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
  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
  44struct tmem_pool_uuid {
  45        u64 uuid_lo;
  46        u64 uuid_hi;
  47};
  48
  49struct 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
  61static 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
  81static 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
 101static 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
 110static 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
 119static 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
 125static 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
 130bool __read_mostly tmem_enabled = false;
 131
 132static 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
 140static 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
 149static 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
 164static 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
 184static 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
 197static 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
 206static void tmem_cleancache_flush_fs(int pool)
 207{
 208        if (pool < 0)
 209                return;
 210        (void)xen_tmem_destroy_pool((u32)pool);
 211}
 212
 213static 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
 220static 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
 229static bool __initdata use_cleancache = true;
 230
 231static int __init no_cleancache(char *s)
 232{
 233        use_cleancache = false;
 234        return 1;
 235}
 236__setup("nocleancache", no_cleancache);
 237
 238static 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) */
 253static 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
 264static 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 */
 272static int tmem_frontswap_store(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 */
 298static int tmem_frontswap_load(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 */
 320static 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 */
 334static 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
 345static 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
 355static bool __initdata use_frontswap = true;
 356
 357static int __init no_frontswap(char *s)
 358{
 359        use_frontswap = false;
 360        return 1;
 361}
 362__setup("nofrontswap", no_frontswap);
 363
 364static struct frontswap_ops __initdata tmem_frontswap_ops = {
 365        .store = tmem_frontswap_store,
 366        .load = tmem_frontswap_load,
 367        .invalidate_page = tmem_frontswap_flush_page,
 368        .invalidate_area = tmem_frontswap_flush_area,
 369        .init = tmem_frontswap_init
 370};
 371#endif
 372
 373static 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
 405module_init(xen_tmem_init)
 406
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