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_backend.h"
  16 #include "blockdev.h"
  17 #include "bitmap.h"
  18
  19 #include <xen/hvm/params.h>
  20 #include <sys/mman.h>
  21
  22 #include "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 defined(__i386__)
  37 #  define MCACHE_BUCKET_SHIFT 16
  38 #  define MCACHE_MAX_SIZE     (1UL<<31) /* 2GB Cap */
  39 #elif defined(__x86_64__)
  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     hwaddr last_address_index;
  78     uint8_t *last_address_vaddr;
  79     unsigned long max_mcache_size;
  80     unsigned int mcache_bucket_shift;
  81
  82     phys_offset_to_gaddr_t phys_offset_to_gaddr;
  83     void *opaque;
  84 } MapCache;
  85
  86 static MapCache *mapcache;
  87
  88 static inline int test_bits(int nr, int size, const unsigned long *addr)
  89 {
  90     unsigned long res = find_next_zero_bit(addr, size + nr, nr);
  91     if (res >= nr + size)
  92         return 1;
  93     else
  94         return 0;
  95 }
  96
  97 void xen_map_cache_init(phys_offset_to_gaddr_t f, void *opaque)
  98 {
  99     unsigned long size;
 100     struct rlimit rlimit_as;
 101
 102     mapcache = g_malloc0(sizeof (MapCache));
 103
 104     mapcache->phys_offset_to_gaddr = f;
 105     mapcache->opaque = opaque;
 106
 107     QTAILQ_INIT(&mapcache->locked_entries);
 108     mapcache->last_address_index = -1;
 109
 110     if (geteuid() == 0) {
 111         rlimit_as.rlim_cur = RLIM_INFINITY;
 112         rlimit_as.rlim_max = RLIM_INFINITY;
 113         mapcache->max_mcache_size = MCACHE_MAX_SIZE;
 114     } else {
 115         getrlimit(RLIMIT_AS, &rlimit_as);
 116         rlimit_as.rlim_cur = rlimit_as.rlim_max;
 117
 118         if (rlimit_as.rlim_max != RLIM_INFINITY) {
 119             fprintf(stderr, "Warning: QEMU's maximum size of virtual"
 120                     " memory is not infinity.\n");
 121         }
 122         if (rlimit_as.rlim_max < MCACHE_MAX_SIZE + NON_MCACHE_MEMORY_SIZE) {
 123             mapcache->max_mcache_size = rlimit_as.rlim_max -
 124                 NON_MCACHE_MEMORY_SIZE;
 125         } else {
 126             mapcache->max_mcache_size = MCACHE_MAX_SIZE;
 127         }
 128     }
 129
 130     setrlimit(RLIMIT_AS, &rlimit_as);
 131
 132     mapcache->nr_buckets =
 133         (((mapcache->max_mcache_size >> XC_PAGE_SHIFT) +
 134           (1UL << (MCACHE_BUCKET_SHIFT - XC_PAGE_SHIFT)) - 1) >>
 135          (MCACHE_BUCKET_SHIFT - XC_PAGE_SHIFT));
 136
 137     size = mapcache->nr_buckets * sizeof (MapCacheEntry);
 138     size = (size + XC_PAGE_SIZE - 1) & ~(XC_PAGE_SIZE - 1);
 139     DPRINTF("%s, nr_buckets = %lx size %lu\n", __func__,
 140             mapcache->nr_buckets, size);
 141     mapcache->entry = g_malloc0(size);
 142 }
 143
 144 static void xen_remap_bucket(MapCacheEntry *entry,
 145                              hwaddr size,
 146                              hwaddr address_index)
 147 {
 148     uint8_t *vaddr_base;
 149     xen_pfn_t *pfns;
 150     int *err;
 151     unsigned int i;
 152     hwaddr nb_pfn = size >> XC_PAGE_SHIFT;
 153
 154     trace_xen_remap_bucket(address_index);
 155
 156     pfns = g_malloc0(nb_pfn * sizeof (xen_pfn_t));
 157     err = g_malloc0(nb_pfn * sizeof (int));
 158
 159     if (entry->vaddr_base != NULL) {
 160         if (munmap(entry->vaddr_base, entry->size) != 0) {
 161             perror("unmap fails");
 162             exit(-1);
 163         }
 164     }
 165     if (entry->valid_mapping != NULL) {
 166         g_free(entry->valid_mapping);
 167         entry->valid_mapping = NULL;
 168     }
 169
 170     for (i = 0; i < nb_pfn; i++) {
 171         pfns[i] = (address_index << (MCACHE_BUCKET_SHIFT-XC_PAGE_SHIFT)) + i;
 172     }
 173
 174     vaddr_base = xc_map_foreign_bulk(xen_xc, xen_domid, PROT_READ|PROT_WRITE,
 175                                      pfns, err, nb_pfn);
 176     if (vaddr_base == NULL) {
 177         perror("xc_map_foreign_bulk");
 178         exit(-1);
 179     }
 180
 181     entry->vaddr_base = vaddr_base;
 182     entry->paddr_index = address_index;
