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 <linux/vmalloc.h>
  18 #include <linux/uaccess.h>
  19 #include <asm/user.h>
  20 #include <asm/xsave.h>
  21 #include "cpuid.h"
  22 #include "lapic.h"
  23 #include "mmu.h"
  24 #include "trace.h"
  25
  26 void kvm_update_cpuid(struct kvm_vcpu *vcpu)
  27 {
  28         struct kvm_cpuid_entry2 *best;
  29         struct kvm_lapic *apic = vcpu->arch.apic;
  30
  31         best = kvm_find_cpuid_entry(vcpu, 1, 0);
  32         if (!best)
  33                 return;
  34
  35         /* Update OSXSAVE bit */
  36         if (cpu_has_xsave && best->function == 0x1) {
  37                 best->ecx &= ~(bit(X86_FEATURE_OSXSAVE));
  38                 if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE))
  39                         best->ecx |= bit(X86_FEATURE_OSXSAVE);
  40         }
  41
  42         if (apic) {
  43                 if (best->ecx & bit(X86_FEATURE_TSC_DEADLINE_TIMER))
  44                         apic->lapic_timer.timer_mode_mask = 3 << 17;
  45                 else
  46                         apic->lapic_timer.timer_mode_mask = 1 << 17;
  47         }
  48
  49         best = kvm_find_cpuid_entry(vcpu, 0xD, 0);
  50         if (!best)
  51                 vcpu->arch.guest_supported_xcr0 = 0;
  52         else
  53                 vcpu->arch.guest_supported_xcr0 =
  54                         (best->eax | ((u64)best->edx << 32)) &
  55                         host_xcr0 & KVM_SUPPORTED_XCR0;
  56
  57         kvm_pmu_cpuid_update(vcpu);
  58 }
  59
  60 static int is_efer_nx(void)
  61 {
  62         unsigned long long efer = 0;
  63
  64         rdmsrl_safe(MSR_EFER, &efer);
  65         return efer & EFER_NX;
  66 }
  67
  68 static void cpuid_fix_nx_cap(struct kvm_vcpu *vcpu)
  69 {
  70         int i;
  71         struct kvm_cpuid_entry2 *e, *entry;
  72
  73         entry = NULL;
  74         for (i = 0; i < vcpu->arch.cpuid_nent; ++i) {
  75                 e = &vcpu->arch.cpuid_entries[i];
  76                 if (e->function == 0x80000001) {
  77                         entry = e;
  78                         break;
  79                 }
  80         }
  81         if (entry && (entry->edx & (1 << 20)) && !is_efer_nx()) {
  82                 entry->edx &= ~(1 << 20);
  83                 printk(KERN_INFO "kvm: guest NX capability removed\n");
  84         }
  85 }
  86
  87 /* when an old userspace process fills a new kernel module */
  88 int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
  89                              struct kvm_cpuid *cpuid,
  90                              struct kvm_cpuid_entry __user *entries)
  91 {
  92         int r, i;
  93         struct kvm_cpuid_entry *cpuid_entries;
  94
  95         r = -E2BIG;
  96         if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
  97                 goto out;
  98         r = -ENOMEM;
  99         cpuid_entries = vmalloc(sizeof(struct kvm_cpuid_entry) * cpuid->nent);
 100         if (!cpuid_entries)
 101                 goto out;
 102         r = -EFAULT;
 103         if (copy_from_user(cpuid_entries, entries,
 104                            cpuid->nent * sizeof(struct kvm_cpuid_entry)))
 105                 goto out_free;
 106         for (i = 0; i < cpuid->nent; i++) {
 107                 vcpu->arch.cpuid_entries[i].function = cpuid_entries[i].function;
 108                 vcpu->arch.cpuid_entries[i].eax = cpuid_entries[i].eax;
 109                 vcpu->arch.cpuid_entries[i].ebx = cpuid_entries[i].ebx;
 110                 vcpu->arch.cpuid_entries[i].ecx = cpuid_entries[i].ecx;
 111                 vcpu->arch.cpuid_entries[i].edx = cpuid_entries[i].edx;
 112                 vcpu->arch.cpuid_entries[i].index = 0;
 113                 vcpu->arch.cpuid_entries[i].flags = 0;
 114                 vcpu->arch.cpuid_entries[i].padding[0] = 0;
 115                 vcpu->arch.cpuid_entries[i].padding[1] = 0;
 116                 vcpu->arch.cpuid_entries[i].padding[2] = 0;
 117         }
 118         vcpu->arch.cpuid_nent = cpuid->nent;
 119         cpuid_fix_nx_cap(vcpu);
 120         r = 0;
 121         kvm_apic_set_version(vcpu);
 122         kvm_x86_ops->cpuid_update(vcpu);
 123         kvm_update_cpuid(vcpu);
 124
 125 out_free:
 126         vfree(cpuid_entries);
 127 out:
 128         return r;
 129 }
 130
 131 int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
