oid oid,
 141                              u32 index, unsigned long pfn)
 142 {
 143         unsigned long gmfn = xen_pv_domain() ? pfn_to_mfn(pfn) : pfn;
 144
 145         return xen_tmem_op(TMEM_GET_PAGE, pool_id, oid, index,
 146                 gmfn, 0, 0, 0);
 147 }
 148
 149 static int xen_tmem_flush_page(u32 pool_id, struct tmem_oid oid, u32 index)
 150 {
 151         return xen_tmem_op(TMEM_FLUSH_PAGE, pool_id, oid, index,
 152                 0, 0, 0, 0);
 153 }
 154
 155 static int xen_tmem_flush_object(u32 pool_id, struct tmem_oid oid)
 156 {
 157         return xen_tmem_op(TMEM_FLUSH_OBJECT, pool_id, oid, 0, 0, 0, 0, 0);
 158 }
 159
 160
 161 #ifdef CONFIG_CLEANCACHE
 162 static int xen_tmem_destroy_pool(u32 pool_id)
 163 {
 164         struct tmem_oid oid = { { 0 } };
 165
 166         return xen_tmem_op(TMEM_DESTROY_POOL, pool_id, oid, 0, 0, 0, 0, 0);
 167 }
 168
 169 /* cleancache ops */
 170
 171 static void tmem_cleancache_put_page(int pool, struct cleancache_filekey key,
 172                                      pgoff_t index, struct page *page)
 173 {
 174         u32 ind = (u32) index;
 175         struct tmem_oid oid = *(struct tmem_oid *)&key;
 176         unsigned long pfn = page_to_pfn(page);
 177
 178         if (pool < 0)
 179                 return;
 180         if (ind != index)
 181                 return;
 182         mb(); /* ensure page is quiescent; tmem may address it with an alias */
 183         (void)xen_tmem_put_page((u32)pool, oid, ind, pfn);
 184 }
 185
 186 static int tmem_cleancache_get_page(int pool, struct cleancache_filekey key,
 187                                     pgoff_t index, struct page *page)
 188 {
 189         u32 ind = (u32) index;
 190         struct tmem_oid oid = *(struct tmem_oid *)&key;
 191         unsigned long pfn = page_to_pfn(page);
 192         int ret;
 193
 194         /* translate return values to linux semantics */
 195         if (pool < 0)
 196                 return -1;
 197         if (ind != index)
 198                 return -1;
 199         ret = xen_tmem_get_page((u32)pool, oid, ind, pfn);
 200         if (ret == 1)
 201                 return 0;
 202         else
 203                 return -1;
 204 }
 205
 206 static void tmem_cleancache_flush_page(int pool, struct cleancache_filekey key,
 207                                        pgoff_t index)
 208 {
 209         u32 ind = (u32) index;
 210         struct tmem_oid oid = *(struct tmem_oid *)&key;
 211
 212         if (pool < 0)
 213                 return;
 214         if (ind != index)
 215                 return;
 216         (void)xen_tmem_flush_page((u32)pool, oid, ind);
 217 }
 218
 219 static void tmem_cleancache_flush_inode(int pool, struct cleancache_filekey key)
 220 {
 221         struct tmem_oid oid = *(struct tmem_oid *)&key;
 222
 223         if (pool < 0)
 224                 return;
 225         (void)xen_tmem_flush_object((u32)pool, oid);
 226 }
 227
 228 static void tmem_cleancache_flush_fs(int pool)
