arch/x86/kvm/cpuid.c

   1 /*
   2  * Kernel-based Virtual Machine driver for Linux
   3  * cpuid support routines
   4  *
   5  * derived from arch/x86/kvm/x86.c
   6  *
   7  * Copyright 2011 Red Hat, Inc. and/or its affiliates.
   8  * Copyright IBM Corporation, 2008
   9  *
  10  * This work is licensed under the terms of the GNU GPL, version 2.  See
  11  * the COPYING file in the top-level directory.
  12  *
  13  */
  14
  15 #include <linux/kvm_host.h>
  16 #include <linux/module.h>
  17 #include <asm/user.h>
  18 #include <asm/xsave.h>
  19 #include "cpuid.h"
  20 #include "lapic.h"
  21 #include "mmu.h"
  22 #include "trace.h"
  23
  24 void kvm_update_cpuid(struct kvm_vcpu *vcpu)
  25 {
  26         struct kvm_cpuid_entry2 *best;
  27         struct kvm_lapic *apic = vcpu->arch.apic;
  28
  29         best = kvm_find_cpuid_entry(vcpu, 1, 0);
  30         if (!best)
  31                 return;
  32
  33         /* Update OSXSAVE bit */
  34         if (cpu_has_xsave && best->function == 0x1) {
  35                 best->ecx &= ~(bit(X86_FEATURE_OSXSAVE));
  36                 if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE))
  37                         best->ecx |= bit(X86_FEATURE_OSXSAVE);
  38         }
  39
  40         if (apic) {
  41                 if (best->ecx & bit(X86_FEATURE_TSC_DEADLINE_TIMER))
  42                         apic->lapic_timer.timer_mode_mask = 3 << 17;
  43                 else
  44                         apic->lapic_timer.timer_mode_mask = 1 << 17;
  45         }
  46 }
  47
  48 static int is_efer_nx(void)
  49 {
  50         unsigned long long efer = 0;
  51
  52         rdmsrl_safe(MSR_EFER, &efer);
  53         return efer & EFER_NX;
  54 }
  55
  56 static void cpuid_fix_nx_cap(struct kvm_vcpu *vcpu)
  57 {
  58         int i;
  59         struct kvm_cpuid_entry2 *e, *entry;
  60
  61         entry = NULL;
  62         for (i = 0; i < vcpu->arch.cpuid_nent; ++i) {
  63                 e = &vcpu->arch.cpuid_entries[i];
  64                 if (e->function == 0x80000001) {
  65                         entry = e;
  66                         break;
  67                 }
  68         }
  69         if (entry && (entry->edx & (1 << 20)) && !is_efer_nx()) {
  70                 entry->edx &= ~(1 << 20);
  71                 printk(KERN_INFO "kvm: guest NX capability removed\n");
  72         }
  73 }
  74
  75 /* when an old userspace process fills a new kernel module */
  76 int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
  77                              struct kvm_cpuid *cpuid,
  78                              struct kvm_cpuid_entry __user *entries)
  79 {
  80         int r, i;
  81         struct kvm_cpuid_entry *cpuid_entries;
  82
  83         r = -E2BIG;
  84         if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
  85                 goto out;
  86         r = -ENOMEM;
  87         cpuid_entries = vmalloc(sizeof(struct kvm_cpuid_entry) * cpuid->nent);
  88         if (!cpuid_entries)
  89                 goto out;
  90         r = -EFAULT;
  91         if (copy_from_user(cpuid_entries, entries,
  92                            cpuid->nent * sizeof(struct kvm_cpuid_entry)))
  93                 goto out_free;
  94         for (i = 0; i < cpuid->nent; i++) {
  95                 vcpu->arch.cpuid_entries[i].function = cpuid_entries[i].function;
  96                 vcpu->arch.cpuid_entries[i].eax = cpuid_entries[i].eax;
  97                 vcpu->arch.cpuid_entries[i].ebx = cpuid_entries[i].ebx;
  98                 vcpu->arch.cpuid_entries[i].ecx = cpuid_entries[i].ecx;
  99                 vcpu->arch.cpuid_entries[i].edx = cpuid_entries[i].edx;
