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 "config.h"
  12
  13 #include <sys/resource.h>
  14
  15 #include "hw/xen/xen_backend.h"
  16 #include "sysemu/blockdev.h"
  17 #include "qemu/bitmap.h"
  18
  19 #include <xen/hvm/params.h>
  20 #include <sys/mman.h>
  21
  22 #include "sysemu/xen-mapcache.h"
  23 #include "trace.h"
  24
  25
  26 //#define MAPCACHE_DEBUG
  27
  28 #ifdef MAPCACHE_DEBUG
  29 #  define DPRINTF(fmt, ...) do { \
  30     fprintf(stderr, "xen_mapcache: " fmt, ## __VA_ARGS__); \
  31 } while (0)
  32 #else
  33 #  define DPRINTF(fmt, ...) do { } while (0)
  34 #endif
  35
  36 #if HOST_LONG_BITS == 32
  37 #  define MCACHE_BUCKET_SHIFT 16
  38 #  define MCACHE_MAX_SIZE     (1UL<<31) /* 2GB Cap */
  39 #else
  40 #  define MCACHE_BUCKET_SHIFT 20
  41 #  define MCACHE_MAX_SIZE     (1UL<<35) /* 32GB Cap */
  42 #endif
  43 #define MCACHE_BUCKET_SIZE (1UL << MCACHE_BUCKET_SHIFT)
  44
  45 /* This is the size of the virtual address space reserve to QEMU that will not
  46  * be use by MapCache.
  47  * From empirical tests I observed that qemu use 75MB more than the
  48  * max_mcache_size.
  49  */
  50 #define NON_MCACHE_MEMORY_SIZE (80 * 1024 * 1024)
  51
  52 #define mapcache_lock()   ((void)0)
  53 #define mapcache_unlock() ((void)0)
  54
  55 typedef struct MapCacheEntry {
  56     hwaddr paddr_index;
  57     uint8_t *vaddr_base;
  58     unsigned long *valid_mapping;
  59     uint8_t lock;
  60     hwaddr size;
  61     struct MapCacheEntry *next;
  62 } MapCacheEntry;
  63
  64 typedef struct MapCacheRev {
  65     uint8_t *vaddr_req;
  66     hwaddr paddr_index;
  67     hwaddr size;
  68     QTAILQ_ENTRY(MapCacheRev) next;
  69 } MapCacheRev;
  70
  71 typedef struct MapCache {
  72     MapCacheEntry *entry;
  73     unsigned long nr_buckets;
  74     QTAILQ_HEAD(map_cache_head, MapCacheRev) locked_entries;
  75
  76     /* For most cases (>99.9%), the page address is the same. */
  77     MapCacheEntry *last_entry;
  78     unsigned long max_mcache_size;
  79     unsigned int mcache_bucket_shift;
  80
  81     phys_offset_to_gaddr_t phys_offset_to_gaddr;
  82     void *opaque;
  83 } MapCache;
  84
  85 static MapCache *mapcache;
  86
  87 static inline int test_bits(int nr, int size, const unsigned long *addr)
  88 {
  89     unsigned long res = find_next_zero_bit(addr, size + nr, nr);
  90     if (res >= nr + size)
  91         return 1;
  92     else
  93         return 0;
  94 }
  95
  96 void xen_map_cache_init(phys_offset_to_gaddr_t f, void *opaque)
  97 {
  98     unsigned long size;
  99     struct rlimit rlimit_as;
 100
 101     mapcache = g_malloc0(sizeof (MapCache));
 102
 103     mapcache->phys_offset_to_gaddr = f;
 104     mapcache->opaque = opaque;
 105
 106     QTAILQ_INIT(&mapcache->locked_entries);
 107
 108     if (geteuid() == 0) {
 109         rlimit_as.rlim_cur = RLIM_INFINITY;
 110         rlimit_as.rlim_max = RLIM_INFINITY;
 111         mapcache->max_mcache_size = MCACHE_MAX_SIZE;
 112     } else {
 113         getrlimit(RLIMIT_AS, &rlimit_as);
 114         rlimit_as.rlim_cur = rlimit_as.rlim_max;
 115
 116         if (rlimit_as.rlim_max != RLIM_INFINITY) {
 117             fprintf(stderr, "Warning: QEMU's maximum size of virtual"
 118                     " memory is not infinity.\n");
 119         }
 120         if (rlimit_as.rlim_max < MCACHE_MAX_SIZE + NON_MCACHE_MEMORY_SIZE) {
 121             mapcache->max_mcache_size = rlimit_as.rlim_max -
 122                 NON_MCACHE_MEMORY_SIZE;
 123         } else {
 124             mapcache->max_mcache_size = MCACHE_MAX_SIZE;
