hw/xen/xen-mapcache.c

   1 /*
   2  * Copyright (C) 2011       Citrix Ltd.
   3  *
   4  * This work is licensed under the terms of the GNU GPL, version 2.  See
   5  * the COPYING file in the top-level directory.
   6  *
   7  * Contributions after 2012-01-13 are licensed under the terms of the
   8  * GNU GPL, version 2 or (at your option) any later version.
   9  */
  10
  11 #include "qemu/osdep.h"
  12 #include "qemu/units.h"
  13 #include "qemu/error-report.h"
  14
  15 #include <sys/resource.h>
  16
  17 #include "hw/xen/xen_native.h"
  18 #include "qemu/bitmap.h"
  19
  20 #include "sysemu/runstate.h"
  21 #include "sysemu/xen-mapcache.h"
  22 #include "trace.h"
  23
  24
  25 //#define MAPCACHE_DEBUG
  26
  27 #ifdef MAPCACHE_DEBUG
  28 #  define DPRINTF(fmt, ...) do { \
  29     fprintf(stderr, "xen_mapcache: " fmt, ## __VA_ARGS__); \
  30 } while (0)
  31 #else
  32 #  define DPRINTF(fmt, ...) do { } while (0)
  33 #endif
  34
  35 #if HOST_LONG_BITS == 32
  36 #  define MCACHE_BUCKET_SHIFT 16
  37 #  define MCACHE_MAX_SIZE     (1UL<<31) /* 2GB Cap */
  38 #else
  39 #  define MCACHE_BUCKET_SHIFT 20
  40 #  define MCACHE_MAX_SIZE     (1UL<<35) /* 32GB Cap */
  41 #endif
  42 #define MCACHE_BUCKET_SIZE (1UL << MCACHE_BUCKET_SHIFT)
  43
  44 /* This is the size of the virtual address space reserve to QEMU that will not
  45  * be use by MapCache.
  46  * From empirical tests I observed that qemu use 75MB more than the
  47  * max_mcache_size.
  48  */
  49 #define NON_MCACHE_MEMORY_SIZE (80 * MiB)
  50
  51 typedef struct MapCacheEntry {
  52     hwaddr paddr_index;
  53     uint8_t *vaddr_base;
  54     unsigned long *valid_mapping;
  55     uint32_t lock;
  56 #define XEN_MAPCACHE_ENTRY_DUMMY (1 << 0)
  57     uint8_t flags;
  58     hwaddr size;
  59     struct MapCacheEntry *next;
  60 } MapCacheEntry;
  61
  62 typedef struct MapCacheRev {
  63     uint8_t *vaddr_req;
  64     hwaddr paddr_index;
  65     hwaddr size;
  66     QTAILQ_ENTRY(MapCacheRev) next;
  67     bool dma;
  68 } MapCacheRev;
  69
  70 typedef struct MapCache {
  71     MapCacheEntry *entry;
  72     unsigned long nr_buckets;
  73     QTAILQ_HEAD(, MapCacheRev) locked_entries;
  74
  75     /* For most cases (>99.9%), the page address is the same. */
  76     MapCacheEntry *last_entry;
  77     unsigned long max_mcache_size;
  78     unsigned int mcache_bucket_shift;
  79
  80     phys_offset_to_gaddr_t phys_offset_to_gaddr;
  81     QemuMutex lock;
  82     void *opaque;
  83 } MapCache;
  84
  85 static MapCache *mapcache;
  86
  87 static inline void mapcache_lock(void)
  88 {
  89     qemu_mutex_lock(&mapcache->lock);
  90 }
  91
  92 static inline void mapcache_unlock(void)
  93 {
  94     qemu_mutex_unlock(&mapcache->lock);
  95 }
  96
  97 static inline int test_bits(int nr, int size, const unsigned long *addr)
  98 {
  99     unsigned long res = find_next_zero_bit(addr, size + nr, nr);
 100     if (res >= nr + size)
 101         return 1;
 102     else
 103         return 0;
 104 }
 105
 106 void xen_map_cache_init(phys_offset_to_gaddr_t f, void *opaque)
 107 {
 108     unsigned long size;
 109     struct rlimit rlimit_as;
 110
 111     mapcache = g_new0(MapCache, 1);
 112
 113     mapcache->phys_offset_to_gaddr = f;
 114     mapcache->opaque = opaque;
 115     qemu_mutex_init(&mapcache->lock);
 116
