osfmk/i386/mtrr.c

   1 /*
   2  * Copyright (c) 2000-2011 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 #include <mach/kern_return.h>
  30 #include <kern/kalloc.h>
  31 #include <kern/cpu_number.h>
  32 #include <kern/cpu_data.h>
  33 #include <i386/cpuid.h>
  34 #include <i386/mp.h>
  35 #include <i386/proc_reg.h>
  36 #include <i386/mtrr.h>
  37 #include <i386/machine_check.h>
  38
  39 struct mtrr_var_range {
  40         uint64_t  base;         /* in IA32_MTRR_PHYSBASE format */
  41         uint64_t  mask;         /* in IA32_MTRR_PHYSMASK format */
  42         uint32_t  refcnt;       /* var ranges reference count */
  43 };
  44
  45 struct mtrr_fix_range {
  46         uint64_t  types;        /* fixed-range type octet */
  47 };
  48
  49 typedef struct mtrr_var_range mtrr_var_range_t;
  50 typedef struct mtrr_fix_range mtrr_fix_range_t;
  51
  52 static struct {
  53         uint64_t            MTRRcap;
  54         uint64_t            MTRRdefType;
  55         mtrr_var_range_t *  var_range;
  56         unsigned int        var_count;
  57         mtrr_fix_range_t    fix_range[11];
  58 } mtrr_state;
  59
  60 static boolean_t mtrr_initialized = FALSE;
  61
  62 decl_simple_lock_data(static, mtrr_lock);
  63 #define MTRR_LOCK()     simple_lock(&mtrr_lock);
  64 #define MTRR_UNLOCK()   simple_unlock(&mtrr_lock);
  65
  66 //#define MTRR_DEBUG 1
  67 #if     MTRR_DEBUG
  68 #define DBG(x...)       kprintf(x)
  69 #else
  70 #define DBG(x...)
  71 #endif
  72
  73 /* Private functions */
  74 static void mtrr_get_var_ranges(mtrr_var_range_t * range, int count);
  75 static void mtrr_set_var_ranges(const mtrr_var_range_t * range, int count);
  76 static void mtrr_get_fix_ranges(mtrr_fix_range_t * range);
  77 static void mtrr_set_fix_ranges(const mtrr_fix_range_t * range);
  78 static void mtrr_update_setup(void * param);
  79 static void mtrr_update_teardown(void * param);
  80 static void mtrr_update_action(void * param);
  81 static void var_range_encode(mtrr_var_range_t * range, addr64_t address,
  82                              uint64_t length, uint32_t type, int valid);
  83 static int  var_range_overlap(mtrr_var_range_t * range, addr64_t address,
  84                               uint64_t length, uint32_t type);
  85
  86 #define CACHE_CONTROL_MTRR              (NULL)
  87 #define CACHE_CONTROL_PAT               ((void *)1)
  88
  89 /*
  90  * MTRR MSR bit fields.
  91  */
  92 #define IA32_MTRR_DEF_TYPE_MT           0x000000ff
  93 #define IA32_MTRR_DEF_TYPE_FE           0x00000400
  94 #define IA32_MTRR_DEF_TYPE_E            0x00000800
  95
  96 #define IA32_MTRRCAP_VCNT               0x000000ff
  97 #define IA32_MTRRCAP_FIX                0x00000100
  98 #define IA32_MTRRCAP_WC                 0x00000400
  99
 100 /* 0 < bits <= 64 */
 101 #define PHYS_BITS_TO_MASK(bits) \
 102         ((((1ULL << (bits-1)) - 1) << 1) | 1)
 103
 104 /*
 105  * Default mask for 36 physical address bits, this can
 106  * change depending on the cpu model.
 107  */
 108 static uint64_t mtrr_phys_mask = PHYS_BITS_TO_MASK(36);
 109
 110 #define IA32_MTRR_PHYMASK_VALID         0x0000000000000800ULL
 111 #define IA32_MTRR_PHYSBASE_MASK         (mtrr_phys_mask & ~0x0000000000000FFFULL)
 112 #define IA32_MTRR_PHYSBASE_TYPE         0x00000000000000FFULL
 113
 114 /*
 115  * Variable-range mask to/from length conversions.
