drivers/xen/tmem.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Xen implementation for transcendent memory (tmem)
   4  *
   5  * Copyright (C) 2009-2011 Oracle Corp.  All rights reserved.
   6  * Author: Dan Magenheimer
   7  */
   8
   9 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
  10
  11 #include <linux/module.h>
  12 #include <linux/kernel.h>
  13 #include <linux/types.h>
  14 #include <linux/init.h>
  15 #include <linux/pagemap.h>
  16 #include <linux/cleancache.h>
  17 #include <linux/frontswap.h>
  18
  19 #include <xen/xen.h>
  20 #include <xen/interface/xen.h>
  21 #include <xen/page.h>
  22 #include <asm/xen/hypercall.h>
  23 #include <asm/xen/hypervisor.h>
  24 #include <xen/tmem.h>
  25
  26 #ifndef CONFIG_XEN_TMEM_MODULE
  27 bool __read_mostly tmem_enabled = false;
  28
  29 static int __init enable_tmem(char *s)
  30 {
  31         tmem_enabled = true;
  32         return 1;
  33 }
  34 __setup("tmem", enable_tmem);
  35 #endif
  36
  37 #ifdef CONFIG_CLEANCACHE
  38 static bool cleancache __read_mostly = true;
  39 module_param(cleancache, bool, S_IRUGO);
  40 static bool selfballooning __read_mostly = true;
  41 module_param(selfballooning, bool, S_IRUGO);
  42 #endif /* CONFIG_CLEANCACHE */
  43
  44 #ifdef CONFIG_FRONTSWAP
  45 static bool frontswap __read_mostly = true;
  46 module_param(frontswap, bool, S_IRUGO);
  47 #else /* CONFIG_FRONTSWAP */
  48 #define frontswap (0)
  49 #endif /* CONFIG_FRONTSWAP */
  50
  51 #ifdef CONFIG_XEN_SELFBALLOONING
  52 static bool selfshrinking __read_mostly = true;
  53 module_param(selfshrinking, bool, S_IRUGO);
  54 #endif /* CONFIG_XEN_SELFBALLOONING */
  55
  56 #define TMEM_CONTROL               0
  57 #define TMEM_NEW_POOL              1
  58 #define TMEM_DESTROY_POOL          2
  59 #define TMEM_NEW_PAGE              3
  60 #define TMEM_PUT_PAGE              4
  61 #define TMEM_GET_PAGE              5
  62 #define TMEM_FLUSH_PAGE            6
  63 #define TMEM_FLUSH_OBJECT          7
  64 #define TMEM_READ                  8
  65 #define TMEM_WRITE                 9
  66 #define TMEM_XCHG                 10
  67
  68 /* Bits for HYPERVISOR_tmem_op(TMEM_NEW_POOL) */
  69 #define TMEM_POOL_PERSIST          1
  70 #define TMEM_POOL_SHARED           2
  71 #define TMEM_POOL_PAGESIZE_SHIFT   4
  72 #define TMEM_VERSION_SHIFT        24
  73
  74
  75 struct tmem_pool_uuid {
  76         u64 uuid_lo;
  77         u64 uuid_hi;
  78 };
  79
  80 struct tmem_oid {
  81         u64 oid[3];
  82 };
  83
  84 #define TMEM_POOL_PRIVATE_UUID  { 0, 0 }
  85
  86 /* flags for tmem_ops.new_pool */
  87 #define TMEM_POOL_PERSIST          1
  88 #define TMEM_POOL_SHARED           2
  89
  90 /* xen tmem foundation ops/hypercalls */
  91
  92 static inline int xen_tmem_op(u32 tmem_cmd, u32 tmem_pool, struct tmem_oid oid,
  93         u32 index, unsigned long gmfn, u32 tmem_offset, u32 pfn_offset, u32 len)
  94 {
  95         struct tmem_op op;
  96         int rc = 0;
  97
  98         op.cmd = tmem_cmd;
  99         op.pool_id = tmem_pool;
 100         op.u.gen.oid[0] = oid.oid[0];
 101         op.u.gen.oid[1] = oid.oid[1];
 102         op.u.gen.oid[2] = oid.oid[2];
 103         op.u.gen.index = index;
 104         op.u.gen.tmem_offset = tmem_offset;
 105         op.u.gen.pfn_offset = pfn_offset;
 106         op.u.gen.len = len;