 100                 vcpu->arch.cpuid_entries[i].index = 0;
 101                 vcpu->arch.cpuid_entries[i].flags = 0;
 102                 vcpu->arch.cpuid_entries[i].padding[0] = 0;
 103                 vcpu->arch.cpuid_entries[i].padding[1] = 0;
 104                 vcpu->arch.cpuid_entries[i].padding[2] = 0;
 105         }
 106         vcpu->arch.cpuid_nent = cpuid->nent;
 107         cpuid_fix_nx_cap(vcpu);
 108         r = 0;
 109         kvm_apic_set_version(vcpu);
 110         kvm_x86_ops->cpuid_update(vcpu);
 111         kvm_update_cpuid(vcpu);
 112
 113 out_free:
 114         vfree(cpuid_entries);
 115 out:
 116         return r;
 117 }
 118
 119 int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
 120                               struct kvm_cpuid2 *cpuid,
 121                               struct kvm_cpuid_entry2 __user *entries)
 122 {
 123         int r;
 124
 125         r = -E2BIG;
 126         if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
 127                 goto out;
 128         r = -EFAULT;
 129         if (copy_from_user(&vcpu->arch.cpuid_entries, entries,
 130                            cpuid->nent * sizeof(struct kvm_cpuid_entry2)))
 131                 goto out;
 132         vcpu->arch.cpuid_nent = cpuid->nent;
 133         kvm_apic_set_version(vcpu);
 134         kvm_x86_ops->cpuid_update(vcpu);
 135         kvm_update_cpuid(vcpu);
 136         return 0;
 137
 138 out:
 139         return r;
 140 }
 141
 142 int kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu *vcpu,
 143                               struct kvm_cpuid2 *cpuid,
 144                               struct kvm_cpuid_entry2 __user *entries)
 145 {
 146         int r;
 147
 148         r = -E2BIG;
 149         if (cpuid->nent < vcpu->arch.cpuid_nent)
 150                 goto out;
 151         r = -EFAULT;
 152         if (copy_to_user(entries, &vcpu->arch.cpuid_entries,
 153                          vcpu->arch.cpuid_nent * sizeof(struct kvm_cpuid_entry2)))
 154                 goto out;
 155         return 0;
 156
 157 out:
 158         cpuid->nent = vcpu->arch.cpuid_nent;
 159         return r;
 160 }
 161
 162 static void cpuid_mask(u32 *word, int wordnum)
 163 {
 164         *word &= boot_cpu_data.x86_capability[wordnum];
 165 }
 166
 167 static void do_cpuid_1_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 168                            u32 index)
 169 {
 170         entry->function = function;
 171         entry->index = index;
 172         cpuid_count(entry->function, entry->index,
 173                     &entry->eax, &entry->ebx, &entry->ecx, &entry->edx);
 174         entry->flags = 0;
 175 }
 176
 177 static bool supported_xcr0_bit(unsigned bit)
 178 {
 179         u64 mask = ((u64)1 << bit);
 180
 181         return mask & (XSTATE_FP | XSTATE_SSE | XSTATE_YMM) & host_xcr0;
 182 }
 183
 184 #define F(x) bit(X86_FEATURE_##x)
 185
 186 static int do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 187                          u32 index, int *nent, int maxnent)
 188 {
 189         int r;
 190         unsigned f_nx = is_efer_nx() ? F(NX) : 0;
 191 #ifdef CONFIG_X86_64
 192         unsigned f_gbpages = (kvm_x86_ops->get_lpage_level() == PT_PDPE_LEVEL)
 193                                 ? F(GBPAGES) : 0;
 194         unsigned f_lm = F(LM);
 195 #else
 196         unsigned f_gbpages = 0;
 197         unsigned f_lm = 0;
 198 #endif
 199         unsigned f_rdtscp = kvm_x86_ops->rdtscp_supported() ? F(RDTSCP) : 0;
 200
 201         /* cpuid 1.edx */
 202         const u32 kvm_supported_word0_x86_features =
 203                 F(FPU) | F(VME) | F(DE) | F(PSE) |
 204                 F(TSC) | F(MSR) | F(PAE) | F(MCE) |
