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