 107         set_xen_guest_handle(op.u.gen.gmfn, (void *)gmfn);
 108         rc = HYPERVISOR_tmem_op(&op);
 109         return rc;
 110 }
 111
 112 static int xen_tmem_new_pool(struct tmem_pool_uuid uuid,
 113                                 u32 flags, unsigned long pagesize)
 114 {
 115         struct tmem_op op;
 116         int rc = 0, pageshift;
 117
 118         for (pageshift = 0; pagesize != 1; pageshift++)
 119                 pagesize >>= 1;
 120         flags |= (pageshift - 12) << TMEM_POOL_PAGESIZE_SHIFT;
 121         flags |= TMEM_SPEC_VERSION << TMEM_VERSION_SHIFT;
 122         op.cmd = TMEM_NEW_POOL;
 123         op.u.new.uuid[0] = uuid.uuid_lo;
 124         op.u.new.uuid[1] = uuid.uuid_hi;
 125         op.u.new.flags = flags;
 126         rc = HYPERVISOR_tmem_op(&op);
 127         return rc;
 128 }
 129
 130 /* xen generic tmem ops */
 131
 132 static int xen_tmem_put_page(u32 pool_id, struct tmem_oid oid,
 133                              u32 index, struct page *page)
 134 {
 135         return xen_tmem_op(TMEM_PUT_PAGE, pool_id, oid, index,
 136                            xen_page_to_gfn(page), 0, 0, 0);
 137 }
 138
 139 static int xen_tmem_get_page(u32 pool_id, struct tmem_oid oid,
 140                              u32 index, struct page *page)
 141 {
 142         return xen_tmem_op(TMEM_GET_PAGE, pool_id, oid, index,
 143                            xen_page_to_gfn(page), 0, 0, 0);
 144 }
 145
 146 static int xen_tmem_flush_page(u32 pool_id, struct tmem_oid oid, u32 index)
 147 {
 148         return xen_tmem_op(TMEM_FLUSH_PAGE, pool_id, oid, index,
 149                 0, 0, 0, 0);
 150 }
 151
 152 static int xen_tmem_flush_object(u32 pool_id, struct tmem_oid oid)
 153 {
 154         return xen_tmem_op(TMEM_FLUSH_OBJECT, pool_id, oid, 0, 0, 0, 0, 0);
 155 }
 156
 157
 158 #ifdef CONFIG_CLEANCACHE
 159 static int xen_tmem_destroy_pool(u32 pool_id)
 160 {
 161         struct tmem_oid oid = { { 0 } };
 162
 163         return xen_tmem_op(TMEM_DESTROY_POOL, pool_id, oid, 0, 0, 0, 0, 0);
 164 }
 165
 166 /* cleancache ops */
 167
 168 static void tmem_cleancache_put_page(int pool, struct cleancache_filekey key,
 169                                      pgoff_t index, struct page *page)
 170 {
 171         u32 ind = (u32) index;
 172         struct tmem_oid oid = *(struct tmem_oid *)&key;
 173
 174         if (pool < 0)
 175                 return;
 176         if (ind != index)
 177                 return;
 178         mb(); /* ensure page is quiescent; tmem may address it with an alias */
 179         (void)xen_tmem_put_page((u32)pool, oid, ind, page);
 180 }
 181
 182 static int tmem_cleancache_get_page(int pool, struct cleancache_filekey key,
 183                                     pgoff_t index, struct page *page)
 184 {
 185         u32 ind = (u32) index;
 186         struct tmem_oid oid = *(struct tmem_oid *)&key;
 187         int ret;
 188
 189         /* translate return values to linux semantics */
 190         if (pool < 0)
 191                 return -1;
 192         if (ind != index)
 193                 return -1;
 194         ret = xen_tmem_get_page((u32)pool, oid, ind, page);
 195         if (ret == 1)
 196                 return 0;
 197         else
 198                 return -1;
 199 }
 200
 201 static void tmem_cleancache_flush_page(int pool, struct cleancache_filekey key,