 205                 F(CX8) | F(APIC) | 0 /* Reserved */ | F(SEP) |
 206                 F(MTRR) | F(PGE) | F(MCA) | F(CMOV) |
 207                 F(PAT) | F(PSE36) | 0 /* PSN */ | F(CLFLSH) |
 208                 0 /* Reserved, DS, ACPI */ | F(MMX) |
 209                 F(FXSR) | F(XMM) | F(XMM2) | F(SELFSNOOP) |
 210                 0 /* HTT, TM, Reserved, PBE */;
 211         /* cpuid 0x80000001.edx */
 212         const u32 kvm_supported_word1_x86_features =
 213                 F(FPU) | F(VME) | F(DE) | F(PSE) |
 214                 F(TSC) | F(MSR) | F(PAE) | F(MCE) |
 215                 F(CX8) | F(APIC) | 0 /* Reserved */ | F(SYSCALL) |
 216                 F(MTRR) | F(PGE) | F(MCA) | F(CMOV) |
 217                 F(PAT) | F(PSE36) | 0 /* Reserved */ |
 218                 f_nx | 0 /* Reserved */ | F(MMXEXT) | F(MMX) |
 219                 F(FXSR) | F(FXSR_OPT) | f_gbpages | f_rdtscp |
 220                 0 /* Reserved */ | f_lm | F(3DNOWEXT) | F(3DNOW);
 221         /* cpuid 1.ecx */
 222         const u32 kvm_supported_word4_x86_features =
 223                 F(XMM3) | F(PCLMULQDQ) | 0 /* DTES64, MONITOR */ |
 224                 0 /* DS-CPL, VMX, SMX, EST */ |
 225                 0 /* TM2 */ | F(SSSE3) | 0 /* CNXT-ID */ | 0 /* Reserved */ |
 226                 F(FMA) | F(CX16) | 0 /* xTPR Update, PDCM */ |
 227                 0 /* Reserved, DCA */ | F(XMM4_1) |
 228                 F(XMM4_2) | F(X2APIC) | F(MOVBE) | F(POPCNT) |
 229                 0 /* Reserved*/ | F(AES) | F(XSAVE) | 0 /* OSXSAVE */ | F(AVX) |
 230                 F(F16C) | F(RDRAND);
 231         /* cpuid 0x80000001.ecx */
 232         const u32 kvm_supported_word6_x86_features =
 233                 F(LAHF_LM) | F(CMP_LEGACY) | 0 /*SVM*/ | 0 /* ExtApicSpace */ |
 234                 F(CR8_LEGACY) | F(ABM) | F(SSE4A) | F(MISALIGNSSE) |
 235                 F(3DNOWPREFETCH) | 0 /* OSVW */ | 0 /* IBS */ | F(XOP) |
 236                 0 /* SKINIT, WDT, LWP */ | F(FMA4) | F(TBM);
 237
 238         /* cpuid 0xC0000001.edx */
 239         const u32 kvm_supported_word5_x86_features =
 240                 F(XSTORE) | F(XSTORE_EN) | F(XCRYPT) | F(XCRYPT_EN) |
 241                 F(ACE2) | F(ACE2_EN) | F(PHE) | F(PHE_EN) |
 242                 F(PMM) | F(PMM_EN);
 243
 244         /* cpuid 7.0.ebx */
 245         const u32 kvm_supported_word9_x86_features =
 246                 F(FSGSBASE) | F(BMI1) | F(AVX2) | F(SMEP) | F(BMI2) | F(ERMS);
 247
 248         /* all calls to cpuid_count() should be made on the same cpu */
 249         get_cpu();
 250
 251         r = -E2BIG;
 252
 253         if (*nent >= maxnent)
 254                 goto out;
 255
 256         do_cpuid_1_ent(entry, function, index);
 257         ++*nent;
 258
 259         switch (function) {
 260         case 0:
 261                 entry->eax = min(entry->eax, (u32)0xd);
 262                 break;
 263         case 1:
 264                 entry->edx &= kvm_supported_word0_x86_features;
 265                 cpuid_mask(&entry->edx, 0);
 266                 entry->ecx &= kvm_supported_word4_x86_features;
 267                 cpuid_mask(&entry->ecx, 4);
 268                 /* we support x2apic emulation even if host does not support
 269                  * it since we emulate x2apic in software */
 270                 entry->ecx |= F(X2APIC);
 271                 break;
 272         /* function 2 entries are STATEFUL. That is, repeated cpuid commands
 273          * may return different values. This forces us to get_cpu() before
 274          * issuing the first command, and also to emulate this annoying behavior
 275          * in kvm_emulate_cpuid() using KVM_CPUID_FLAG_STATE_READ_NEXT */