 116  */
 117 #define MASK_TO_LEN(mask) \
 118         ((~((mask) & IA32_MTRR_PHYSBASE_MASK) & mtrr_phys_mask) + 1)
 119
 120 #define LEN_TO_MASK(len)  \
 121         (~((len) - 1) & IA32_MTRR_PHYSBASE_MASK)
 122
 123 #define LSB(x)          ((x) & (~((x) - 1)))
 124
 125 /*
 126  * Fetch variable-range MTRR register pairs.
 127  */
 128 static void
 129 mtrr_get_var_ranges(mtrr_var_range_t * range, int count)
 130 {
 131         int i;
 132
 133         for (i = 0; i < count; i++) {
 134                 range[i].base = rdmsr64(MSR_IA32_MTRR_PHYSBASE(i));
 135                 range[i].mask = rdmsr64(MSR_IA32_MTRR_PHYSMASK(i));
 136
 137                 /* bump ref count for firmware configured ranges */
 138                 if (range[i].mask & IA32_MTRR_PHYMASK_VALID)
 139                         range[i].refcnt = 1;
 140                 else
 141                         range[i].refcnt = 0;
 142         }
 143 }
 144
 145 /*
 146  * Update variable-range MTRR register pairs.
 147  */
 148 static void
 149 mtrr_set_var_ranges(const mtrr_var_range_t * range, int count)
 150 {
 151         int i;
 152
 153         for (i = 0; i < count; i++) {
 154                 wrmsr64(MSR_IA32_MTRR_PHYSBASE(i), range[i].base);
 155                 wrmsr64(MSR_IA32_MTRR_PHYSMASK(i), range[i].mask);
 156         }
 157 }
 158
 159 /*
 160  * Fetch all fixed-range MTRR's. Note MSR offsets are not consecutive.
 161  */
 162 static void
 163 mtrr_get_fix_ranges(mtrr_fix_range_t * range)
 164 {
 165         int i;
 166
 167         /* assume 11 fix range registers */
 168         range[0].types = rdmsr64(MSR_IA32_MTRR_FIX64K_00000);
 169         range[1].types = rdmsr64(MSR_IA32_MTRR_FIX16K_80000);
 170         range[2].types = rdmsr64(MSR_IA32_MTRR_FIX16K_A0000);
 171         for (i = 0; i < 8; i++)
 172                 range[3 + i].types = rdmsr64(MSR_IA32_MTRR_FIX4K_C0000 + i);
 173 }
 174
 175 /*
 176  * Update all fixed-range MTRR's.
 177  */
 178 static void
 179 mtrr_set_fix_ranges(const struct mtrr_fix_range * range)
 180 {
 181         int i;
 182
 183         /* assume 11 fix range registers */
 184         wrmsr64(MSR_IA32_MTRR_FIX64K_00000, range[0].types);
 185         wrmsr64(MSR_IA32_MTRR_FIX16K_80000, range[1].types);
 186         wrmsr64(MSR_IA32_MTRR_FIX16K_A0000, range[2].types);
 187         for (i = 0; i < 8; i++)
 188                 wrmsr64(MSR_IA32_MTRR_FIX4K_C0000 + i, range[3 + i].types);
 189 }
 190
 191 static boolean_t
 192 mtrr_check_fix_ranges(const struct mtrr_fix_range * range)
 193 {
 194         int             i;
 195         boolean_t       match = TRUE;
 196
 197         DBG("CPU%d: %s\n", get_cpu_number(), __FUNCTION__);
 198
 199         /* assume 11 fix range registers */
 200         match = range[0].types == rdmsr64(MSR_IA32_MTRR_FIX64K_00000) &&