 202                                        pgoff_t index)
 203 {
 204         u32 ind = (u32) index;
 205         struct tmem_oid oid = *(struct tmem_oid *)&key;
 206
 207         if (pool < 0)
 208                 return;
 209         if (ind != index)
 210                 return;
 211         (void)xen_tmem_flush_page((u32)pool, oid, ind);
 212 }
 213
 214 static void tmem_cleancache_flush_inode(int pool, struct cleancache_filekey key)
 215 {
 216         struct tmem_oid oid = *(struct tmem_oid *)&key;
 217
 218         if (pool < 0)
 219                 return;
 220         (void)xen_tmem_flush_object((u32)pool, oid);
 221 }
 222
 223 static void tmem_cleancache_flush_fs(int pool)
 224 {
 225         if (pool < 0)
 226                 return;
 227         (void)xen_tmem_destroy_pool((u32)pool);
 228 }
 229
 230 static int tmem_cleancache_init_fs(size_t pagesize)
 231 {
 232         struct tmem_pool_uuid uuid_private = TMEM_POOL_PRIVATE_UUID;
 233
 234         return xen_tmem_new_pool(uuid_private, 0, pagesize);
 235 }
 236
 237 static int tmem_cleancache_init_shared_fs(uuid_t *uuid, size_t pagesize)
 238 {
 239         struct tmem_pool_uuid shared_uuid;
 240
 241         shared_uuid.uuid_lo = *(u64 *)&uuid->b[0];
 242         shared_uuid.uuid_hi = *(u64 *)&uuid->b[8];
 243         return xen_tmem_new_pool(shared_uuid, TMEM_POOL_SHARED, pagesize);
 244 }
 245
 246 static const struct cleancache_ops tmem_cleancache_ops = {
 247         .put_page = tmem_cleancache_put_page,
 248         .get_page = tmem_cleancache_get_page,
 249         .invalidate_page = tmem_cleancache_flush_page,
 250         .invalidate_inode = tmem_cleancache_flush_inode,
 251         .invalidate_fs = tmem_cleancache_flush_fs,
 252         .init_shared_fs = tmem_cleancache_init_shared_fs,
 253         .init_fs = tmem_cleancache_init_fs
 254 };
 255 #endif
 256
 257 #ifdef CONFIG_FRONTSWAP
 258 /* frontswap tmem operations */
 259
 260 /* a single tmem poolid is used for all frontswap "types" (swapfiles) */
 261 static int tmem_frontswap_poolid;
 262
 263 /*
 264  * Swizzling increases objects per swaptype, increasing tmem concurrency
 265  * for heavy swaploads.  Later, larger nr_cpus -> larger SWIZ_BITS
 266  */
 267 #define SWIZ_BITS               4
 268 #define SWIZ_MASK               ((1 << SWIZ_BITS) - 1)
 269 #define _oswiz(_type, _ind)     ((_type << SWIZ_BITS) | (_ind & SWIZ_MASK))
 270 #define iswiz(_ind)             (_ind >> SWIZ_BITS)
 271
 272 static inline struct tmem_oid oswiz(unsigned type, u32 ind)
 273 {
 274         struct tmem_oid oid = { .oid = { 0 } };
 275         oid.oid[0] = _oswiz(type, ind);
 276         return oid;
 277 }
 278
 279 /* returns 0 if the page was successfully put into frontswap, -1 if not */
 280 static int tmem_frontswap_store(unsigned type, pgoff_t offset,
 281                                    struct page *page)
 282 {
 283         u64 ind64 = (u64)offset;
 284         u32 ind = (u32)offset;
 285         int pool = tmem_frontswap_poolid;
 286         int ret;
 287
 288         /* THP isn't supported */
 289         if (PageTransHuge(page))
 290                 return -1;
 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), page);
 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         int pool = tmem_frontswap_poolid;