 276         case 2: {
 277                 int t, times = entry->eax & 0xff;
 278
 279                 entry->flags |= KVM_CPUID_FLAG_STATEFUL_FUNC;
 280                 entry->flags |= KVM_CPUID_FLAG_STATE_READ_NEXT;
 281                 for (t = 1; t < times; ++t) {
 282                         if (*nent >= maxnent)
 283                                 goto out;
 284
 285                         do_cpuid_1_ent(&entry[t], function, 0);
 286                         entry[t].flags |= KVM_CPUID_FLAG_STATEFUL_FUNC;
 287                         ++*nent;
 288                 }
 289                 break;
 290         }
 291         /* function 4 has additional index. */
 292         case 4: {
 293                 int i, cache_type;
 294
 295                 entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
 296                 /* read more entries until cache_type is zero */
 297                 for (i = 1; ; ++i) {
 298                         if (*nent >= maxnent)
 299                                 goto out;
 300
 301                         cache_type = entry[i - 1].eax & 0x1f;
 302                         if (!cache_type)
 303                                 break;
 304                         do_cpuid_1_ent(&entry[i], function, i);
 305                         entry[i].flags |=
 306                                KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
 307                         ++*nent;
 308                 }
 309                 break;
 310         }
 311         case 7: {
 312                 entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
 313                 /* Mask ebx against host capbability word 9 */
 314                 if (index == 0) {
 315                         entry->ebx &= kvm_supported_word9_x86_features;
 316                         cpuid_mask(&entry->ebx, 9);
 317                 } else
 318                         entry->ebx = 0;
 319                 entry->eax = 0;
 320                 entry->ecx = 0;
 321                 entry->edx = 0;
 322                 break;
 323         }
 324         case 9:
 325                 break;
 326         /* function 0xb has additional index. */
 327         case 0xb: {
 328                 int i, level_type;
 329
 330                 entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
 331                 /* read more entries until level_type is zero */
 332                 for (i = 1; ; ++i) {
 333                         if (*nent >= maxnent)
 334                                 goto out;
 335
 336                         level_type = entry[i - 1].ecx & 0xff00;
 337                         if (!level_type)
 338                                 break;
 339                         do_cpuid_1_ent(&entry[i], function, i);
 340                         entry[i].flags |=
 341                                KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
 342                         ++*nent;
 343                 }
 344                 break;
 345         }
 346         case 0xd: {
 347                 int idx, i;
 348
 349                 entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
 350                 for (idx = 1, i = 1; idx < 64; ++idx) {
 351                         if (*nent >= maxnent)
 352                                 goto out;
 353
 354                         do_cpuid_1_ent(&entry[i], function, idx);
 355                         if (entry[i].eax == 0 || !supported_xcr0_bit(idx))
 356                                 continue;
 357                         entry[i].flags |=
 358                                KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
 359                         ++*nent;