 229 {
 230         if (pool < 0)
 231                 return;
 232         (void)xen_tmem_destroy_pool((u32)pool);
 233 }
 234
 235 static int tmem_cleancache_init_fs(size_t pagesize)
 236 {
 237         struct tmem_pool_uuid uuid_private = TMEM_POOL_PRIVATE_UUID;
 238
 239         return xen_tmem_new_pool(uuid_private, 0, pagesize);
 240 }
 241
 242 static int tmem_cleancache_init_shared_fs(char *uuid, size_t pagesize)
 243 {
 244         struct tmem_pool_uuid shared_uuid;
 245
 246         shared_uuid.uuid_lo = *(u64 *)uuid;
 247         shared_uuid.uuid_hi = *(u64 *)(&uuid[8]);
 248         return xen_tmem_new_pool(shared_uuid, TMEM_POOL_SHARED, pagesize);
 249 }
 250
 251 static struct cleancache_ops tmem_cleancache_ops = {
 252         .put_page = tmem_cleancache_put_page,
 253         .get_page = tmem_cleancache_get_page,
 254         .invalidate_page = tmem_cleancache_flush_page,
 255         .invalidate_inode = tmem_cleancache_flush_inode,
 256         .invalidate_fs = tmem_cleancache_flush_fs,
 257         .init_shared_fs = tmem_cleancache_init_shared_fs,
 258         .init_fs = tmem_cleancache_init_fs
 259 };
 260 #endif
 261
 262 #ifdef CONFIG_FRONTSWAP
 263 /* frontswap tmem operations */
 264
 265 /* a single tmem poolid is used for all frontswap "types" (swapfiles) */
 266 static int tmem_frontswap_poolid;
 267
 268 /*
 269  * Swizzling increases objects per swaptype, increasing tmem concurrency
 270  * for heavy swaploads.  Later, larger nr_cpus -> larger SWIZ_BITS
 271  */
 272 #define SWIZ_BITS               4
 273 #define SWIZ_MASK               ((1 << SWIZ_BITS) - 1)
 274 #define _oswiz(_type, _ind)     ((_type << SWIZ_BITS) | (_ind & SWIZ_MASK))
 275 #define iswiz(_ind)             (_ind >> SWIZ_BITS)
 276
 277 static inline struct tmem_oid oswiz(unsigned type, u32 ind)
 278 {
 279         struct tmem_oid oid = { .oid = { 0 } };
 280         oid.oid[0] = _oswiz(type, ind);
 281         return oid;
 282 }
 283
 284 /* returns 0 if the page was successfully put into frontswap, -1 if not */
 285 static int tmem_frontswap_store(unsigned type, pgoff_t offset,
 286                                    struct page *page)
 287 {
 288         u64 ind64 = (u64)offset;
 289         u32 ind = (u32)offset;
 290         unsigned long pfn = page_to_pfn(page);
 291         int pool = tmem_frontswap_poolid;
 292         int ret;
 293
 294         if (pool < 0)
 295                 return -1;
 296         if (ind64 != ind)
 297                 return -1;
 298         mb(); /* ensure page is quiescent; tmem may address it with an alias */
 299         ret = xen_tmem_put_page(pool, oswiz(type, ind), iswiz(ind), pfn);
 300         /* translate Xen tmem return values to linux semantics */
 301         if (ret == 1)
 302                 return 0;
 303         else
 304                 return -1;
 305 }
 306
 307 /*
 308  * returns 0 if the page was successfully gotten from frontswap, -1 if
 309  * was not present (should never happen!)
