linux/drivers/xen/tmem.c
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   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
  45struct tmem_pool_uuid {
  46        u64 uuid_lo;
  47        u64 uuid_hi;
  48};
  49
  50struct 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
  62static 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
  82static 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
 102static 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
 111static 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
 120static 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
 126static 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
 131bool __read_mostly tmem_enabled = false;
 132
 133static 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
 141static 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
 150static 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
 165static 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
 185static 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
 198static 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
 207static void tmem_cleancache_flush_fs(int pool)
 208{
 209        if (pool < 0)
 210                return;
 211        (void)xen_tmem_destroy_pool((u32)pool);
 212}
 213
 214static 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
 221static 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
 230static bool __initdata use_cleancache = true;
 231
 232static int __init no_cleancache(char *s)
 233{
 234        use_cleancache = false;
 235        return 1;
 236}
 237__setup("nocleancache", no_cleancache);
 238
 239static 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) */
 254static 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
 265static 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 */
 273static 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 */
 299static 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 */
 321static 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 */
 335static 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
 346static 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
 356static bool __initdata use_frontswap = true;
 357
 358static int __init no_frontswap(char *s)
 359{
 360        use_frontswap = false;
 361        return 1;
 362}
 363__setup("nofrontswap", no_frontswap);
 364
 365static 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
 374static 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\n");
 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
 406module_init(xen_tmem_init)
 407
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