 201                 range[1].types == rdmsr64(MSR_IA32_MTRR_FIX16K_80000) &&
 202                 range[2].types == rdmsr64(MSR_IA32_MTRR_FIX16K_A0000);
 203         for (i = 0; match && i < 8; i++) {
 204                 match = range[3 + i].types ==
 205                         rdmsr64(MSR_IA32_MTRR_FIX4K_C0000 + i);
 206         }
 207
 208         return match;
 209 }
 210
 211 static boolean_t
 212 mtrr_check_var_ranges(mtrr_var_range_t * range, int count)
 213 {
 214         int             i;
 215         boolean_t       match = TRUE;
 216
 217         DBG("CPU%d: %s\n", get_cpu_number(), __FUNCTION__);
 218
 219         for (i = 0; match && i < count; i++) {
 220                 match = range[i].base == rdmsr64(MSR_IA32_MTRR_PHYSBASE(i)) &&
 221                         range[i].mask == rdmsr64(MSR_IA32_MTRR_PHYSMASK(i));
 222         }
 223
 224         return match;
 225 }
 226
 227 #if MTRR_DEBUG
 228 static void
 229 mtrr_msr_dump(void)
 230 {
 231         int i;
 232         int count = rdmsr64(MSR_IA32_MTRRCAP) & IA32_MTRRCAP_VCNT;
 233
 234         DBG("VAR -- BASE -------------- MASK -------------- SIZE\n");
 235         for (i = 0; i < count; i++) {
 236                 DBG(" %02x    0x%016llx  0x%016llx  0x%llx\n", i,
 237                     rdmsr64(MSR_IA32_MTRR_PHYSBASE(i)),
 238                     rdmsr64(MSR_IA32_MTRR_PHYSMASK(i)),
 239                     MASK_TO_LEN(rdmsr64(MSR_IA32_MTRR_PHYSMASK(i))));
 240         }
 241         DBG("\n");
 242
 243         DBG("FIX64K_00000: 0x%016llx\n", rdmsr64(MSR_IA32_MTRR_FIX64K_00000));
 244         DBG("FIX16K_80000: 0x%016llx\n", rdmsr64(MSR_IA32_MTRR_FIX16K_80000));
 245         DBG("FIX16K_A0000: 0x%016llx\n", rdmsr64(MSR_IA32_MTRR_FIX16K_A0000));
 246         DBG(" FIX4K_C0000: 0x%016llx\n", rdmsr64(MSR_IA32_MTRR_FIX4K_C0000));
 247         DBG(" FIX4K_C8000: 0x%016llx\n", rdmsr64(MSR_IA32_MTRR_FIX4K_C8000));
 248         DBG(" FIX4K_D0000: 0x%016llx\n", rdmsr64(MSR_IA32_MTRR_FIX4K_D0000));
 249         DBG(" FIX4K_D8000: 0x%016llx\n", rdmsr64(MSR_IA32_MTRR_FIX4K_D8000));
 250         DBG(" FIX4K_E0000: 0x%016llx\n", rdmsr64(MSR_IA32_MTRR_FIX4K_E0000));
 251         DBG(" FIX4K_E8000: 0x%016llx\n", rdmsr64(MSR_IA32_MTRR_FIX4K_E8000));
 252         DBG(" FIX4K_F0000: 0x%016llx\n", rdmsr64(MSR_IA32_MTRR_FIX4K_F0000));
 253         DBG(" FIX4K_F8000: 0x%016llx\n", rdmsr64(MSR_IA32_MTRR_FIX4K_F8000));
 254
 255         DBG("\nMTRRcap = 0x%llx MTRRdefType = 0x%llx\n",
 256             rdmsr64(MSR_IA32_MTRRCAP), rdmsr64(MSR_IA32_MTRR_DEF_TYPE));
 257 }
 258 #endif /* MTRR_DEBUG */
 259
 260 /*
 261  * Called by the boot processor (BP) early during boot to initialize MTRR
 262  * support.  The MTRR state on the BP is saved, any additional processors
 263  * will have the same settings applied to ensure MTRR consistency.
