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  */
   8
   9 #include "config.h"
  10
  11 #include <sys/resource.h>
  12
  13 #include "hw/xen_backend.h"
  14 #include "blockdev.h"
  15 #include "bitmap.h"
  16
  17 #include <xen/hvm/params.h>
  18 #include <sys/mman.h>
  19
  20 #include "xen-mapcache.h"
  21 #include "trace.h"
  22
  23
  24 //#define MAPCACHE_DEBUG
  25
  26 #ifdef MAPCACHE_DEBUG
  27 #  define DPRINTF(fmt, ...) do { \
  28     fprintf(stderr, "xen_mapcache: " fmt, ## __VA_ARGS__); \
  29 } while (0)
  30 #else
  31 #  define DPRINTF(fmt, ...) do { } while (0)
  32 #endif
  33
  34 #if defined(__i386__)
  35 #  define MCACHE_BUCKET_SHIFT 16
  36 #  define MCACHE_MAX_SIZE     (1UL<<31) /* 2GB Cap */
  37 #elif defined(__x86_64__)
  38 #  define MCACHE_BUCKET_SHIFT 20
  39 #  define MCACHE_MAX_SIZE     (1UL<<35) /* 32GB Cap */
  40 #endif
  41 #define MCACHE_BUCKET_SIZE (1UL << MCACHE_BUCKET_SHIFT)
  42
  43 #define mapcache_lock()   ((void)0)
  44 #define mapcache_unlock() ((void)0)
  45
  46 typedef struct MapCacheEntry {
  47     target_phys_addr_t paddr_index;
  48     uint8_t *vaddr_base;
  49     unsigned long *valid_mapping;
  50     uint8_t lock;
  51     target_phys_addr_t size;
  52     struct MapCacheEntry *next;
  53 } MapCacheEntry;
  54
  55 typedef struct MapCacheRev {
  56     uint8_t *vaddr_req;
  57     target_phys_addr_t paddr_index;
  58     target_phys_addr_t size;
  59     QTAILQ_ENTRY(MapCacheRev) next;
  60 } MapCacheRev;
  61
  62 typedef struct MapCache {
  63     MapCacheEntry *entry;
  64     unsigned long nr_buckets;
  65     QTAILQ_HEAD(map_cache_head, MapCacheRev) locked_entries;
  66
  67     /* For most cases (>99.9%), the page address is the same. */
  68     target_phys_addr_t last_address_index;
  69     uint8_t *last_address_vaddr;
  70     unsigned long max_mcache_size;
  71     unsigned int mcache_bucket_shift;
  72 } MapCache;
  73
  74 static MapCache *mapcache;
  75
  76 static inline int test_bits(int nr, int size, const unsigned long *addr)
  77 {
  78     unsigned long res = find_next_zero_bit(addr, size + nr, nr);
  79     if (res >= nr + size)
  80         return 1;
  81     else
  82         return 0;
  83 }
  84
  85 void xen_map_cache_init(void)
  86 {
  87     unsigned long size;
  88     struct rlimit rlimit_as;
  89
  90     mapcache = qemu_mallocz(sizeof (MapCache));
  91
  92     QTAILQ_INIT(&mapcache->locked_entries);
  93     mapcache->last_address_index = -1;
  94
  95     getrlimit(RLIMIT_AS, &rlimit_as);
  96     if (rlimit_as.rlim_max < MCACHE_MAX_SIZE) {
  97         rlimit_as.rlim_cur = rlimit_as.rlim_max;
  98     } else {
  99         rlimit_as.rlim_cur = MCACHE_MAX_SIZE;
 100     }
 101
 102     setrlimit(RLIMIT_AS, &rlimit_as);
 103     mapcache->max_mcache_size = rlimit_as.rlim_cur;
 104
 105     mapcache->nr_buckets =
 106         (((mapcache->max_mcache_size >> XC_PAGE_SHIFT) +
 107           (1UL << (MCACHE_BUCKET_SHIFT - XC_PAGE_SHIFT)) - 1) >>
 108          (MCACHE_BUCKET_SHIFT - XC_PAGE_SHIFT));
 109
 110     size = mapcache->nr_buckets * sizeof (MapCacheEntry);
 111     size = (size + XC_PAGE_SIZE - 1) & ~(XC_PAGE_SIZE - 1);
 112     DPRINTF("%s, nr_buckets = %lx size %lu\n", __func__,
 113             mapcache->nr_buckets, size);
 114     mapcache->entry = qemu_mallocz(size);
 115 }
 116
 117 static void xen_remap_bucket(MapCacheEntry *entry,
 118                              target_phys_addr_t size,
 119                              target_phys_addr_t address_index)
 120 {
 121     uint8_t *vaddr_base;
 122     xen_pfn_t *pfns;
 123     int *err;
 124     unsigned int i;
 125     target_phys_addr_t nb_pfn = size >> XC_PAGE_SHIFT;
 126
 127     trace_xen_remap_bucket(address_index);
 128
 129     pfns = qemu_mallocz(nb_pfn * sizeof (xen_pfn_t));
 130     err = qemu_mallocz(nb_pfn * sizeof (int));
 131
 132     if (entry->vaddr_base != NULL) {
 133         if (munmap(entry->vaddr_base, entry->size) != 0) {
 134             perror("unmap fails");
 135             exit(-1);
 136         }
 137     }
 138     if (entry->valid_mapping != NULL) {
 139         qemu_free(entry->valid_mapping);
 140         entry->valid_mapping = NULL;
