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