 132                               struct kvm_cpuid2 *cpuid,
 133                               struct kvm_cpuid_entry2 __user *entries)
 134 {
 135         int r;
 136
 137         r = -E2BIG;
 138         if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
 139                 goto out;
 140         r = -EFAULT;
 141         if (copy_from_user(&vcpu->arch.cpuid_entries, entries,
 142                            cpuid->nent * sizeof(struct kvm_cpuid_entry2)))
 143                 goto out;
 144         vcpu->arch.cpuid_nent = cpuid->nent;
 145         kvm_apic_set_version(vcpu);
 146         kvm_x86_ops->cpuid_update(vcpu);
 147         kvm_update_cpuid(vcpu);
 148         return 0;
 149
 150 out:
 151         return r;
 152 }
 153
 154 int kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu *vcpu,
 155                               struct kvm_cpuid2 *cpuid,
 156                               struct kvm_cpuid_entry2 __user *entries)
 157 {
 158         int r;
 159
 160         r = -E2BIG;
 161         if (cpuid->nent < vcpu->arch.cpuid_nent)
 162                 goto out;
 163         r = -EFAULT;
 164         if (copy_to_user(entries, &vcpu->arch.cpuid_entries,
 165                          vcpu->arch.cpuid_nent * sizeof(struct kvm_cpuid_entry2)))
 166                 goto out;
 167         return 0;
 168
 169 out:
 170         cpuid->nent = vcpu->arch.cpuid_nent;
 171         return r;
 172 }
 173
 174 static void cpuid_mask(u32 *word, int wordnum)
 175 {
 176         *word &= boot_cpu_data.x86_capability[wordnum];
 177 }
 178
 179 static void do_cpuid_1_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 180                            u32 index)
 181 {
 182         entry->function = function;
 183         entry->index = index;
 184         cpuid_count(entry->function, entry->index,
 185                     &entry->eax, &entry->ebx, &entry->ecx, &entry->edx);
 186         entry->flags = 0;
 187 }
 188
 189 static bool supported_xcr0_bit(unsigned bit)
 190 {
 191         u64 mask = ((u64)1 << bit);
 192
 193         return mask & KVM_SUPPORTED_XCR0 & host_xcr0;
 194 }
 195
 196 #define F(x) bit(X86_FEATURE_##x)
 197
 198 static int do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 199                          u32 index, int *nent, int maxnent)
 200 {
 201         int r;
 202         unsigned f_nx = is_efer_nx() ? F(NX) : 0;
 203 #ifdef CONFIG_X86_64
 204         unsigned f_gbpages = (kvm_x86_ops->get_lpage_level() == PT_PDPE_LEVEL)
 205                                 ? F(GBPAGES) : 0;
 206         unsigned f_lm = F(LM);
 207 #else
 208         unsigned f_gbpages = 0;
 209         unsigned f_lm = 0;
 210 #endif
 211         unsigned f_rdtscp = kvm_x86_ops->rdtscp_supported() ? F(RDTSCP) : 0;
 212         unsigned f_invpcid = kvm_x86_ops->invpcid_supported() ? F(INVPCID) : 0;
 213
 214         /* cpuid 1.edx */
 215         const u32 kvm_supported_word0_x86_features =
 216                 F(FPU) | F(VME) | F(DE) | F(PSE) |
 217                 F(TSC) | F(MSR) | F(PAE) | F(MCE) |
 218                 F(CX8) | F(APIC) | 0 /* Reserved */ | F(SEP) |
 219                 F(MTRR) | F(PGE) | F(MCA) | F(CMOV) |
 220                 F(PAT) | F(PSE36) | 0 /* PSN */ | F(CLFLSH) |
 221                 0 /* Reserved, DS, ACPI */ | F(MMX) |
 222                 F(FXSR) | F(XMM) | F(XMM2) | F(SELFSNOOP) |
 223                 0 /* HTT, TM, Reserved, PBE */;
 224         /* cpuid 0x80000001.edx */
 225         const u32 kvm_supported_word1_x86_features =
 226                 F(FPU) | F(VME) | F(DE) | F(PSE) |
 227                 F(TSC) | F(MSR) | F(PAE) | F(MCE) |
 228                 F(CX8) | F(APIC) | 0 /* Reserved */ | F(SYSCALL) |
 229                 F(MTRR) | F(PGE) | F(MCA) | F(CMOV) |
 230                 F(PAT) | F(PSE36) | 0 /* Reserved */ |
 231                 f_nx | 0 /* Reserved */ | F(MMXEXT) | F(MMX) |
 232                 F(FXSR) | F(FXSR_OPT) | f_gbpages | f_rdtscp |
 233                 0 /* Reserved */ | f_lm | F(3DNOWEXT) | F(3DNOW);
 234         /* cpuid 1.ecx */
 235         const u32 kvm_supported_word4_x86_features =
 236                 F(XMM3) | F(PCLMULQDQ) | 0 /* DTES64, MONITOR */ |
 237                 0 /* DS-CPL, VMX, SMX, EST */ |
 238                 0 /* TM2 */ | F(SSSE3) | 0 /* CNXT-ID */ | 0 /* Reserved */ |
 239                 F(FMA) | F(CX16) | 0 /* xTPR Update, PDCM */ |
