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