 264  */
 265 void
 266 mtrr_init(void)
 267 {
 268         /* no reason to init more than once */
 269         if (mtrr_initialized == TRUE)
 270                 return;
 271
 272         /* check for presence of MTRR feature on the processor */
 273         if ((cpuid_features() & CPUID_FEATURE_MTRR) == 0)
 274                 return;  /* no MTRR feature */
 275
 276         /* use a lock to serialize MTRR changes */
 277         bzero((void *)&mtrr_state, sizeof(mtrr_state));
 278         simple_lock_init(&mtrr_lock, 0);
 279
 280         mtrr_state.MTRRcap     = rdmsr64(MSR_IA32_MTRRCAP);
 281         mtrr_state.MTRRdefType = rdmsr64(MSR_IA32_MTRR_DEF_TYPE);
 282         mtrr_state.var_count   = (unsigned int)(mtrr_state.MTRRcap & IA32_MTRRCAP_VCNT);
 283
 284         /* allocate storage for variable ranges (can block?) */
 285         if (mtrr_state.var_count) {
 286                 mtrr_state.var_range = (mtrr_var_range_t *)
 287                                        kalloc(sizeof(mtrr_var_range_t) *
 288                                               mtrr_state.var_count);
 289                 if (mtrr_state.var_range == NULL)
 290                         mtrr_state.var_count = 0;
 291         }
 292
 293         /* fetch the initial firmware configured variable ranges */
 294         if (mtrr_state.var_count)
 295                 mtrr_get_var_ranges(mtrr_state.var_range,
 296                                     mtrr_state.var_count);
 297
 298         /* fetch the initial firmware configured fixed ranges */
 299         if (mtrr_state.MTRRcap & IA32_MTRRCAP_FIX)
 300                 mtrr_get_fix_ranges(mtrr_state.fix_range);
 301
 302         mtrr_initialized = TRUE;
 303
 304 #if MTRR_DEBUG
 305         mtrr_msr_dump();        /* dump firmware settings */
 306 #endif
 307
 308 }
 309
 310 /*
 311  * Performs the Intel recommended procedure for changing the MTRR
 312  * in a MP system. Leverage rendezvous mechanism for the required
 313  * barrier synchronization among all processors. This function is
 314  * called from the rendezvous IPI handler, and mtrr_update_cpu().
 315  */
 316 static void
 317 mtrr_update_action(void * cache_control_type)
 318 {
 319         uintptr_t cr0, cr4;
 320         uintptr_t tmp;
 321
 322         cr0 = get_cr0();
 323         cr4 = get_cr4();
 324
 325         /* enter no-fill cache mode */
 326         tmp = cr0 | CR0_CD;
 327         tmp &= ~CR0_NW;
 328         set_cr0(tmp);
 329
 330         /* flush caches */
 331         wbinvd();
 332
 333         /* clear the PGE flag in CR4 */
 334         if (cr4 & CR4_PGE)
 335                 set_cr4(cr4 & ~CR4_PGE);
 336
 337         /* flush TLBs */
 338         flush_tlb_raw();
 339
 340         if (CACHE_CONTROL_PAT == cache_control_type) {
 341                 /* Change PA6 attribute field to WC */
 342                 uint64_t pat = rdmsr64(MSR_IA32_CR_PAT);
 343                 DBG("CPU%d PAT: was 0x%016llx\n", get_cpu_number(), pat);
 344                 pat &= ~(0x0FULL << 48);
 345                 pat |=  (0x01ULL << 48);
 346                 wrmsr64(MSR_IA32_CR_PAT, pat);
 347                 DBG("CPU%d PAT: is  0x%016llx\n",
 348                     get_cpu_number(), rdmsr64(MSR_IA32_CR_PAT));
 349         }
 350         else {
 351                 /* disable all MTRR ranges */
 352                 wrmsr64(MSR_IA32_MTRR_DEF_TYPE,
 353                         mtrr_state.MTRRdefType & ~IA32_MTRR_DEF_TYPE_E);
 354
 355                 /* apply MTRR settings */
 356                 if (mtrr_state.var_count)
 357                         mtrr_set_var_ranges(mtrr_state.var_range,
 358                                         mtrr_state.var_count);
 359