 141     }
 142
 143     for (i = 0; i < nb_pfn; i++) {
 144         pfns[i] = (address_index << (MCACHE_BUCKET_SHIFT-XC_PAGE_SHIFT)) + i;
 145     }
 146
 147     vaddr_base = xc_map_foreign_bulk(xen_xc, xen_domid, PROT_READ|PROT_WRITE,
 148                                      pfns, err, nb_pfn);
 149     if (vaddr_base == NULL) {
 150         perror("xc_map_foreign_bulk");
 151         exit(-1);
 152     }
 153
 154     entry->vaddr_base = vaddr_base;
 155     entry->paddr_index = address_index;
 156     entry->size = size;
 157     entry->valid_mapping = (unsigned long *) qemu_mallocz(sizeof(unsigned long) *
 158             BITS_TO_LONGS(size >> XC_PAGE_SHIFT));
 159
 160     bitmap_zero(entry->valid_mapping, nb_pfn);
 161     for (i = 0; i < nb_pfn; i++) {
 162         if (!err[i]) {
 163             bitmap_set(entry->valid_mapping, i, 1);
 164         }
 165     }
 166
 167     qemu_free(pfns);
 168     qemu_free(err);
 169 }
 170
 171 uint8_t *xen_map_cache(target_phys_addr_t phys_addr, target_phys_addr_t size,
 172                        uint8_t lock)
 173 {
 174     MapCacheEntry *entry, *pentry = NULL;
 175     target_phys_addr_t address_index  = phys_addr >> MCACHE_BUCKET_SHIFT;
 176     target_phys_addr_t address_offset = phys_addr & (MCACHE_BUCKET_SIZE - 1);
 177     target_phys_addr_t __size = size;
 178
 179     trace_xen_map_cache(phys_addr);
 180
 181     if (address_index == mapcache->last_address_index && !lock && !__size) {
 182         trace_xen_map_cache_return(mapcache->last_address_vaddr + address_offset);
 183         return mapcache->last_address_vaddr + address_offset;
 184     }
 185
 186     /* size is always a multiple of MCACHE_BUCKET_SIZE */
 187     if ((address_offset + (__size % MCACHE_BUCKET_SIZE)) > MCACHE_BUCKET_SIZE)
 188         __size += MCACHE_BUCKET_SIZE;
 189     if (__size % MCACHE_BUCKET_SIZE)
 190         __size += MCACHE_BUCKET_SIZE - (__size % MCACHE_BUCKET_SIZE);
 191     if (!__size)
 192         __size = MCACHE_BUCKET_SIZE;
 193
 194     entry = &mapcache->entry[address_index % mapcache->nr_buckets];
 195
 196     while (entry && entry->lock && entry->vaddr_base &&
 197             (entry->paddr_index != address_index || entry->size != __size ||
 198              !test_bits(address_offset >> XC_PAGE_SHIFT, size >> XC_PAGE_SHIFT,
 199                  entry->valid_mapping))) {
 200         pentry = entry;
 201         entry = entry->next;
 202     }
 203     if (!entry) {
 204         entry = qemu_mallocz(sizeof (MapCacheEntry));
 205         pentry->next = entry;
 206         xen_remap_bucket(entry, __size, address_index);
 207     } else if (!entry->lock) {
 208         if (!entry->vaddr_base || entry->paddr_index != address_index ||
 209                 entry->size != __size ||
 210                 !test_bits(address_offset >> XC_PAGE_SHIFT, size >> XC_PAGE_SHIFT,
 211                     entry->valid_mapping)) {
 212             xen_remap_bucket(entry, __size, address_index);
 213         }
 214     }
 215
 216     if(!test_bits(address_offset >> XC_PAGE_SHIFT, size >> XC_PAGE_SHIFT,
 217                 entry->valid_mapping)) {
 218         mapcache->last_address_index = -1;
 219         trace_xen_map_cache_return(NULL);
 220         return NULL;
 221     }
 222
 223     mapcache->last_address_index = address_index;
 224     mapcache->last_address_vaddr = entry->vaddr_base;
 225     if (lock) {
 226         MapCacheRev *reventry = qemu_mallocz(sizeof(MapCacheRev));
 227         entry->lock++;
 228         reventry->vaddr_req = mapcache->last_address_vaddr + address_offset;
 229         reventry->paddr_index = mapcache->last_address_index;
 230         reventry->size = entry->size;
 231         QTAILQ_INSERT_HEAD(&mapcache->locked_entries, reventry, next);
 232     }
 233
 234     trace_xen_map_cache_return(mapcache->last_address_vaddr + address_offset);
 235     return mapcache->last_address_vaddr + address_offset;
 236 }
 237
 238 ram_addr_t xen_ram_addr_from_mapcache(void *ptr)
 239 {
 240     MapCacheEntry *entry = NULL;
 241     MapCacheRev *reventry;
 242     target_phys_addr_t paddr_index;
 243     target_phys_addr_t size;
 244     int found = 0;