 315         int ret;
 316
 317         if (pool < 0)
 318                 return -1;
 319         if (ind64 != ind)
 320                 return -1;
 321         ret = xen_tmem_get_page(pool, oswiz(type, ind), iswiz(ind), page);
 322         /* translate Xen tmem return values to linux semantics */
 323         if (ret == 1)
 324                 return 0;
 325         else
 326                 return -1;
 327 }
 328
 329 /* flush a single page from frontswap */
 330 static void tmem_frontswap_flush_page(unsigned type, pgoff_t offset)
 331 {
 332         u64 ind64 = (u64)offset;
 333         u32 ind = (u32)offset;
 334         int pool = tmem_frontswap_poolid;
 335
 336         if (pool < 0)
 337                 return;
 338         if (ind64 != ind)
 339                 return;
 340         (void) xen_tmem_flush_page(pool, oswiz(type, ind), iswiz(ind));
 341 }
 342
 343 /* flush all pages from the passed swaptype */
 344 static void tmem_frontswap_flush_area(unsigned type)
 345 {
 346         int pool = tmem_frontswap_poolid;
 347         int ind;
 348
 349         if (pool < 0)
 350                 return;
 351         for (ind = SWIZ_MASK; ind >= 0; ind--)
 352                 (void)xen_tmem_flush_object(pool, oswiz(type, ind));
 353 }
 354
 355 static void tmem_frontswap_init(unsigned ignored)
 356 {
 357         struct tmem_pool_uuid private = TMEM_POOL_PRIVATE_UUID;
 358
 359         /* a single tmem poolid is used for all frontswap "types" (swapfiles) */
 360         if (tmem_frontswap_poolid < 0)
 361                 tmem_frontswap_poolid =
 362                     xen_tmem_new_pool(private, TMEM_POOL_PERSIST, PAGE_SIZE);
 363 }
 364
 365 static struct frontswap_ops 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 && frontswap) {
 380                 char *s = "";
 381
 382                 tmem_frontswap_poolid = -1;
 383                 frontswap_register_ops(&tmem_frontswap_ops);
 384                 pr_info("frontswap enabled, RAM provided by Xen Transcendent Memory%s\n",
 385                         s);
 386         }
 387 #endif
 388 #ifdef CONFIG_CLEANCACHE
 389         BUILD_BUG_ON(sizeof(struct cleancache_filekey) != sizeof(struct tmem_oid));
 390         if (tmem_enabled && cleancache) {
 391                 int err;
 392
 393                 err = cleancache_register_ops(&tmem_cleancache_ops);
 394                 if (err)
 395                         pr_warn("xen-tmem: failed to enable cleancache: %d\n",
 396                                 err);
 397                 else
 398                         pr_info("cleancache enabled, RAM provided by "
 399                                 "Xen Transcendent Memory\n");
 400         }
 401 #endif
 402 #ifdef CONFIG_XEN_SELFBALLOONING
 403         /*
 404          * There is no point of driving pages to the swap system if they
 405          * aren't going anywhere in tmem universe.
 406          */
 407         if (!frontswap) {
 408                 selfshrinking = false;
 409                 selfballooning = false;
 410         }
 411         xen_selfballoon_init(selfballooning, selfshrinking);
 412 #endif
 413         return 0;
 414 }
 415
 416 module_init(xen_tmem_init)
 417 MODULE_LICENSE("GPL");
 418 MODULE_AUTHOR("Dan Magenheimer <dan.magenheimer@oracle.com>");
 419 MODULE_DESCRIPTION("Shim to Xen transcendent memory");