 117     QTAILQ_INIT(&mapcache->locked_entries);
 118
 119     if (geteuid() == 0) {
 120         rlimit_as.rlim_cur = RLIM_INFINITY;
 121         rlimit_as.rlim_max = RLIM_INFINITY;
 122         mapcache->max_mcache_size = MCACHE_MAX_SIZE;
 123     } else {
 124         getrlimit(RLIMIT_AS, &rlimit_as);
 125         rlimit_as.rlim_cur = rlimit_as.rlim_max;
 126
 127         if (rlimit_as.rlim_max != RLIM_INFINITY) {
 128             warn_report("QEMU's maximum size of virtual"
 129                         " memory is not infinity");
 130         }
 131         if (rlimit_as.rlim_max < MCACHE_MAX_SIZE + NON_MCACHE_MEMORY_SIZE) {
 132             mapcache->max_mcache_size = rlimit_as.rlim_max -
 133                 NON_MCACHE_MEMORY_SIZE;
 134         } else {
 135             mapcache->max_mcache_size = MCACHE_MAX_SIZE;
 136         }
 137     }
 138
 139     setrlimit(RLIMIT_AS, &rlimit_as);
 140
 141     mapcache->nr_buckets =
 142         (((mapcache->max_mcache_size >> XC_PAGE_SHIFT) +
 143           (1UL << (MCACHE_BUCKET_SHIFT - XC_PAGE_SHIFT)) - 1) >>
 144          (MCACHE_BUCKET_SHIFT - XC_PAGE_SHIFT));
 145
 146     size = mapcache->nr_buckets * sizeof (MapCacheEntry);
 147     size = (size + XC_PAGE_SIZE - 1) & ~(XC_PAGE_SIZE - 1);
 148     DPRINTF("%s, nr_buckets = %lx size %lu\n", __func__,
 149             mapcache->nr_buckets, size);
 150     mapcache->entry = g_malloc0(size);
 151 }
 152
 153 static void xen_remap_bucket(MapCacheEntry *entry,
 154                              void *vaddr,
 155                              hwaddr size,
 156                              hwaddr address_index,
 157                              bool dummy)
 158 {
 159     uint8_t *vaddr_base;
 160     xen_pfn_t *pfns;
 161     int *err;
 162     unsigned int i;
 163     hwaddr nb_pfn = size >> XC_PAGE_SHIFT;
 164
 165     trace_xen_remap_bucket(address_index);
 166
 167     pfns = g_new0(xen_pfn_t, nb_pfn);
 168     err = g_new0(int, nb_pfn);
 169
 170     if (entry->vaddr_base != NULL) {
 171         if (!(entry->flags & XEN_MAPCACHE_ENTRY_DUMMY)) {
 172             ram_block_notify_remove(entry->vaddr_base, entry->size,
 173                                     entry->size);
 174         }
 175
 176         /*
 177          * If an entry is being replaced by another mapping and we're using
 178          * MAP_FIXED flag for it - there is possibility of a race for vaddr
 179          * address with another thread doing an mmap call itself
 180          * (see man 2 mmap). To avoid that we skip explicit unmapping here
 181          * and allow the kernel to destroy the previous mappings by replacing
 182          * them in mmap call later.
 183          *
 184          * Non-identical replacements are not allowed therefore.
 185          */
 186         assert(!vaddr || (entry->vaddr_base == vaddr && entry->size == size));
 187
 188         if (!vaddr && munmap(entry->vaddr_base, entry->size) != 0) {
 189             perror("unmap fails");
 190             exit(-1);
 191         }
 192     }
 193     g_free(entry->valid_mapping);
 194     entry->valid_mapping = NULL;
 195
 196     for (i = 0; i < nb_pfn; i++) {
 197         pfns[i] = (address_index << (MCACHE_BUCKET_SHIFT-XC_PAGE_SHIFT)) + i;
 198     }
 199
 200     /*
 201      * If the caller has requested the mapping at a specific address use
 202      * MAP_FIXED to make sure it's honored.