 360                         ++i;
 361                 }
 362                 break;
 363         }
 364         case KVM_CPUID_SIGNATURE: {
 365                 char signature[12] = "KVMKVMKVM\0\0";
 366                 u32 *sigptr = (u32 *)signature;
 367                 entry->eax = 0;
 368                 entry->ebx = sigptr[0];
 369                 entry->ecx = sigptr[1];
 370                 entry->edx = sigptr[2];
 371                 break;
 372         }
 373         case KVM_CPUID_FEATURES:
 374                 entry->eax = (1 << KVM_FEATURE_CLOCKSOURCE) |
 375                              (1 << KVM_FEATURE_NOP_IO_DELAY) |
 376                              (1 << KVM_FEATURE_CLOCKSOURCE2) |
 377                              (1 << KVM_FEATURE_ASYNC_PF) |
 378                              (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT);
 379
 380                 if (sched_info_on())
 381                         entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);
 382
 383                 entry->ebx = 0;
 384                 entry->ecx = 0;
 385                 entry->edx = 0;
 386                 break;
 387         case 0x80000000:
 388                 entry->eax = min(entry->eax, 0x8000001a);
 389                 break;
 390         case 0x80000001:
 391                 entry->edx &= kvm_supported_word1_x86_features;
 392                 cpuid_mask(&entry->edx, 1);
 393                 entry->ecx &= kvm_supported_word6_x86_features;
 394                 cpuid_mask(&entry->ecx, 6);
 395                 break;
 396         case 0x80000008: {
 397                 unsigned g_phys_as = (entry->eax >> 16) & 0xff;
 398                 unsigned virt_as = max((entry->eax >> 8) & 0xff, 48U);
 399                 unsigned phys_as = entry->eax & 0xff;
 400
 401                 if (!g_phys_as)
 402                         g_phys_as = phys_as;
 403                 entry->eax = g_phys_as | (virt_as << 8);
 404                 entry->ebx = entry->edx = 0;
 405                 break;
 406         }
 407         case 0x80000019:
 408                 entry->ecx = entry->edx = 0;
 409                 break;
 410         case 0x8000001a:
 411                 break;
 412         case 0x8000001d:
 413                 break;
 414         /*Add support for Centaur's CPUID instruction*/
 415         case 0xC0000000:
 416                 /*Just support up to 0xC0000004 now*/
 417                 entry->eax = min(entry->eax, 0xC0000004);
 418                 break;
 419         case 0xC0000001:
 420                 entry->edx &= kvm_supported_word5_x86_features;
 421                 cpuid_mask(&entry->edx, 5);
 422                 break;
 423         case 3: /* Processor serial number */
 424         case 5: /* MONITOR/MWAIT */
 425         case 6: /* Thermal management */
 426         case 0xA: /* Architectural Performance Monitoring */
 427         case 0x80000007: /* Advanced power management */
 428         case 0xC0000002:
 429         case 0xC0000003:
 430         case 0xC0000004:
 431         default:
 432                 entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
 433                 break;
 434         }
 435
 436         kvm_x86_ops->set_supported_cpuid(function, entry);
 437
 438         r = 0;
 439
 440 out:
 441         put_cpu();
 442
 443         return r;
 444 }
 445
 446 #undef F
 447
 448 struct kvm_cpuid_param {
 449         u32 func;
 450         u32 idx;
 451         bool has_leaf_count;
 452         bool (*qualifier)(struct kvm_cpuid_param *param);
 453 };
 454
 455 static bool is_centaur_cpu(struct kvm_cpuid_param *param)
 456 {
 457         return boot_cpu_data.x86_vendor == X86_VENDOR_CENTAUR;