 360                 if (mtrr_state.MTRRcap & IA32_MTRRCAP_FIX)
 361                         mtrr_set_fix_ranges(mtrr_state.fix_range);
 362
 363                 /* enable all MTRR range registers (what if E was not set?) */
 364                 wrmsr64(MSR_IA32_MTRR_DEF_TYPE,
 365                         mtrr_state.MTRRdefType | IA32_MTRR_DEF_TYPE_E);
 366         }
 367
 368         /* flush all caches and TLBs a second time */
 369         wbinvd();
 370         flush_tlb_raw();
 371
 372         /* restore normal cache mode */
 373         set_cr0(cr0);
 374
 375         /* restore PGE flag */
 376         if (cr4 & CR4_PGE)
 377                 set_cr4(cr4);
 378
 379         DBG("CPU%d: %s\n", get_cpu_number(), __FUNCTION__);
 380 }
 381
 382 static void
 383 mtrr_update_setup(__unused void * param_not_used)
 384 {
 385         /* disable interrupts before the first barrier */
 386         current_cpu_datap()->cpu_iflag = ml_set_interrupts_enabled(FALSE);
 387         DBG("CPU%d: %s\n", get_cpu_number(), __FUNCTION__);
 388 }
 389
 390 static void
 391 mtrr_update_teardown(__unused void * param_not_used)
 392 {
 393         /* restore interrupt flag following MTRR changes */
 394         ml_set_interrupts_enabled(current_cpu_datap()->cpu_iflag);
 395         DBG("CPU%d: %s\n", get_cpu_number(), __FUNCTION__);
 396 }
 397
 398 /*
 399  * Update MTRR settings on all processors.
 400  */
 401 kern_return_t
 402 mtrr_update_all_cpus(void)
 403 {
 404         if (mtrr_initialized == FALSE)
 405                 return KERN_NOT_SUPPORTED;
 406
 407         MTRR_LOCK();
 408         mp_rendezvous(mtrr_update_setup,
 409                       mtrr_update_action,
 410                       mtrr_update_teardown, NULL);
 411         MTRR_UNLOCK();
 412
 413         return KERN_SUCCESS;
 414 }
 415
 416 /*
 417  * Verify that a processor has been set with the BSP's MTRR settings. Called
 418  * during slave processor initialization to check and set MTRR settings
 419  * discovered on the boot processor by mtrr_init().
 420  */
 421 kern_return_t
 422 mtrr_update_cpu(void)
 423 {
 424         boolean_t       match = TRUE;
 425
 426         if (mtrr_initialized == FALSE)
 427                 return KERN_NOT_SUPPORTED;
 428
 429         DBG("CPU%d: %s\n", get_cpu_number(), __FUNCTION__);
 430
 431         MTRR_LOCK();
 432
 433         /* Check MSR_IA32_MTRR_DEF_TYPE MSR */
 434         match = mtrr_state.MTRRdefType == rdmsr64(MSR_IA32_MTRR_DEF_TYPE);
 435
 436         /* Check MSR_IA32_MTRRCAP MSR */
 437         if (match) {
 438                 match = mtrr_state.MTRRcap == rdmsr64(MSR_IA32_MTRRCAP);
 439         }
 440
 441         /* Check variable ranges */
 442         if (match && mtrr_state.var_count) {
 443                 match = mtrr_check_var_ranges(mtrr_state.var_range,
 444                                               mtrr_state.var_count);
 445         }
 446
 447         /* Check fixed ranges */
 448         if (match && (mtrr_state.MTRRcap & IA32_MTRRCAP_FIX)) {
 449                 match = mtrr_check_fix_ranges(mtrr_state.fix_range);
 450         }
 451
 452 #if MTRR_DEBUG
 453         if (!match)
 454                 mtrr_msr_dump();
 455 #endif
 456         if (!match) {
 457                 DBG("mtrr_update_cpu() setting MTRR for cpu %d\n",
 458                         get_cpu_number());
 459                 mtrr_update_action(NULL);
 460         }
 461 #if MTRR_DEBUG
 462         if (!match)
 463                 mtrr_msr_dump();
 464 #endif
 465
 466         MTRR_UNLOCK();
 467
 468         return KERN_SUCCESS;
 469 }
 470
 471 /*
 472  * Add a MTRR range to associate the physical memory range specified
 473  * with a given memory caching type.