 125         }
 126     }
 127
 128     setrlimit(RLIMIT_AS, &rlimit_as);
 129
 130     mapcache->nr_buckets =
 131         (((mapcache->max_mcache_size >> XC_PAGE_SHIFT) +
 132           (1UL << (MCACHE_BUCKET_SHIFT - XC_PAGE_SHIFT)) - 1) >>
 133          (MCACHE_BUCKET_SHIFT - XC_PAGE_SHIFT));
 134
 135     size = mapcache->nr_buckets * sizeof (MapCacheEntry);
 136     size = (size + XC_PAGE_SIZE - 1) & ~(XC_PAGE_SIZE - 1);
 137     DPRINTF("%s, nr_buckets = %lx size %lu\n", __func__,
 138             mapcache->nr_buckets, size);
 139     mapcache->entry = g_malloc0(size);
 140 }
 141
 142 static void xen_remap_bucket(MapCacheEntry *entry,
 143                              hwaddr size,
 144                              hwaddr address_index)
 145 {
 146     uint8_t *vaddr_base;
 147     xen_pfn_t *pfns;
 148     int *err;
 149     unsigned int i;
 150     hwaddr nb_pfn = size >> XC_PAGE_SHIFT;
 151
 152     trace_xen_remap_bucket(address_index);
 153
 154     pfns = g_malloc0(nb_pfn * sizeof (xen_pfn_t));
 155     err = g_malloc0(nb_pfn * sizeof (int));
 156
 157     if (entry->vaddr_base != NULL) {
 158         if (munmap(entry->vaddr_base, entry->size) != 0) {
 159             perror("unmap fails");
 160             exit(-1);
 161         }
 162     }
 163     if (entry->valid_mapping != NULL) {
 164         g_free(entry->valid_mapping);
 165         entry->valid_mapping = NULL;
 166     }
 167
 168     for (i = 0; i < nb_pfn; i++) {
 169         pfns[i] = (address_index << (MCACHE_BUCKET_SHIFT-XC_PAGE_SHIFT)) + i;
 170     }
 171
 172     vaddr_base = xc_map_foreign_bulk(xen_xc, xen_domid, PROT_READ|PROT_WRITE,
 173                                      pfns, err, nb_pfn);
 174     if (vaddr_base == NULL) {
 175         perror("xc_map_foreign_bulk");
 176         exit(-1);
 177     }
 178
 179     entry->vaddr_base = vaddr_base;
 180     entry->paddr_index = address_index;
 181     entry->size = size;
 182     entry->valid_mapping = (unsigned long *) g_malloc0(sizeof(unsigned long) *
 183             BITS_TO_LONGS(size >> XC_PAGE_SHIFT));
 184
 185     bitmap_zero(entry->valid_mapping, nb_pfn);
 186     for (i = 0; i < nb_pfn; i++) {
 187         if (!err[i]) {
 188             bitmap_set(entry->valid_mapping, i, 1);
 189         }
 190     }
 191
 192     g_free(pfns);
 193     g_free(err);
 194 }
 195
 196 uint8_t *xen_map_cache(hwaddr phys_addr, hwaddr size,
 197                        uint8_t lock)
 198 {
 199     MapCacheEntry *entry, *pentry = NULL;
 200     hwaddr address_index;
 201     hwaddr address_offset;
 202     hwaddr __size = size;
 203     hwaddr __test_bit_size = size;
 204     bool translated = false;
 205
 206 tryagain:
 207     address_index  = phys_addr >> MCACHE_BUCKET_SHIFT;
 208     address_offset = phys_addr & (MCACHE_BUCKET_SIZE - 1);
 209
 210     trace_xen_map_cache(phys_addr);
 211
 212     /* __test_bit_size is always a multiple of XC_PAGE_SIZE */
 213     if (size) {
 214         __test_bit_size = size + (phys_addr & (XC_PAGE_SIZE - 1));
 215
 216         if (__test_bit_size % XC_PAGE_SIZE) {
 217             __test_bit_size += XC_PAGE_SIZE - (__test_bit_size % XC_PAGE_SIZE);
 218         }
 219     } else {
 220         __test_bit_size = XC_PAGE_SIZE;
 221     }
 222
 223     if (mapcache->last_entry != NULL &&
 224         mapcache->last_entry->paddr_index == address_index &&
 225         !lock && !__size &&
 226         test_bits(address_offset >> XC_PAGE_SHIFT,
 227                   __test_bit_size >> XC_PAGE_SHIFT,
 228                   mapcache->last_entry->valid_mapping)) {