 183     entry->size = size;
 184     entry->valid_mapping = (unsigned long *) g_malloc0(sizeof(unsigned long) *
 185             BITS_TO_LONGS(size >> XC_PAGE_SHIFT));
 186
 187     bitmap_zero(entry->valid_mapping, nb_pfn);
 188     for (i = 0; i < nb_pfn; i++) {
 189         if (!err[i]) {
 190             bitmap_set(entry->valid_mapping, i, 1);
 191         }
 192     }
 193
 194     g_free(pfns);
 195     g_free(err);
 196 }
 197
 198 uint8_t *xen_map_cache(hwaddr phys_addr, hwaddr size,
 199                        uint8_t lock)
 200 {
 201     MapCacheEntry *entry, *pentry = NULL;
 202     hwaddr address_index;
 203     hwaddr address_offset;
 204     hwaddr __size = size;
 205     bool translated = false;
 206
 207 tryagain:
 208     address_index  = phys_addr >> MCACHE_BUCKET_SHIFT;
 209     address_offset = phys_addr & (MCACHE_BUCKET_SIZE - 1);
 210
 211     trace_xen_map_cache(phys_addr);
 212
 213     if (address_index == mapcache->last_address_index && !lock && !__size) {
 214         trace_xen_map_cache_return(mapcache->last_address_vaddr + address_offset);
 215         return mapcache->last_address_vaddr + address_offset;
 216     }
 217
 218     /* size is always a multiple of MCACHE_BUCKET_SIZE */
 219     if (size) {
 220         __size = size + address_offset;
 221         if (__size % MCACHE_BUCKET_SIZE) {
 222             __size += MCACHE_BUCKET_SIZE - (__size % MCACHE_BUCKET_SIZE);
 223         }
 224     } else {
 225         __size = MCACHE_BUCKET_SIZE;
 226     }
 227
 228     entry = &mapcache->entry[address_index % mapcache->nr_buckets];
 229
 230     while (entry && entry->lock && entry->vaddr_base &&
 231             (entry->paddr_index != address_index || entry->size != __size ||
 232              !test_bits(address_offset >> XC_PAGE_SHIFT, size >> XC_PAGE_SHIFT,
 233                  entry->valid_mapping))) {
 234         pentry = entry;
 235         entry = entry->next;
 236     }
 237     if (!entry) {
 238         entry = g_malloc0(sizeof (MapCacheEntry));
 239         pentry->next = entry;
 240         xen_remap_bucket(entry, __size, address_index);
 241     } else if (!entry->lock) {
 242         if (!entry->vaddr_base || entry->paddr_index != address_index ||
 243                 entry->size != __size ||
 244                 !test_bits(address_offset >> XC_PAGE_SHIFT, size >> XC_PAGE_SHIFT,
 245                     entry->valid_mapping)) {
 246             xen_remap_bucket(entry, __size, address_index);
 247         }
 248     }
 249
 250     if(!test_bits(address_offset >> XC_PAGE_SHIFT, size >> XC_PAGE_SHIFT,
 251                 entry->valid_mapping)) {
 252         mapcache->last_address_index = -1;
 253         if (!translated && mapcache->phys_offset_to_gaddr) {
 254             phys_addr = mapcache->phys_offset_to_gaddr(phys_addr, size, mapcache->opaque);
 255             translated = true;
 256             goto tryagain;
 257         }
 258         trace_xen_map_cache_return(NULL);
 259         return NULL;
 260     }
 261
 262     mapcache->last_address_index = address_index;
 263     mapcache->last_address_vaddr = entry->vaddr_base;
 264     if (lock) {
 265         MapCacheRev *reventry = g_malloc0(sizeof(MapCacheRev));
 266         entry->lock++;
 267         reventry->vaddr_req = mapcache->last_address_vaddr + address_offset;
 268         reventry->paddr_index = mapcache->last_address_index;
 269         reventry->size = entry->size;
 270         QTAILQ_INSERT_HEAD(&mapcache->locked_entries, reventry, next);
 271     }
 272
 273     trace_xen_map_cache_return(mapcache->last_address_vaddr + address_offset);
 274     return mapcache->last_address_vaddr + address_offset;
 275 }
 276
 277 ram_addr_t xen_ram_addr_from_mapcache(void *ptr)
 278 {
 279     MapCacheEntry *entry = NULL;
 280     MapCacheRev *reventry;
 281     hwaddr paddr_index;
 282     hwaddr size;
 283     int found = 0;
 284
 285     QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 286         if (reventry->vaddr_req == ptr) {
 287             paddr_index = reventry->paddr_index;
 288             size = reventry->size;
