arch/x86/mm/numa_64.c

   1 /*
   2  * Generic VM initialization for x86-64 NUMA setups.
   3  * Copyright 2002,2003 Andi Kleen, SuSE Labs.
   4  */
   5 #include <linux/kernel.h>
   6 #include <linux/mm.h>
   7 #include <linux/string.h>
   8 #include <linux/init.h>
   9 #include <linux/bootmem.h>
  10 #include <linux/mmzone.h>
  11 #include <linux/ctype.h>
  12 #include <linux/module.h>
  13 #include <linux/nodemask.h>
  14 #include <linux/sched.h>
  15
  16 #include <asm/e820.h>
  17 #include <asm/proto.h>
  18 #include <asm/dma.h>
  19 #include <asm/numa.h>
  20 #include <asm/acpi.h>
  21 #include <asm/k8.h>
  22
  23 #ifndef Dprintk
  24 #define Dprintk(x...)
  25 #endif
  26
  27 struct pglist_data *node_data[MAX_NUMNODES] __read_mostly;
  28 EXPORT_SYMBOL(node_data);
  29
  30 bootmem_data_t plat_node_bdata[MAX_NUMNODES];
  31
  32 struct memnode memnode;
  33
  34 int x86_cpu_to_node_map_init[NR_CPUS] = {
  35         [0 ... NR_CPUS-1] = NUMA_NO_NODE
  36 };
  37 void *x86_cpu_to_node_map_early_ptr;
  38 DEFINE_PER_CPU(int, x86_cpu_to_node_map) = NUMA_NO_NODE;
  39 EXPORT_PER_CPU_SYMBOL(x86_cpu_to_node_map);
  40 EXPORT_SYMBOL(x86_cpu_to_node_map_early_ptr);
  41
  42 s16 apicid_to_node[MAX_LOCAL_APIC] __cpuinitdata = {
  43         [0 ... MAX_LOCAL_APIC-1] = NUMA_NO_NODE
  44 };
  45
  46 cpumask_t node_to_cpumask_map[MAX_NUMNODES] __read_mostly;
  47 EXPORT_SYMBOL(node_to_cpumask_map);
  48
  49 int numa_off __initdata;
  50 unsigned long __initdata nodemap_addr;
  51 unsigned long __initdata nodemap_size;
  52
  53 /*
  54  * Given a shift value, try to populate memnodemap[]
  55  * Returns :
  56  * 1 if OK
  57  * 0 if memnodmap[] too small (of shift too small)
  58  * -1 if node overlap or lost ram (shift too big)
  59  */
  60 static int __init populate_memnodemap(const struct bootnode *nodes,
  61                                       int numnodes, int shift)
  62 {
  63         unsigned long addr, end;
  64         int i, res = -1;
  65
  66         memset(memnodemap, 0xff, sizeof(s16)*memnodemapsize);
  67         for (i = 0; i < numnodes; i++) {
  68                 addr = nodes[i].start;
  69                 end = nodes[i].end;
  70                 if (addr >= end)
  71                         continue;
  72                 if ((end >> shift) >= memnodemapsize)
  73                         return 0;
  74                 do {
  75                         if (memnodemap[addr >> shift] != NUMA_NO_NODE)
  76                                 return -1;
  77                         memnodemap[addr >> shift] = i;
  78                         addr += (1UL << shift);
  79                 } while (addr < end);
  80                 res = 1;
  81         }
  82         return res;
  83 }
  84
  85 static int __init allocate_cachealigned_memnodemap(void)
  86 {
  87         unsigned long addr;
  88
  89         memnodemap = memnode.embedded_map;
  90         if (memnodemapsize <= ARRAY_SIZE(memnode.embedded_map))
  91                 return 0;
  92
  93         addr = 0x8000;
  94         nodemap_size = round_up(sizeof(s16) * memnodemapsize, L1_CACHE_BYTES);
  95         nodemap_addr = find_e820_area(addr, end_pfn<<PAGE_SHIFT,
  96                                       nodemap_size, L1_CACHE_BYTES);
  97         if (nodemap_addr == -1UL) {
  98                 printk(KERN_ERR
  99                        "NUMA: Unable to allocate Memory to Node hash map\n");
 100                 nodemap_addr = nodemap_size = 0;
 101                 return -1;
 102         }
 103         memnodemap = phys_to_virt(nodemap_addr);
 104         reserve_early(nodemap_addr, nodemap_addr + nodemap_size, "MEMNODEMAP");
 105
 106         printk(KERN_DEBUG "NUMA: Allocated memnodemap from %lx - %lx\n",
 107                nodemap_addr, nodemap_addr + nodemap_size);
 108         return 0;
 109 }
 110
 111 /*
 112  * The LSB of all start and end addresses in the node map is the value of the
 113  * maximum possible shift.