 229         trace_xen_map_cache_return(mapcache->last_entry->vaddr_base + address_offset);
 230         return mapcache->last_entry->vaddr_base + address_offset;
 231     }
 232
 233     /* size is always a multiple of MCACHE_BUCKET_SIZE */
 234     if (size) {
 235         __size = size + address_offset;
 236         if (__size % MCACHE_BUCKET_SIZE) {
 237             __size += MCACHE_BUCKET_SIZE - (__size % MCACHE_BUCKET_SIZE);
 238         }
 239     } else {
 240         __size = MCACHE_BUCKET_SIZE;
 241     }
 242
 243     entry = &mapcache->entry[address_index % mapcache->nr_buckets];
 244
 245     while (entry && entry->lock && entry->vaddr_base &&
 246             (entry->paddr_index != address_index || entry->size != __size ||
 247              !test_bits(address_offset >> XC_PAGE_SHIFT,
 248                  __test_bit_size >> XC_PAGE_SHIFT,
 249                  entry->valid_mapping))) {
 250         pentry = entry;
 251         entry = entry->next;
 252     }
 253     if (!entry) {
 254         entry = g_malloc0(sizeof (MapCacheEntry));
 255         pentry->next = entry;
 256         xen_remap_bucket(entry, __size, address_index);
 257     } else if (!entry->lock) {
 258         if (!entry->vaddr_base || entry->paddr_index != address_index ||
 259                 entry->size != __size ||
 260                 !test_bits(address_offset >> XC_PAGE_SHIFT,
 261                     __test_bit_size >> XC_PAGE_SHIFT,
 262                     entry->valid_mapping)) {
 263             xen_remap_bucket(entry, __size, address_index);
 264         }
 265     }
 266
 267     if(!test_bits(address_offset >> XC_PAGE_SHIFT,
 268                 __test_bit_size >> XC_PAGE_SHIFT,
 269                 entry->valid_mapping)) {
 270         mapcache->last_entry = NULL;
 271         if (!translated && mapcache->phys_offset_to_gaddr) {
 272             phys_addr = mapcache->phys_offset_to_gaddr(phys_addr, size, mapcache->opaque);
 273             translated = true;
 274             goto tryagain;
 275         }
 276         trace_xen_map_cache_return(NULL);
 277         return NULL;
 278     }
 279
 280     mapcache->last_entry = entry;
 281     if (lock) {
 282         MapCacheRev *reventry = g_malloc0(sizeof(MapCacheRev));
 283         entry->lock++;
 284         reventry->vaddr_req = mapcache->last_entry->vaddr_base + address_offset;
 285         reventry->paddr_index = mapcache->last_entry->paddr_index;
 286         reventry->size = entry->size;
 287         QTAILQ_INSERT_HEAD(&mapcache->locked_entries, reventry, next);
 288     }
 289
 290     trace_xen_map_cache_return(mapcache->last_entry->vaddr_base + address_offset);
 291     return mapcache->last_entry->vaddr_base + address_offset;
 292 }
 293
 294 ram_addr_t xen_ram_addr_from_mapcache(void *ptr)
 295 {
 296     MapCacheEntry *entry = NULL;
 297     MapCacheRev *reventry;
 298     hwaddr paddr_index;
 299     hwaddr size;
 300     int found = 0;
 301
 302     QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 303         if (reventry->vaddr_req == ptr) {
 304             paddr_index = reventry->paddr_index;
 305             size = reventry->size;
 306             found = 1;
 307             break;
 308         }
 309     }
 310     if (!found) {
 311         fprintf(stderr, "%s, could not find %p\n", __func__, ptr);
 312         QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 313             DPRINTF("   "TARGET_FMT_plx" -> %p is present\n", reventry->paddr_index,
 314                     reventry->vaddr_req);
 315         }
 316         abort();
 317         return 0;