 289             found = 1;
 290             break;
 291         }
 292     }
 293     if (!found) {
 294         fprintf(stderr, "%s, could not find %p\n", __func__, ptr);
 295         QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 296             DPRINTF("   "TARGET_FMT_plx" -> %p is present\n", reventry->paddr_index,
 297                     reventry->vaddr_req);
 298         }
 299         abort();
 300         return 0;
 301     }
 302
 303     entry = &mapcache->entry[paddr_index % mapcache->nr_buckets];
 304     while (entry && (entry->paddr_index != paddr_index || entry->size != size)) {
 305         entry = entry->next;
 306     }
 307     if (!entry) {
 308         DPRINTF("Trying to find address %p that is not in the mapcache!\n", ptr);
 309         return 0;
 310     }
 311     return (reventry->paddr_index << MCACHE_BUCKET_SHIFT) +
 312         ((unsigned long) ptr - (unsigned long) entry->vaddr_base);
 313 }
 314
 315 void xen_invalidate_map_cache_entry(uint8_t *buffer)
 316 {
 317     MapCacheEntry *entry = NULL, *pentry = NULL;
 318     MapCacheRev *reventry;
 319     hwaddr paddr_index;
 320     hwaddr size;
 321     int found = 0;
 322
 323     QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 324         if (reventry->vaddr_req == buffer) {
 325             paddr_index = reventry->paddr_index;
 326             size = reventry->size;
 327             found = 1;
 328             break;
 329         }
 330     }
 331     if (!found) {
 332         DPRINTF("%s, could not find %p\n", __func__, buffer);
 333         QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 334             DPRINTF("   "TARGET_FMT_plx" -> %p is present\n", reventry->paddr_index, reventry->vaddr_req);
 335         }
 336         return;
 337     }
 338     QTAILQ_REMOVE(&mapcache->locked_entries, reventry, next);
 339     g_free(reventry);
 340
 341     if (mapcache->last_address_index == paddr_index) {
 342         mapcache->last_address_index = -1;
 343         mapcache->last_address_vaddr = NULL;
 344     }
 345
 346     entry = &mapcache->entry[paddr_index % mapcache->nr_buckets];
 347     while (entry && (entry->paddr_index != paddr_index || entry->size != size)) {
 348         pentry = entry;
 349         entry = entry->next;
 350     }
 351     if (!entry) {
 352         DPRINTF("Trying to unmap address %p that is not in the mapcache!\n", buffer);
 353         return;
 354     }
 355     entry->lock--;
 356     if (entry->lock > 0 || pentry == NULL) {
 357         return;
 358     }
 359
 360     pentry->next = entry->next;
 361     if (munmap(entry->vaddr_base, entry->size) != 0) {
 362         perror("unmap fails");
 363         exit(-1);
 364     }
 365     g_free(entry->valid_mapping);
 366     g_free(entry);
 367 }
 368
 369 void xen_invalidate_map_cache(void)
 370 {
 371     unsigned long i;
 372     MapCacheRev *reventry;
 373
 374     /* Flush pending AIO before destroying the mapcache */
 375     bdrv_drain_all();
 376
 377     QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 378         DPRINTF("There should be no locked mappings at this time, "
 379                 "but "TARGET_FMT_plx" -> %p is present\n",
 380                 reventry->paddr_index, reventry->vaddr_req);
 381     }
 382
 383     mapcache_lock();
 384
 385     for (i = 0; i < mapcache->nr_buckets; i++) {
 386         MapCacheEntry *entry = &mapcache->entry[i];
 387
 388         if (entry->vaddr_base == NULL) {
 389             continue;
 390         }
 391         if (entry->lock > 0) {
 392             continue;
 393         }
 394
 395         if (munmap(entry->vaddr_base, entry->size) != 0) {
 396             perror("unmap fails");
 397             exit(-1);
 398         }
 399
 400         entry->paddr_index = 0;
 401         entry->vaddr_base = NULL;
 402         entry->size = 0;
 403         g_free(entry->valid_mapping);
 404         entry->valid_mapping = NULL;
 405     }
 406
 407     mapcache->last_address_index = -1;
 408     mapcache->last_address_vaddr = NULL;
 409
 410     mapcache_unlock();
 411 }