 458 }
 459
 460 int kvm_dev_ioctl_get_supported_cpuid(struct kvm_cpuid2 *cpuid,
 461                                       struct kvm_cpuid_entry2 __user *entries)
 462 {
 463         struct kvm_cpuid_entry2 *cpuid_entries;
 464         int limit, nent = 0, r = -E2BIG, i;
 465         u32 func;
 466         static struct kvm_cpuid_param param[] = {
 467                 { .func = 0, .has_leaf_count = true },
 468                 { .func = 0x80000000, .has_leaf_count = true },
 469                 { .func = 0xC0000000, .qualifier = is_centaur_cpu, .has_leaf_count = true },
 470                 { .func = KVM_CPUID_SIGNATURE },
 471                 { .func = KVM_CPUID_FEATURES },
 472         };
 473
 474         if (cpuid->nent < 1)
 475                 goto out;
 476         if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
 477                 cpuid->nent = KVM_MAX_CPUID_ENTRIES;
 478         r = -ENOMEM;
 479         cpuid_entries = vmalloc(sizeof(struct kvm_cpuid_entry2) * cpuid->nent);
 480         if (!cpuid_entries)
 481                 goto out;
 482
 483         r = 0;
 484         for (i = 0; i < ARRAY_SIZE(param); i++) {
 485                 struct kvm_cpuid_param *ent = &param[i];
 486
 487                 if (ent->qualifier && !ent->qualifier(ent))
 488                         continue;
 489
 490                 r = do_cpuid_ent(&cpuid_entries[nent], ent->func, ent->idx,
 491                                 &nent, cpuid->nent);
 492
 493                 if (r)
 494                         goto out_free;
 495
 496                 if (!ent->has_leaf_count)
 497                         continue;
 498
 499                 limit = cpuid_entries[nent - 1].eax;
 500                 for (func = ent->func + 1; func <= limit && nent < cpuid->nent && r == 0; ++func)
 501                         r = do_cpuid_ent(&cpuid_entries[nent], func, ent->idx,
 502                                      &nent, cpuid->nent);
 503
 504                 if (r)
 505                         goto out_free;
 506         }
 507
 508         r = -EFAULT;
 509         if (copy_to_user(entries, cpuid_entries,
 510                          nent * sizeof(struct kvm_cpuid_entry2)))
 511                 goto out_free;
 512         cpuid->nent = nent;
 513         r = 0;
 514
 515 out_free:
 516         vfree(cpuid_entries);
 517 out:
 518         return r;
 519 }
 520
 521 static int move_to_next_stateful_cpuid_entry(struct kvm_vcpu *vcpu, int i)
 522 {
 523         struct kvm_cpuid_entry2 *e = &vcpu->arch.cpuid_entries[i];
 524         int j, nent = vcpu->arch.cpuid_nent;
 525
 526         e->flags &= ~KVM_CPUID_FLAG_STATE_READ_NEXT;
 527         /* when no next entry is found, the current entry[i] is reselected */
 528         for (j = i + 1; ; j = (j + 1) % nent) {
 529                 struct kvm_cpuid_entry2 *ej = &vcpu->arch.cpuid_entries[j];
 530                 if (ej->function == e->function) {
 531                         ej->flags |= KVM_CPUID_FLAG_STATE_READ_NEXT;
 532                         return j;
 533                 }
 534         }
 535         return 0; /* silence gcc, even though control never reaches here */
 536 }
 537
 538 /* find an entry with matching function, matching index (if needed), and that
 539  * should be read next (if it's stateful) */
 540 static int is_matching_cpuid_entry(struct kvm_cpuid_entry2 *e,
 541         u32 function, u32 index)
 542 {
 543         if (e->function != function)
 544                 return 0;
 545         if ((e->flags & KVM_CPUID_FLAG_SIGNIFCANT_INDEX) && e->index != index)
 546                 return 0;
 547         if ((e->flags & KVM_CPUID_FLAG_STATEFUL_FUNC) &&