 114  */
 115 static int __init extract_lsb_from_nodes(const struct bootnode *nodes,
 116                                          int numnodes)
 117 {
 118         int i, nodes_used = 0;
 119         unsigned long start, end;
 120         unsigned long bitfield = 0, memtop = 0;
 121
 122         for (i = 0; i < numnodes; i++) {
 123                 start = nodes[i].start;
 124                 end = nodes[i].end;
 125                 if (start >= end)
 126                         continue;
 127                 bitfield |= start;
 128                 nodes_used++;
 129                 if (end > memtop)
 130                         memtop = end;
 131         }
 132         if (nodes_used <= 1)
 133                 i = 63;
 134         else
 135                 i = find_first_bit(&bitfield, sizeof(unsigned long)*8);
 136         memnodemapsize = (memtop >> i)+1;
 137         return i;
 138 }
 139
 140 int __init compute_hash_shift(struct bootnode *nodes, int numnodes)
 141 {
 142         int shift;
 143
 144         shift = extract_lsb_from_nodes(nodes, numnodes);
 145         if (allocate_cachealigned_memnodemap())
 146                 return -1;
 147         printk(KERN_DEBUG "NUMA: Using %d for the hash shift.\n",
 148                 shift);
 149
 150         if (populate_memnodemap(nodes, numnodes, shift) != 1) {
 151                 printk(KERN_INFO "Your memory is not aligned you need to "
 152                        "rebuild your kernel with a bigger NODEMAPSIZE "
 153                        "shift=%d\n", shift);
 154                 return -1;
 155         }
 156         return shift;
 157 }
 158
 159 int early_pfn_to_nid(unsigned long pfn)
 160 {
 161         return phys_to_nid(pfn << PAGE_SHIFT);
 162 }
 163
 164 static void * __init early_node_mem(int nodeid, unsigned long start,
 165                                     unsigned long end, unsigned long size,
 166                                     unsigned long align)
 167 {
 168         unsigned long mem = find_e820_area(start, end, size, align);
 169         void *ptr;
 170
 171         if (mem != -1L)
 172                 return __va(mem);
 173
 174         ptr = __alloc_bootmem_nopanic(size, align, __pa(MAX_DMA_ADDRESS));
 175         if (ptr == NULL) {
 176                 printk(KERN_ERR "Cannot find %lu bytes in node %d\n",
 177                        size, nodeid);
 178                 return NULL;
 179         }
 180         return ptr;
 181 }
 182
 183 /* Initialize bootmem allocator for a node */
 184 void __init setup_node_bootmem(int nodeid, unsigned long start,
 185                                unsigned long end)
 186 {
 187         unsigned long start_pfn, end_pfn, bootmap_pages, bootmap_size;
 188         unsigned long bootmap_start, nodedata_phys;
 189         void *bootmap;
 190         const int pgdat_size = round_up(sizeof(pg_data_t), PAGE_SIZE);
 191
 192         start = round_up(start, ZONE_ALIGN);
 193
 194         printk(KERN_INFO "Bootmem setup node %d %016lx-%016lx\n", nodeid,
 195                start, end);
 196
 197         start_pfn = start >> PAGE_SHIFT;
 198         end_pfn = end >> PAGE_SHIFT;
 199
 200         node_data[nodeid] = early_node_mem(nodeid, start, end, pgdat_size,
 201                                            SMP_CACHE_BYTES);
 202         if (node_data[nodeid] == NULL)
 203                 return;
 204         nodedata_phys = __pa(node_data[nodeid]);
 205         printk(KERN_INFO "  NODE_DATA [%016lx - %016lx]\n", nodedata_phys,
 206                 nodedata_phys + pgdat_size - 1);
 207
 208         memset(NODE_DATA(nodeid), 0, sizeof(pg_data_t));
 209         NODE_DATA(nodeid)->bdata = &plat_node_bdata[nodeid];
 210         NODE_DATA(nodeid)->node_start_pfn = start_pfn;
 211         NODE_DATA(nodeid)->node_spanned_pages = end_pfn - start_pfn;
 212