 203      */
 204     if (!dummy) {
 205         vaddr_base = xenforeignmemory_map2(xen_fmem, xen_domid, vaddr,
 206                                            PROT_READ | PROT_WRITE,
 207                                            vaddr ? MAP_FIXED : 0,
 208                                            nb_pfn, pfns, err);
 209         if (vaddr_base == NULL) {
 210             perror("xenforeignmemory_map2");
 211             exit(-1);
 212         }
 213     } else {
 214         /*
 215          * We create dummy mappings where we are unable to create a foreign
 216          * mapping immediately due to certain circumstances (i.e. on resume now)
 217          */
 218         vaddr_base = mmap(vaddr, size, PROT_READ | PROT_WRITE,
 219                           MAP_ANON | MAP_SHARED | (vaddr ? MAP_FIXED : 0),
 220                           -1, 0);
 221         if (vaddr_base == MAP_FAILED) {
 222             perror("mmap");
 223             exit(-1);
 224         }
 225     }
 226
 227     if (!(entry->flags & XEN_MAPCACHE_ENTRY_DUMMY)) {
 228         ram_block_notify_add(vaddr_base, size, size);
 229     }
 230
 231     entry->vaddr_base = vaddr_base;
 232     entry->paddr_index = address_index;
 233     entry->size = size;
 234     entry->valid_mapping = g_new0(unsigned long,
 235                                   BITS_TO_LONGS(size >> XC_PAGE_SHIFT));
 236
 237     if (dummy) {
 238         entry->flags |= XEN_MAPCACHE_ENTRY_DUMMY;
 239     } else {
 240         entry->flags &= ~(XEN_MAPCACHE_ENTRY_DUMMY);
 241     }
 242
 243     bitmap_zero(entry->valid_mapping, nb_pfn);
 244     for (i = 0; i < nb_pfn; i++) {
 245         if (!err[i]) {
 246             bitmap_set(entry->valid_mapping, i, 1);
 247         }
 248     }
 249
 250     g_free(pfns);
 251     g_free(err);
 252 }
 253
 254 static uint8_t *xen_map_cache_unlocked(hwaddr phys_addr, hwaddr size,
 255                                        uint8_t lock, bool dma)
 256 {
 257     MapCacheEntry *entry, *pentry = NULL,
 258                   *free_entry = NULL, *free_pentry = NULL;
 259     hwaddr address_index;
 260     hwaddr address_offset;
 261     hwaddr cache_size = size;
 262     hwaddr test_bit_size;
 263     bool translated G_GNUC_UNUSED = false;
 264     bool dummy = false;
 265
 266 tryagain:
 267     address_index  = phys_addr >> MCACHE_BUCKET_SHIFT;
 268     address_offset = phys_addr & (MCACHE_BUCKET_SIZE - 1);
 269
 270     trace_xen_map_cache(phys_addr);
 271
 272     /* test_bit_size is always a multiple of XC_PAGE_SIZE */
 273     if (size) {
 274         test_bit_size = size + (phys_addr & (XC_PAGE_SIZE - 1));
 275
 276         if (test_bit_size % XC_PAGE_SIZE) {
 277             test_bit_size += XC_PAGE_SIZE - (test_bit_size % XC_PAGE_SIZE);
 278         }
 279     } else {
 280         test_bit_size = XC_PAGE_SIZE;
 281     }
 282
 283     if (mapcache->last_entry != NULL &&
 284         mapcache->last_entry->paddr_index == address_index &&
 285         !lock && !size &&
 286         test_bits(address_offset >> XC_PAGE_SHIFT,
 287                   test_bit_size >> XC_PAGE_SHIFT,
 288                   mapcache->last_entry->valid_mapping)) {
 289         trace_xen_map_cache_return(mapcache->last_entry->vaddr_base + address_offset);
 290         return mapcache->last_entry->vaddr_base + address_offset;
 291     }
 292
 293     /* size is always a multiple of MCACHE_BUCKET_SIZE */
 294     if (size) {
 295         cache_size = size + address_offset;
 296         if (cache_size % MCACHE_BUCKET_SIZE) {
 297             cache_size += MCACHE_BUCKET_SIZE - (cache_size % MCACHE_BUCKET_SIZE);
 298         }
 299     } else {