 548             !(e->flags & KVM_CPUID_FLAG_STATE_READ_NEXT))
 549                 return 0;
 550         return 1;
 551 }
 552
 553 struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
 554                                               u32 function, u32 index)
 555 {
 556         int i;
 557         struct kvm_cpuid_entry2 *best = NULL;
 558
 559         for (i = 0; i < vcpu->arch.cpuid_nent; ++i) {
 560                 struct kvm_cpuid_entry2 *e;
 561
 562                 e = &vcpu->arch.cpuid_entries[i];
 563                 if (is_matching_cpuid_entry(e, function, index)) {
 564                         if (e->flags & KVM_CPUID_FLAG_STATEFUL_FUNC)
 565                                 move_to_next_stateful_cpuid_entry(vcpu, i);
 566                         best = e;
 567                         break;
 568                 }
 569         }
 570         return best;
 571 }
 572 EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry);
 573
 574 int cpuid_maxphyaddr(struct kvm_vcpu *vcpu)
 575 {
 576         struct kvm_cpuid_entry2 *best;
 577
 578         best = kvm_find_cpuid_entry(vcpu, 0x80000000, 0);
 579         if (!best || best->eax < 0x80000008)
 580                 goto not_found;
 581         best = kvm_find_cpuid_entry(vcpu, 0x80000008, 0);
 582         if (best)
 583                 return best->eax & 0xff;
 584 not_found:
 585         return 36;
 586 }
 587
 588 /*
 589  * If no match is found, check whether we exceed the vCPU's limit
 590  * and return the content of the highest valid _standard_ leaf instead.
 591  * This is to satisfy the CPUID specification.
 592  */
 593 static struct kvm_cpuid_entry2* check_cpuid_limit(struct kvm_vcpu *vcpu,
 594                                                   u32 function, u32 index)
 595 {
 596         struct kvm_cpuid_entry2 *maxlevel;
 597
 598         maxlevel = kvm_find_cpuid_entry(vcpu, function & 0x80000000, 0);
 599         if (!maxlevel || maxlevel->eax >= function)
 600                 return NULL;
 601         if (function & 0x80000000) {
 602                 maxlevel = kvm_find_cpuid_entry(vcpu, 0, 0);
 603                 if (!maxlevel)
 604                         return NULL;
 605         }
 606         return kvm_find_cpuid_entry(vcpu, maxlevel->eax, index);
 607 }
 608
 609 void kvm_emulate_cpuid(struct kvm_vcpu *vcpu)
 610 {
 611         u32 function, index;
 612         struct kvm_cpuid_entry2 *best;
 613
 614         function = kvm_register_read(vcpu, VCPU_REGS_RAX);
 615         index = kvm_register_read(vcpu, VCPU_REGS_RCX);
 616         kvm_register_write(vcpu, VCPU_REGS_RAX, 0);
 617         kvm_register_write(vcpu, VCPU_REGS_RBX, 0);
 618         kvm_register_write(vcpu, VCPU_REGS_RCX, 0);
 619         kvm_register_write(vcpu, VCPU_REGS_RDX, 0);
 620         best = kvm_find_cpuid_entry(vcpu, function, index);
 621
 622         if (!best)
 623                 best = check_cpuid_limit(vcpu, function, index);
 624
 625         if (best) {
 626                 kvm_register_write(vcpu, VCPU_REGS_RAX, best->eax);
 627                 kvm_register_write(vcpu, VCPU_REGS_RBX, best->ebx);
 628                 kvm_register_write(vcpu, VCPU_REGS_RCX, best->ecx);
 629                 kvm_register_write(vcpu, VCPU_REGS_RDX, best->edx);
 630         }
 631         kvm_x86_ops->skip_emulated_instruction(vcpu);
 632         trace_kvm_cpuid(function,
 633                         kvm_register_read(vcpu, VCPU_REGS_RAX),
 634                         kvm_register_read(vcpu, VCPU_REGS_RBX),
 635                         kvm_register_read(vcpu, VCPU_REGS_RCX),
 636                         kvm_register_read(vcpu, VCPU_REGS_RDX));
 637 }
 638 EXPORT_SYMBOL_GPL(kvm_emulate_cpuid);