 213         /* Find a place for the bootmem map */
 214         bootmap_pages = bootmem_bootmap_pages(end_pfn - start_pfn);
 215         bootmap_start = round_up(nodedata_phys + pgdat_size, PAGE_SIZE);
 216         /*
 217          * SMP_CAHCE_BYTES could be enough, but init_bootmem_node like
 218          * to use that to align to PAGE_SIZE
 219          */
 220         bootmap = early_node_mem(nodeid, bootmap_start, end,
 221                                  bootmap_pages<<PAGE_SHIFT, PAGE_SIZE);
 222         if (bootmap == NULL)  {
 223                 if (nodedata_phys < start || nodedata_phys >= end)
 224                         free_bootmem(nodedata_phys, pgdat_size);
 225                 node_data[nodeid] = NULL;
 226                 return;
 227         }
 228         bootmap_start = __pa(bootmap);
 229
 230         bootmap_size = init_bootmem_node(NODE_DATA(nodeid),
 231                                          bootmap_start >> PAGE_SHIFT,
 232                                          start_pfn, end_pfn);
 233
 234         printk(KERN_INFO "  bootmap [%016lx -  %016lx] pages %lx\n",
 235                  bootmap_start, bootmap_start + bootmap_size - 1,
 236                  bootmap_pages);
 237
 238         free_bootmem_with_active_regions(nodeid, end);
 239
 240         reserve_bootmem_node(NODE_DATA(nodeid), nodedata_phys, pgdat_size,
 241                         BOOTMEM_DEFAULT);
 242         reserve_bootmem_node(NODE_DATA(nodeid), bootmap_start,
 243                         bootmap_pages<<PAGE_SHIFT, BOOTMEM_DEFAULT);
 244 #ifdef CONFIG_ACPI_NUMA
 245         srat_reserve_add_area(nodeid);
 246 #endif
 247         node_set_online(nodeid);
 248 }
 249
 250 /*
 251  * There are unfortunately some poorly designed mainboards around that
 252  * only connect memory to a single CPU. This breaks the 1:1 cpu->node
 253  * mapping. To avoid this fill in the mapping for all possible CPUs,
 254  * as the number of CPUs is not known yet. We round robin the existing
 255  * nodes.
 256  */
 257 void __init numa_init_array(void)
 258 {
 259         int rr, i;
 260
 261         rr = first_node(node_online_map);
 262         for (i = 0; i < NR_CPUS; i++) {
 263                 if (early_cpu_to_node(i) != NUMA_NO_NODE)
 264                         continue;
 265                 numa_set_node(i, rr);
 266                 rr = next_node(rr, node_online_map);
 267                 if (rr == MAX_NUMNODES)
 268                         rr = first_node(node_online_map);
 269         }
 270 }
 271
 272 #ifdef CONFIG_NUMA_EMU
 273 /* Numa emulation */
 274 char *cmdline __initdata;
 275
 276 /*
 277  * Setups up nid to range from addr to addr + size.  If the end
 278  * boundary is greater than max_addr, then max_addr is used instead.
 279  * The return value is 0 if there is additional memory left for
 280  * allocation past addr and -1 otherwise.  addr is adjusted to be at
 281  * the end of the node.
 282  */
 283 static int __init setup_node_range(int nid, struct bootnode *nodes, u64 *addr,
 284                                    u64 size, u64 max_addr)
 285 {
 286         int ret = 0;
 287
 288         nodes[nid].start = *addr;
 289         *addr += size;
 290         if (*addr >= max_addr) {
 291                 *addr = max_addr;
 292                 ret = -1;
 293         }
 294         nodes[nid].end = *addr;
 295         node_set(nid, node_possible_map);
 296         printk(KERN_INFO "Faking node %d at %016Lx-%016Lx (%LuMB)\n", nid,
 297                nodes[nid].start, nodes[nid].end,
 298                (nodes[nid].end - nodes[nid].start) >> 20);
 299         return ret;
 300 }
 301
 302 /*
 303  * Splits num_nodes nodes up equally starting at node_start.  The return value
 304  * is the number of nodes split up and addr is adjusted to be at the end of the
 305  * last node allocated.