 300         cache_size = MCACHE_BUCKET_SIZE;
 301     }
 302
 303     entry = &mapcache->entry[address_index % mapcache->nr_buckets];
 304
 305     while (entry && (lock || entry->lock) && entry->vaddr_base &&
 306             (entry->paddr_index != address_index || entry->size != cache_size ||
 307              !test_bits(address_offset >> XC_PAGE_SHIFT,
 308                  test_bit_size >> XC_PAGE_SHIFT,
 309                  entry->valid_mapping))) {
 310         if (!free_entry && !entry->lock) {
 311             free_entry = entry;
 312             free_pentry = pentry;
 313         }
 314         pentry = entry;
 315         entry = entry->next;
 316     }
 317     if (!entry && free_entry) {
 318         entry = free_entry;
 319         pentry = free_pentry;
 320     }
 321     if (!entry) {
 322         entry = g_new0(MapCacheEntry, 1);
 323         pentry->next = entry;
 324         xen_remap_bucket(entry, NULL, cache_size, address_index, dummy);
 325     } else if (!entry->lock) {
 326         if (!entry->vaddr_base || entry->paddr_index != address_index ||
 327                 entry->size != cache_size ||
 328                 !test_bits(address_offset >> XC_PAGE_SHIFT,
 329                     test_bit_size >> XC_PAGE_SHIFT,
 330                     entry->valid_mapping)) {
 331             xen_remap_bucket(entry, NULL, cache_size, address_index, dummy);
 332         }
 333     }
 334
 335     if(!test_bits(address_offset >> XC_PAGE_SHIFT,
 336                 test_bit_size >> XC_PAGE_SHIFT,
 337                 entry->valid_mapping)) {
 338         mapcache->last_entry = NULL;
 339 #ifdef XEN_COMPAT_PHYSMAP
 340         if (!translated && mapcache->phys_offset_to_gaddr) {
 341             phys_addr = mapcache->phys_offset_to_gaddr(phys_addr, size);
 342             translated = true;
 343             goto tryagain;
 344         }
 345 #endif
 346         if (!dummy && runstate_check(RUN_STATE_INMIGRATE)) {
 347             dummy = true;
 348             goto tryagain;
 349         }
 350         trace_xen_map_cache_return(NULL);
 351         return NULL;
 352     }
 353
 354     mapcache->last_entry = entry;
 355     if (lock) {
 356         MapCacheRev *reventry = g_new0(MapCacheRev, 1);
 357         entry->lock++;
 358         if (entry->lock == 0) {
 359             fprintf(stderr,
 360                     "mapcache entry lock overflow: "HWADDR_FMT_plx" -> %p\n",
 361                     entry->paddr_index, entry->vaddr_base);
 362             abort();
 363         }
 364         reventry->dma = dma;
 365         reventry->vaddr_req = mapcache->last_entry->vaddr_base + address_offset;
 366         reventry->paddr_index = mapcache->last_entry->paddr_index;
 367         reventry->size = entry->size;
 368         QTAILQ_INSERT_HEAD(&mapcache->locked_entries, reventry, next);
 369     }
 370
 371     trace_xen_map_cache_return(mapcache->last_entry->vaddr_base + address_offset);
 372     return mapcache->last_entry->vaddr_base + address_offset;
 373 }
 374
 375 uint8_t *xen_map_cache(hwaddr phys_addr, hwaddr size,
 376                        uint8_t lock, bool dma)
 377 {
 378     uint8_t *p;
 379
 380     mapcache_lock();
 381     p = xen_map_cache_unlocked(phys_addr, size, lock, dma);
 382     mapcache_unlock();
 383     return p;
 384 }
 385
 386 ram_addr_t xen_ram_addr_from_mapcache(void *ptr)
 387 {
 388     MapCacheEntry *entry = NULL;
 389     MapCacheRev *reventry;
 390     hwaddr paddr_index;
 391     hwaddr size;
 392     ram_addr_t raddr;
 393     int found = 0;
 394
 395     mapcache_lock();
 396     QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 397         if (reventry->vaddr_req == ptr) {