 474  */
 475 kern_return_t
 476 mtrr_range_add(addr64_t address, uint64_t length, uint32_t type)
 477 {
 478         mtrr_var_range_t * vr;
 479         mtrr_var_range_t * free_range;
 480         kern_return_t      ret = KERN_NO_SPACE;
 481         int                overlap;
 482         unsigned int       i;
 483
 484         DBG("mtrr_range_add base = 0x%llx, size = 0x%llx, type = %d\n",
 485             address, length, type);
 486
 487         if (mtrr_initialized == FALSE) {
 488                 return KERN_NOT_SUPPORTED;
 489         }
 490
 491         /* check memory type (GPF exception for undefined types) */
 492         if ((type != MTRR_TYPE_UNCACHEABLE)  &&
 493             (type != MTRR_TYPE_WRITECOMBINE) &&
 494             (type != MTRR_TYPE_WRITETHROUGH) &&
 495             (type != MTRR_TYPE_WRITEPROTECT) &&
 496             (type != MTRR_TYPE_WRITEBACK)) {
 497                 return KERN_INVALID_ARGUMENT;
 498         }
 499
 500         /* check WC support if requested */
 501         if ((type == MTRR_TYPE_WRITECOMBINE) &&
 502             (mtrr_state.MTRRcap & IA32_MTRRCAP_WC) == 0) {
 503                 return KERN_NOT_SUPPORTED;
 504         }
 505
 506         /* leave the fix range area below 1MB alone */
 507         if (address < 0x100000 || mtrr_state.var_count == 0) {
 508                 return KERN_NOT_SUPPORTED;
 509         }
 510
 511         /*
 512          * Length must be a power of 2 given by 2^n, where n >= 12.
 513          * Base address alignment must be larger than or equal to length.
 514          */
 515         if ((length < 0x1000)       ||
 516             (LSB(length) != length) ||
 517             (address && (length > LSB(address)))) {
 518                 return KERN_INVALID_ARGUMENT;
 519         }
 520
 521         MTRR_LOCK();
 522
 523         /*
 524          * Check for overlap and locate a free range.
 525          */
 526         for (i = 0, free_range = NULL; i < mtrr_state.var_count; i++)
 527         {
 528                 vr = &mtrr_state.var_range[i];
 529
 530                 if (vr->refcnt == 0) {
 531                         /* free range candidate if no overlaps are found */
 532                         free_range = vr;
 533                         continue;
 534                 }
 535
 536                 overlap = var_range_overlap(vr, address, length, type);
 537                 if (overlap > 0) {
 538                         /*
 539                          * identical overlap permitted, increment ref count.
 540                          * no hardware update required.
 541                          */
 542                         free_range = vr;
 543                         break;
 544                 }
 545                 if (overlap < 0) {
 546                         /* unsupported overlapping of memory types */
 547                         free_range = NULL;
 548                         break;
 549                 }
 550         }
 551
 552         if (free_range) {
 553                 if (free_range->refcnt++ == 0) {
 554                         var_range_encode(free_range, address, length, type, 1);
 555                         mp_rendezvous(mtrr_update_setup,
 556                                       mtrr_update_action,
 557                                       mtrr_update_teardown, NULL);
 558                 }
 559                 ret = KERN_SUCCESS;
 560         }
 561
 562 #if MTRR_DEBUG
 563         mtrr_msr_dump();
 564 #endif
 565
 566         MTRR_UNLOCK();
 567
 568         return ret;
 569 }
 570
 571 /*
 572  * Remove a previously added MTRR range. The same arguments used for adding
 573  * the memory range must be supplied again.