 306  */
 307 static int __init split_nodes_equally(struct bootnode *nodes, u64 *addr,
 308                                       u64 max_addr, int node_start,
 309                                       int num_nodes)
 310 {
 311         unsigned int big;
 312         u64 size;
 313         int i;
 314
 315         if (num_nodes <= 0)
 316                 return -1;
 317         if (num_nodes > MAX_NUMNODES)
 318                 num_nodes = MAX_NUMNODES;
 319         size = (max_addr - *addr - e820_hole_size(*addr, max_addr)) /
 320                num_nodes;
 321         /*
 322          * Calculate the number of big nodes that can be allocated as a result
 323          * of consolidating the leftovers.
 324          */
 325         big = ((size & ~FAKE_NODE_MIN_HASH_MASK) * num_nodes) /
 326               FAKE_NODE_MIN_SIZE;
 327
 328         /* Round down to nearest FAKE_NODE_MIN_SIZE. */
 329         size &= FAKE_NODE_MIN_HASH_MASK;
 330         if (!size) {
 331                 printk(KERN_ERR "Not enough memory for each node.  "
 332                        "NUMA emulation disabled.\n");
 333                 return -1;
 334         }
 335
 336         for (i = node_start; i < num_nodes + node_start; i++) {
 337                 u64 end = *addr + size;
 338
 339                 if (i < big)
 340                         end += FAKE_NODE_MIN_SIZE;
 341                 /*
 342                  * The final node can have the remaining system RAM.  Other
 343                  * nodes receive roughly the same amount of available pages.
 344                  */
 345                 if (i == num_nodes + node_start - 1)
 346                         end = max_addr;
 347                 else
 348                         while (end - *addr - e820_hole_size(*addr, end) <
 349                                size) {
 350                                 end += FAKE_NODE_MIN_SIZE;
 351                                 if (end > max_addr) {
 352                                         end = max_addr;
 353                                         break;
 354                                 }
 355                         }
 356                 if (setup_node_range(i, nodes, addr, end - *addr, max_addr) < 0)
 357                         break;
 358         }
 359         return i - node_start + 1;
 360 }
 361
 362 /*
 363  * Splits the remaining system RAM into chunks of size.  The remaining memory is
 364  * always assigned to a final node and can be asymmetric.  Returns the number of
 365  * nodes split.
 366  */
 367 static int __init split_nodes_by_size(struct bootnode *nodes, u64 *addr,
 368                                       u64 max_addr, int node_start, u64 size)
 369 {
 370         int i = node_start;
 371         size = (size << 20) & FAKE_NODE_MIN_HASH_MASK;
 372         while (!setup_node_range(i++, nodes, addr, size, max_addr))
 373                 ;
 374         return i - node_start;
 375 }
 376
 377 /*
 378  * Sets up the system RAM area from start_pfn to end_pfn according to the
 379  * numa=fake command-line option.
 380  */
 381 static int __init numa_emulation(unsigned long start_pfn, unsigned long end_pfn)
 382 {
 383         struct bootnode nodes[MAX_NUMNODES];
 384         u64 size, addr = start_pfn << PAGE_SHIFT;
 385         u64 max_addr = end_pfn << PAGE_SHIFT;
 386         int num_nodes = 0, num = 0, coeff_flag, coeff = -1, i;
 387
 388         memset(&nodes, 0, sizeof(nodes));
 389         /*
 390          * If the numa=fake command-line is just a single number N, split the
 391          * system RAM into N fake nodes.
 392          */
 393         if (!strchr(cmdline, '*') && !strchr(cmdline, ',')) {
 394                 long n = simple_strtol(cmdline, NULL, 0);
 395
 396                 num_nodes = split_nodes_equally(nodes, &addr, max_addr, 0, n);
 397                 if (num_nodes < 0)
 398                         return num_nodes;
 399                 goto out;
 400         }
 401
 402         /* Parse the command line. */
 403         for (coeff_flag = 0; ; cmdline++) {
 404                 if (*cmdline && isdigit(*cmdline)) {
 405                         num = num * 10 + *cmdline - '0';
 406                         continue;
 407                 }
 408                 if (*cmdline == '*') {
 409                         if (num > 0)
 410                                 coeff = num;
 411                         coeff_flag = 1;
 412                 }
 413                 if (!*cmdline || *cmdline == ',') {
 414                         if (!coeff_flag)
 415                                 coeff = 1;
 416                         /*
 417                          * Round down to the nearest FAKE_NODE_MIN_SIZE.
 418                          * Command-line coefficients are in megabytes.