 398             paddr_index = reventry->paddr_index;
 399             size = reventry->size;
 400             found = 1;
 401             break;
 402         }
 403     }
 404     if (!found) {
 405         fprintf(stderr, "%s, could not find %p\n", __func__, ptr);
 406         QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 407             DPRINTF("   "HWADDR_FMT_plx" -> %p is present\n", reventry->paddr_index,
 408                     reventry->vaddr_req);
 409         }
 410         abort();
 411         return 0;
 412     }
 413
 414     entry = &mapcache->entry[paddr_index % mapcache->nr_buckets];
 415     while (entry && (entry->paddr_index != paddr_index || entry->size != size)) {
 416         entry = entry->next;
 417     }
 418     if (!entry) {
 419         DPRINTF("Trying to find address %p that is not in the mapcache!\n", ptr);
 420         raddr = 0;
 421     } else {
 422         raddr = (reventry->paddr_index << MCACHE_BUCKET_SHIFT) +
 423              ((unsigned long) ptr - (unsigned long) entry->vaddr_base);
 424     }
 425     mapcache_unlock();
 426     return raddr;
 427 }
 428
 429 static void xen_invalidate_map_cache_entry_unlocked(uint8_t *buffer)
 430 {
 431     MapCacheEntry *entry = NULL, *pentry = NULL;
 432     MapCacheRev *reventry;
 433     hwaddr paddr_index;
 434     hwaddr size;
 435     int found = 0;
 436
 437     QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 438         if (reventry->vaddr_req == buffer) {
 439             paddr_index = reventry->paddr_index;
 440             size = reventry->size;
 441             found = 1;
 442             break;
 443         }
 444     }
 445     if (!found) {
 446         DPRINTF("%s, could not find %p\n", __func__, buffer);
 447         QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 448             DPRINTF("   "HWADDR_FMT_plx" -> %p is present\n", reventry->paddr_index, reventry->vaddr_req);
 449         }
 450         return;
 451     }
 452     QTAILQ_REMOVE(&mapcache->locked_entries, reventry, next);
 453     g_free(reventry);
 454
 455     if (mapcache->last_entry != NULL &&
 456         mapcache->last_entry->paddr_index == paddr_index) {
 457         mapcache->last_entry = NULL;
 458     }
 459
 460     entry = &mapcache->entry[paddr_index % mapcache->nr_buckets];
 461     while (entry && (entry->paddr_index != paddr_index || entry->size != size)) {
 462         pentry = entry;
 463         entry = entry->next;
 464     }
 465     if (!entry) {
 466         DPRINTF("Trying to unmap address %p that is not in the mapcache!\n", buffer);
 467         return;
 468     }
 469     entry->lock--;
 470     if (entry->lock > 0 || pentry == NULL) {
 471         return;
 472     }
 473
 474     pentry->next = entry->next;
 475     ram_block_notify_remove(entry->vaddr_base, entry->size, entry->size);
 476     if (munmap(entry->vaddr_base, entry->size) != 0) {
 477         perror("unmap fails");
 478         exit(-1);
 479     }
 480     g_free(entry->valid_mapping);
 481     g_free(entry);
 482 }
 483
 484 void xen_invalidate_map_cache_entry(uint8_t *buffer)
 485 {
 486     mapcache_lock();
 487     xen_invalidate_map_cache_entry_unlocked(buffer);
 488     mapcache_unlock();
 489 }
 490
 491 void xen_invalidate_map_cache(void)
 492 {
 493     unsigned long i;
 494     MapCacheRev *reventry;
 495
 496     /* Flush pending AIO before destroying the mapcache */
 497     bdrv_drain_all();
 498
 499     mapcache_lock();
 500
 501     QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 502         if (!reventry->dma) {
 503             continue;
 504         }
 505         fprintf(stderr, "Locked DMA mapping while invalidating mapcache!"