 574  */
 575 kern_return_t
 576 mtrr_range_remove(addr64_t address, uint64_t length, uint32_t type)
 577 {
 578         mtrr_var_range_t * vr;
 579         int                result = KERN_FAILURE;
 580         int                cpu_update = 0;
 581         unsigned int       i;
 582
 583         DBG("mtrr_range_remove base = 0x%llx, size = 0x%llx, type = %d\n",
 584             address, length, type);
 585
 586         if (mtrr_initialized == FALSE) {
 587                 return KERN_NOT_SUPPORTED;
 588         }
 589
 590         MTRR_LOCK();
 591
 592         for (i = 0; i < mtrr_state.var_count; i++) {
 593                 vr = &mtrr_state.var_range[i];
 594
 595                 if (vr->refcnt &&
 596                     var_range_overlap(vr, address, length, type) > 0) {
 597                         /* found specified variable range */
 598                         if (--mtrr_state.var_range[i].refcnt == 0) {
 599                                 var_range_encode(vr, address, length, type, 0);
 600                                 cpu_update = 1;
 601                         }
 602                         result = KERN_SUCCESS;
 603                         break;
 604                 }
 605         }
 606
 607         if (cpu_update) {
 608                 mp_rendezvous(mtrr_update_setup,
 609                               mtrr_update_action,
 610                               mtrr_update_teardown, NULL);
 611                 result = KERN_SUCCESS;
 612         }
 613
 614 #if MTRR_DEBUG
 615         mtrr_msr_dump();
 616 #endif
 617
 618         MTRR_UNLOCK();
 619
 620         return result;
 621 }
 622
 623 /*
 624  * Variable range helper routines
 625  */
 626 static void
 627 var_range_encode(mtrr_var_range_t * range, addr64_t address,
 628                  uint64_t length, uint32_t type, int valid)
 629 {
 630         range->base = (address & IA32_MTRR_PHYSBASE_MASK) |
 631                       (type    & (uint32_t)IA32_MTRR_PHYSBASE_TYPE);
 632
 633         range->mask = LEN_TO_MASK(length) |
 634                       (valid ? IA32_MTRR_PHYMASK_VALID : 0);
 635 }
 636
 637 static int
 638 var_range_overlap(mtrr_var_range_t * range, addr64_t address,
 639                   uint64_t length, uint32_t type)
 640 {
 641         uint64_t  v_address, v_length;
 642         uint32_t  v_type;
 643         int       result = 0;  /* no overlap, or overlap ok */
 644
 645         v_address = range->base & IA32_MTRR_PHYSBASE_MASK;
 646         v_type    = (uint32_t)(range->base & IA32_MTRR_PHYSBASE_TYPE);
 647         v_length  = MASK_TO_LEN(range->mask);
 648
 649         /* detect range overlap */
 650         if ((v_address >= address && v_address < (address + length)) ||
 651             (address >= v_address && address < (v_address + v_length))) {
 652
 653                 if (v_address == address && v_length == length && v_type == type)
 654                         result = 1; /* identical overlap ok */
 655                 else if ( v_type == MTRR_TYPE_UNCACHEABLE &&
 656                             type == MTRR_TYPE_UNCACHEABLE ) {
 657                         /* UC ranges can overlap */
 658                 }
 659                 else if ((v_type == MTRR_TYPE_UNCACHEABLE &&
 660                             type == MTRR_TYPE_WRITEBACK)  ||
 661                          (v_type == MTRR_TYPE_WRITEBACK &&
 662                             type == MTRR_TYPE_UNCACHEABLE)) {
 663                         /* UC/WB can overlap - effective type becomes UC */
 664                 }
 665                 else {
 666                         /* anything else may cause undefined behavior */
 667                         result = -1;
 668                 }
 669         }
 670
 671         return result;
 672 }
 673
 674 /*
 675  * Initialize PAT (Page Attribute Table)
 676  */
 677 void
 678 pat_init(void)
 679 {
 680         boolean_t       istate;
 681         uint64_t        pat;
 682
 683         if (!(cpuid_features() & CPUID_FEATURE_PAT))
 684                 return;
 685
 686         istate = ml_set_interrupts_enabled(FALSE);
 687
 688         pat = rdmsr64(MSR_IA32_CR_PAT);
 689         DBG("CPU%d PAT: was 0x%016llx\n", get_cpu_number(), pat);
 690
 691         /* Change PA6 attribute field to WC if required */
 692         if ((pat & ~(0x0FULL << 48)) != (0x01ULL << 48)) {
 693                 mtrr_update_action(CACHE_CONTROL_PAT);
 694         }
 695         ml_set_interrupts_enabled(istate);
 696 }