 419                          */
 420                         size = ((u64)num << 20) & FAKE_NODE_MIN_HASH_MASK;
 421                         if (size)
 422                                 for (i = 0; i < coeff; i++, num_nodes++)
 423                                         if (setup_node_range(num_nodes, nodes,
 424                                                 &addr, size, max_addr) < 0)
 425                                                 goto done;
 426                         if (!*cmdline)
 427                                 break;
 428                         coeff_flag = 0;
 429                         coeff = -1;
 430                 }
 431                 num = 0;
 432         }
 433 done:
 434         if (!num_nodes)
 435                 return -1;
 436         /* Fill remainder of system RAM, if appropriate. */
 437         if (addr < max_addr) {
 438                 if (coeff_flag && coeff < 0) {
 439                         /* Split remaining nodes into num-sized chunks */
 440                         num_nodes += split_nodes_by_size(nodes, &addr, max_addr,
 441                                                          num_nodes, num);
 442                         goto out;
 443                 }
 444                 switch (*(cmdline - 1)) {
 445                 case '*':
 446                         /* Split remaining nodes into coeff chunks */
 447                         if (coeff <= 0)
 448                                 break;
 449                         num_nodes += split_nodes_equally(nodes, &addr, max_addr,
 450                                                          num_nodes, coeff);
 451                         break;
 452                 case ',':
 453                         /* Do not allocate remaining system RAM */
 454                         break;
 455                 default:
 456                         /* Give one final node */
 457                         setup_node_range(num_nodes, nodes, &addr,
 458                                          max_addr - addr, max_addr);
 459                         num_nodes++;
 460                 }
 461         }
 462 out:
 463         memnode_shift = compute_hash_shift(nodes, num_nodes);
 464         if (memnode_shift < 0) {
 465                 memnode_shift = 0;
 466                 printk(KERN_ERR "No NUMA hash function found.  NUMA emulation "
 467                        "disabled.\n");
 468                 return -1;
 469         }
 470
 471         /*
 472          * We need to vacate all active ranges that may have been registered by
 473          * SRAT and set acpi_numa to -1 so that srat_disabled() always returns
 474          * true.  NUMA emulation has succeeded so we will not scan ACPI nodes.
 475          */
 476         remove_all_active_ranges();
 477 #ifdef CONFIG_ACPI_NUMA
 478         acpi_numa = -1;
 479 #endif
 480         for_each_node_mask(i, node_possible_map) {
 481                 e820_register_active_regions(i, nodes[i].start >> PAGE_SHIFT,
 482                                                 nodes[i].end >> PAGE_SHIFT);
 483                 setup_node_bootmem(i, nodes[i].start, nodes[i].end);
 484         }
 485         acpi_fake_nodes(nodes, num_nodes);
 486         numa_init_array();
 487         return 0;
 488 }
 489 #endif /* CONFIG_NUMA_EMU */
 490
 491 void __init numa_initmem_init(unsigned long start_pfn, unsigned long end_pfn)
 492 {
 493         int i;
 494
 495         nodes_clear(node_possible_map);
 496         nodes_clear(node_online_map);
 497
 498 #ifdef CONFIG_NUMA_EMU
 499         if (cmdline && !numa_emulation(start_pfn, end_pfn))
 500                 return;
 501         nodes_clear(node_possible_map);
 502         nodes_clear(node_online_map);
 503 #endif
 504
 505 #ifdef CONFIG_ACPI_NUMA
 506         if (!numa_off && !acpi_scan_nodes(start_pfn << PAGE_SHIFT,
 507                                           end_pfn << PAGE_SHIFT))
 508                 return;
 509         nodes_clear(node_possible_map);
 510         nodes_clear(node_online_map);
 511 #endif
 512
 513 #ifdef CONFIG_K8_NUMA
 514         if (!numa_off && !k8_scan_nodes(start_pfn<<PAGE_SHIFT,
 515                                         end_pfn<<PAGE_SHIFT))
 516                 return;