 506                 " "HWADDR_FMT_plx" -> %p is present\n",
 507                 reventry->paddr_index, reventry->vaddr_req);
 508     }
 509
 510     for (i = 0; i < mapcache->nr_buckets; i++) {
 511         MapCacheEntry *entry = &mapcache->entry[i];
 512
 513         if (entry->vaddr_base == NULL) {
 514             continue;
 515         }
 516         if (entry->lock > 0) {
 517             continue;
 518         }
 519
 520         if (munmap(entry->vaddr_base, entry->size) != 0) {
 521             perror("unmap fails");
 522             exit(-1);
 523         }
 524
 525         entry->paddr_index = 0;
 526         entry->vaddr_base = NULL;
 527         entry->size = 0;
 528         g_free(entry->valid_mapping);
 529         entry->valid_mapping = NULL;
 530     }
 531
 532     mapcache->last_entry = NULL;
 533
 534     mapcache_unlock();
 535 }
 536
 537 static uint8_t *xen_replace_cache_entry_unlocked(hwaddr old_phys_addr,
 538                                                  hwaddr new_phys_addr,
 539                                                  hwaddr size)
 540 {
 541     MapCacheEntry *entry;
 542     hwaddr address_index, address_offset;
 543     hwaddr test_bit_size, cache_size = size;
 544
 545     address_index  = old_phys_addr >> MCACHE_BUCKET_SHIFT;
 546     address_offset = old_phys_addr & (MCACHE_BUCKET_SIZE - 1);
 547
 548     assert(size);
 549     /* test_bit_size is always a multiple of XC_PAGE_SIZE */
 550     test_bit_size = size + (old_phys_addr & (XC_PAGE_SIZE - 1));
 551     if (test_bit_size % XC_PAGE_SIZE) {
 552         test_bit_size += XC_PAGE_SIZE - (test_bit_size % XC_PAGE_SIZE);
 553     }
 554     cache_size = size + address_offset;
 555     if (cache_size % MCACHE_BUCKET_SIZE) {
 556         cache_size += MCACHE_BUCKET_SIZE - (cache_size % MCACHE_BUCKET_SIZE);
 557     }
 558
 559     entry = &mapcache->entry[address_index % mapcache->nr_buckets];
 560     while (entry && !(entry->paddr_index == address_index &&
 561                       entry->size == cache_size)) {
 562         entry = entry->next;
 563     }
 564     if (!entry) {
 565         DPRINTF("Trying to update an entry for "HWADDR_FMT_plx \
 566                 "that is not in the mapcache!\n", old_phys_addr);
 567         return NULL;
 568     }
 569
 570     address_index  = new_phys_addr >> MCACHE_BUCKET_SHIFT;
 571     address_offset = new_phys_addr & (MCACHE_BUCKET_SIZE - 1);
 572
 573     fprintf(stderr, "Replacing a dummy mapcache entry for "HWADDR_FMT_plx \
 574             " with "HWADDR_FMT_plx"\n", old_phys_addr, new_phys_addr);
 575
 576     xen_remap_bucket(entry, entry->vaddr_base,
 577                      cache_size, address_index, false);
 578     if (!test_bits(address_offset >> XC_PAGE_SHIFT,
 579                 test_bit_size >> XC_PAGE_SHIFT,
 580                 entry->valid_mapping)) {
 581         DPRINTF("Unable to update a mapcache entry for "HWADDR_FMT_plx"!\n",
 582                 old_phys_addr);
 583         return NULL;
 584     }
 585
 586     return entry->vaddr_base + address_offset;
 587 }
 588
 589 uint8_t *xen_replace_cache_entry(hwaddr old_phys_addr,
 590                                  hwaddr new_phys_addr,
 591                                  hwaddr size)
 592 {
 593     uint8_t *p;
 594
 595     mapcache_lock();
 596     p = xen_replace_cache_entry_unlocked(old_phys_addr, new_phys_addr, size);
 597     mapcache_unlock();
 598     return p;
 599 }