 245
 246     QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 247         if (reventry->vaddr_req == ptr) {
 248             paddr_index = reventry->paddr_index;
 249             size = reventry->size;
 250             found = 1;
 251             break;
 252         }
 253     }
 254     if (!found) {
 255         fprintf(stderr, "%s, could not find %p\n", __func__, ptr);
 256         QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 257             DPRINTF("   "TARGET_FMT_plx" -> %p is present\n", reventry->paddr_index,
 258                     reventry->vaddr_req);
 259         }
 260         abort();
 261         return 0;
 262     }
 263
 264     entry = &mapcache->entry[paddr_index % mapcache->nr_buckets];
 265     while (entry && (entry->paddr_index != paddr_index || entry->size != size)) {
 266         entry = entry->next;
 267     }
 268     if (!entry) {
 269         DPRINTF("Trying to find address %p that is not in the mapcache!\n", ptr);
 270         return 0;
 271     }
 272     return (reventry->paddr_index << MCACHE_BUCKET_SHIFT) +
 273         ((unsigned long) ptr - (unsigned long) entry->vaddr_base);
 274 }
 275
 276 void xen_invalidate_map_cache_entry(uint8_t *buffer)
 277 {
 278     MapCacheEntry *entry = NULL, *pentry = NULL;
 279     MapCacheRev *reventry;
 280     target_phys_addr_t paddr_index;
 281     target_phys_addr_t size;
 282     int found = 0;
 283
 284     if (mapcache->last_address_vaddr == buffer) {
 285         mapcache->last_address_index = -1;
 286     }
 287
 288     QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 289         if (reventry->vaddr_req == buffer) {
 290             paddr_index = reventry->paddr_index;
 291             size = reventry->size;
 292             found = 1;
 293             break;
 294         }
 295     }
 296     if (!found) {
 297         DPRINTF("%s, could not find %p\n", __func__, buffer);
 298         QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 299             DPRINTF("   "TARGET_FMT_plx" -> %p is present\n", reventry->paddr_index, reventry->vaddr_req);
 300         }
 301         return;
 302     }
 303     QTAILQ_REMOVE(&mapcache->locked_entries, reventry, next);
 304     qemu_free(reventry);
 305
 306     entry = &mapcache->entry[paddr_index % mapcache->nr_buckets];
 307     while (entry && (entry->paddr_index != paddr_index || entry->size != size)) {
 308         pentry = entry;
 309         entry = entry->next;
 310     }
 311     if (!entry) {
 312         DPRINTF("Trying to unmap address %p that is not in the mapcache!\n", buffer);
 313         return;
 314     }
 315     entry->lock--;
 316     if (entry->lock > 0 || pentry == NULL) {
 317         return;
 318     }
 319
 320     pentry->next = entry->next;
 321     if (munmap(entry->vaddr_base, entry->size) != 0) {
 322         perror("unmap fails");
 323         exit(-1);
 324     }
 325     qemu_free(entry->valid_mapping);
 326     qemu_free(entry);
 327 }
 328
 329 void xen_invalidate_map_cache(void)
 330 {
 331     unsigned long i;
 332     MapCacheRev *reventry;
 333
 334     /* Flush pending AIO before destroying the mapcache */
 335     qemu_aio_flush();
 336
 337     QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
 338         DPRINTF("There should be no locked mappings at this time, "
 339                 "but "TARGET_FMT_plx" -> %p is present\n",
 340                 reventry->paddr_index, reventry->vaddr_req);
 341     }
 342
 343     mapcache_lock();
 344
 345     for (i = 0; i < mapcache->nr_buckets; i++) {
 346         MapCacheEntry *entry = &mapcache->entry[i];
 347
 348         if (entry->vaddr_base == NULL) {
 349             continue;
 350         }
 351
 352         if (munmap(entry->vaddr_base, entry->size) != 0) {
 353             perror("unmap fails");
 354             exit(-1);
 355         }
 356
 357         entry->paddr_index = 0;
 358         entry->vaddr_base = NULL;
 359         entry->size = 0;
 360         qemu_free(entry->valid_mapping);
 361         entry->valid_mapping = NULL;
 362     }
 363
 364     mapcache->last_address_index = -1;
 365     mapcache->last_address_vaddr = NULL;
 366
 367     mapcache_unlock();
 368 }