 310  */
 311 static int tmem_frontswap_load(unsigned type, pgoff_t offset,
 312                                    struct page *page)
 313 {
 314         u64 ind64 = (u64)offset;
 315         u32 ind = (u32)offset;
 316         unsigned long pfn = page_to_pfn(page);
 317         int pool = tmem_frontswap_poolid;
 318         int ret;
 319
 320         if (pool < 0)
 321                 return -1;
 322         if (ind64 != ind)
 323                 return -1;
 324         ret = xen_tmem_get_page(pool, oswiz(type, ind), iswiz(ind), pfn);
 325         /* translate Xen tmem return values to linux semantics */
 326         if (ret == 1)
 327                 return 0;
 328         else
 329                 return -1;
 330 }
 331
 332 /* flush a single page from frontswap */
 333 static void tmem_frontswap_flush_page(unsigned type, pgoff_t offset)
 334 {
 335         u64 ind64 = (u64)offset;
 336         u32 ind = (u32)offset;
 337         int pool = tmem_frontswap_poolid;
 338
 339         if (pool < 0)
 340                 return;
 341         if (ind64 != ind)
 342                 return;
 343         (void) xen_tmem_flush_page(pool, oswiz(type, ind), iswiz(ind));
 344 }
 345
 346 /* flush all pages from the passed swaptype */
 347 static void tmem_frontswap_flush_area(unsigned type)
 348 {
 349         int pool = tmem_frontswap_poolid;
 350         int ind;
 351
 352         if (pool < 0)
 353                 return;
 354         for (ind = SWIZ_MASK; ind >= 0; ind--)
 355                 (void)xen_tmem_flush_object(pool, oswiz(type, ind));
 356 }
 357
 358 static void tmem_frontswap_init(unsigned ignored)
 359 {
 360         struct tmem_pool_uuid private = TMEM_POOL_PRIVATE_UUID;
 361
 362         /* a single tmem poolid is used for all frontswap "types" (swapfiles) */
 363         if (tmem_frontswap_poolid < 0)
 364                 tmem_frontswap_poolid =
 365                     xen_tmem_new_pool(private, TMEM_POOL_PERSIST, PAGE_SIZE);
 366 }
 367
 368 static struct frontswap_ops tmem_frontswap_ops = {
 369         .store = tmem_frontswap_store,
 370         .load = tmem_frontswap_load,
 371         .invalidate_page = tmem_frontswap_flush_page,
 372         .invalidate_area = tmem_frontswap_flush_area,
 373         .init = tmem_frontswap_init
 374 };
 375 #endif
 376
 377 static int __init xen_tmem_init(void)
 378 {
 379         if (!xen_domain())
 380                 return 0;
 381 #ifdef CONFIG_FRONTSWAP
 382         if (tmem_enabled && frontswap) {
 383                 char *s = "";
 384                 struct frontswap_ops *old_ops;
 385
 386                 tmem_frontswap_poolid = -1;
 387                 old_ops = frontswap_register_ops(&tmem_frontswap_ops);
 388                 if (IS_ERR(old_ops) || old_ops) {
 389                         if (IS_ERR(old_ops))
 390                                 return PTR_ERR(old_ops);
 391                         s = " (WARNING: frontswap_ops overridden)";
 392                 }
 393                 pr_info("frontswap enabled, RAM provided by Xen Transcendent Memory%s\n",
 394                         s);
 395         }
 396 #endif
 397 #ifdef CONFIG_CLEANCACHE
 398         BUG_ON(sizeof(struct cleancache_filekey) != sizeof(struct tmem_oid));
 399         if (tmem_enabled && cleancache) {
 400                 int err;
 401
 402                 err = cleancache_register_ops(&tmem_cleancache_ops);
 403                 if (err)
 404                         pr_warn("xen-tmem: failed to enable cleancache: %d\n",
 405                                 err);
 406                 else
 407                         pr_info("cleancache enabled, RAM provided by "
 408                                 "Xen Transcendent Memory\n");
 409         }
 410 #endif
 411 #ifdef CONFIG_XEN_SELFBALLOONING
 412         /*
 413          * There is no point of driving pages to the swap system if they
 414          * aren't going anywhere in tmem universe.
 415          */
 416         if (!frontswap) {
 417                 selfshrinking = false;
 418                 selfballooning = false;
 419         }
 420         xen_selfballoon_init(selfballooning, selfshrinking);
 421 #endif
 422         return 0;
 423 }
 424
 425 module_init(xen_tmem_init)
 426 MODULE_LICENSE("GPL");
 427 MODULE_AUTHOR("Dan Magenheimer <dan.magenheimer@oracle.com>");
 428 MODULE_DESCRIPTION("Shim to Xen transcendent memory");