 318     }
 319
 320     entry = &mapcache->entry[paddr_index % mapcache->nr_buckets];
 321     while (entry && (entry->paddr_index != paddr_index || entry->size != size)) {
 322         entry = entry->next;
 323     }
 324     if (!entry) {
 325         DPRINTF("Trying to find address %p that is not in the mapcache!\n", ptr);
 326         return 0;
 327     }
 328     return (reventry->paddr_index << MCACHE_BUCKET_SHIFT) +
 329         ((unsigned long) ptr - (unsigned long) entry->vaddr_base);
 330 }
 331
 332 void xen_invalidate_map_cache_entry(uint8_t *buffer)
 333 {
 334     MapCacheEntry *entry = NULL, *pentry = NULL;
 335     MapCacheRev *reventry;
 336     hwaddr paddr_index;
 337     hwaddr size;
 338     int found = 0;
 339
 340     QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 341         if (reventry->vaddr_req == buffer) {
 342             paddr_index = reventry->paddr_index;
 343             size = reventry->size;
 344             found = 1;
 345             break;
 346         }
 347     }
 348     if (!found) {
 349         DPRINTF("%s, could not find %p\n", __func__, buffer);
 350         QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 351             DPRINTF("   "TARGET_FMT_plx" -> %p is present\n", reventry->paddr_index, reventry->vaddr_req);
 352         }
 353         return;
 354     }
 355     QTAILQ_REMOVE(&mapcache->locked_entries, reventry, next);
 356     g_free(reventry);
 357
 358     if (mapcache->last_entry != NULL &&
 359         mapcache->last_entry->paddr_index == paddr_index) {
 360         mapcache->last_entry = NULL;
 361     }
 362
 363     entry = &mapcache->entry[paddr_index % mapcache->nr_buckets];
 364     while (entry && (entry->paddr_index != paddr_index || entry->size != size)) {
 365         pentry = entry;
 366         entry = entry->next;
 367     }
 368     if (!entry) {
 369         DPRINTF("Trying to unmap address %p that is not in the mapcache!\n", buffer);
 370         return;
 371     }
 372     entry->lock--;
 373     if (entry->lock > 0 || pentry == NULL) {
 374         return;
 375     }
 376
 377     pentry->next = entry->next;
 378     if (munmap(entry->vaddr_base, entry->size) != 0) {
 379         perror("unmap fails");
 380         exit(-1);
 381     }
 382     g_free(entry->valid_mapping);
 383     g_free(entry);
 384 }
 385
 386 void xen_invalidate_map_cache(void)
 387 {
 388     unsigned long i;
 389     MapCacheRev *reventry;
 390
 391     /* Flush pending AIO before destroying the mapcache */
 392     bdrv_drain_all();
 393
 394     QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 395         DPRINTF("There should be no locked mappings at this time, "
 396                 "but "TARGET_FMT_plx" -> %p is present\n",
 397                 reventry->paddr_index, reventry->vaddr_req);
 398     }
 399
 400     mapcache_lock();
 401
 402     for (i = 0; i < mapcache->nr_buckets; i++) {
 403         MapCacheEntry *entry = &mapcache->entry[i];
 404
 405         if (entry->vaddr_base == NULL) {
 406             continue;
 407         }
 408         if (entry->lock > 0) {
 409             continue;
 410         }
 411
 412         if (munmap(entry->vaddr_base, entry->size) != 0) {
 413             perror("unmap fails");
 414             exit(-1);
 415         }
 416
 417         entry->paddr_index = 0;
 418         entry->vaddr_base = NULL;
 419         entry->size = 0;
 420         g_free(entry->valid_mapping);
 421         entry->valid_mapping = NULL;
 422     }
 423
 424     mapcache->last_entry = NULL;
 425
 426     mapcache_unlock();
 427 }