 517         nodes_clear(node_possible_map);
 518         nodes_clear(node_online_map);
 519 #endif
 520         printk(KERN_INFO "%s\n",
 521                numa_off ? "NUMA turned off" : "No NUMA configuration found");
 522
 523         printk(KERN_INFO "Faking a node at %016lx-%016lx\n",
 524                start_pfn << PAGE_SHIFT,
 525                end_pfn << PAGE_SHIFT);
 526         /* setup dummy node covering all memory */
 527         memnode_shift = 63;
 528         memnodemap = memnode.embedded_map;
 529         memnodemap[0] = 0;
 530         node_set_online(0);
 531         node_set(0, node_possible_map);
 532         for (i = 0; i < NR_CPUS; i++)
 533                 numa_set_node(i, 0);
 534         /* cpumask_of_cpu() may not be available during early startup */
 535         memset(&node_to_cpumask_map[0], 0, sizeof(node_to_cpumask_map[0]));
 536         cpu_set(0, node_to_cpumask_map[0]);
 537         e820_register_active_regions(0, start_pfn, end_pfn);
 538         setup_node_bootmem(0, start_pfn << PAGE_SHIFT, end_pfn << PAGE_SHIFT);
 539 }
 540
 541 __cpuinit void numa_add_cpu(int cpu)
 542 {
 543         set_bit(cpu,
 544                 (unsigned long *)&node_to_cpumask_map[early_cpu_to_node(cpu)]);
 545 }
 546
 547 void __cpuinit numa_set_node(int cpu, int node)
 548 {
 549         int *cpu_to_node_map = x86_cpu_to_node_map_early_ptr;
 550
 551         if(cpu_to_node_map)
 552                 cpu_to_node_map[cpu] = node;
 553         else if(per_cpu_offset(cpu))
 554                 per_cpu(x86_cpu_to_node_map, cpu) = node;
 555         else
 556                 Dprintk(KERN_INFO "Setting node for non-present cpu %d\n", cpu);
 557 }
 558
 559 unsigned long __init numa_free_all_bootmem(void)
 560 {
 561         unsigned long pages = 0;
 562         int i;
 563
 564         for_each_online_node(i)
 565                 pages += free_all_bootmem_node(NODE_DATA(i));
 566
 567         return pages;
 568 }
 569
 570 void __init paging_init(void)
 571 {
 572         unsigned long max_zone_pfns[MAX_NR_ZONES];
 573
 574         memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
 575         max_zone_pfns[ZONE_DMA] = MAX_DMA_PFN;
 576         max_zone_pfns[ZONE_DMA32] = MAX_DMA32_PFN;
 577         max_zone_pfns[ZONE_NORMAL] = end_pfn;
 578
 579         sparse_memory_present_with_active_regions(MAX_NUMNODES);
 580         sparse_init();
 581
 582         free_area_init_nodes(max_zone_pfns);
 583 }
 584
 585 static __init int numa_setup(char *opt)
 586 {
 587         if (!opt)
 588                 return -EINVAL;
 589         if (!strncmp(opt, "off", 3))
 590                 numa_off = 1;
 591 #ifdef CONFIG_NUMA_EMU
 592         if (!strncmp(opt, "fake=", 5))
 593                 cmdline = opt + 5;
 594 #endif
 595 #ifdef CONFIG_ACPI_NUMA
 596         if (!strncmp(opt, "noacpi", 6))
 597                 acpi_numa = -1;
 598         if (!strncmp(opt, "hotadd=", 7))
 599                 hotadd_percent = simple_strtoul(opt+7, NULL, 10);
 600 #endif
 601         return 0;
 602 }
 603 early_param("numa", numa_setup);
 604
 605 /*
 606  * Setup early cpu_to_node.
 607  *
 608  * Populate cpu_to_node[] only if x86_cpu_to_apicid[],
 609  * and apicid_to_node[] tables have valid entries for a CPU.
 610  * This means we skip cpu_to_node[] initialisation for NUMA
 611  * emulation and faking node case (when running a kernel compiled
 612  * for NUMA on a non NUMA box), which is OK as cpu_to_node[]
 613  * is already initialized in a round robin manner at numa_init_array,
 614  * prior to this call, and this initialization is good enough
 615  * for the fake NUMA cases.
 616  */
 617 void __init init_cpu_to_node(void)
 618 {
 619         int i;
 620
 621         for (i = 0; i < NR_CPUS; i++) {
 622                 int node;
 623                 u16 apicid = x86_cpu_to_apicid_init[i];
 624
 625                 if (apicid == BAD_APICID)
 626                         continue;
 627                 node = apicid_to_node[apicid];
 628                 if (node == NUMA_NO_NODE)
 629                         continue;
 630                 if (!node_online(node))
 631                         continue;
 632                 numa_set_node(i, node);
 633         }
 634 }
 635
 636