 240                 F(PCID) | 0 /* Reserved, DCA */ | F(XMM4_1) |
 241                 F(XMM4_2) | F(X2APIC) | F(MOVBE) | F(POPCNT) |
 242                 0 /* Reserved*/ | F(AES) | F(XSAVE) | 0 /* OSXSAVE */ | F(AVX) |
 243                 F(F16C) | F(RDRAND);
 244         /* cpuid 0x80000001.ecx */
 245         const u32 kvm_supported_word6_x86_features =
 246                 F(LAHF_LM) | F(CMP_LEGACY) | 0 /*SVM*/ | 0 /* ExtApicSpace */ |
 247                 F(CR8_LEGACY) | F(ABM) | F(SSE4A) | F(MISALIGNSSE) |
 248                 F(3DNOWPREFETCH) | F(OSVW) | 0 /* IBS */ | F(XOP) |
 249                 0 /* SKINIT, WDT, LWP */ | F(FMA4) | F(TBM);
 250
 251         /* cpuid 0xC0000001.edx */
 252         const u32 kvm_supported_word5_x86_features =
 253                 F(XSTORE) | F(XSTORE_EN) | F(XCRYPT) | F(XCRYPT_EN) |
 254                 F(ACE2) | F(ACE2_EN) | F(PHE) | F(PHE_EN) |
 255                 F(PMM) | F(PMM_EN);
 256
 257         /* cpuid 7.0.ebx */
 258         const u32 kvm_supported_word9_x86_features =
 259                 F(FSGSBASE) | F(BMI1) | F(HLE) | F(AVX2) | F(SMEP) |
 260                 F(BMI2) | F(ERMS) | f_invpcid | F(RTM);
 261
 262         /* all calls to cpuid_count() should be made on the same cpu */
 263         get_cpu();
 264
 265         r = -E2BIG;
 266
 267         if (*nent >= maxnent)
 268                 goto out;
 269
 270         do_cpuid_1_ent(entry, function, index);
 271         ++*nent;
 272
 273         switch (function) {
 274         case 0:
 275                 entry->eax = min(entry->eax, (u32)0xd);
 276                 break;
 277         case 1:
 278                 entry->edx &= kvm_supported_word0_x86_features;
 279                 cpuid_mask(&entry->edx, 0);
 280                 entry->ecx &= kvm_supported_word4_x86_features;
 281                 cpuid_mask(&entry->ecx, 4);
 282                 /* we support x2apic emulation even if host does not support
 283                  * it since we emulate x2apic in software */
 284                 entry->ecx |= F(X2APIC);
 285                 break;
 286         /* function 2 entries are STATEFUL. That is, repeated cpuid commands
 287          * may return different values. This forces us to get_cpu() before
 288          * issuing the first command, and also to emulate this annoying behavior
 289          * in kvm_emulate_cpuid() using KVM_CPUID_FLAG_STATE_READ_NEXT */
 290         case 2: {
 291                 int t, times = entry->eax & 0xff;
 292
 293                 entry->flags |= KVM_CPUID_FLAG_STATEFUL_FUNC;
 294                 entry->flags |= KVM_CPUID_FLAG_STATE_READ_NEXT;
 295                 for (t = 1; t < times; ++t) {
 296                         if (*nent >= maxnent)
 297                                 goto out;
 298
 299                         do_cpuid_1_ent(&entry[t], function, 0);
 300                         entry[t].flags |= KVM_CPUID_FLAG_STATEFUL_FUNC;
 301                         ++*nent;
 302                 }
 303                 break;
 304         }
 305         /* function 4 has additional index. */
 306         case 4: {
 307                 int i, cache_type;
 308
 309                 entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
 310                 /* read more entries until cache_type is zero */
 311                 for (i = 1; ; ++i) {
 312                         if (*nent >= maxnent)
 313                                 goto out;
 314
 315                         cache_type = entry[i - 1].eax & 0x1f;
 316                         if (!cache_type)
 317                                 break;
 318                         do_cpuid_1_ent(&entry[i], function, i);
 319                         entry[i].flags |=
 320                                KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
 321                         ++*nent;
 322                 }
 323                 break;
 324         }
 325         case 7: {
 326                 entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
 327                 /* Mask ebx against host capability word 9 */
 328                 if (index == 0) {
 329                         entry->ebx &= kvm_supported_word9_x86_features;
 330                         cpuid_mask(&entry->ebx, 9);
 331                         // TSC_ADJUST is emulated
 332                         entry->ebx |= F(TSC_ADJUST);
 333                 } else
 334                         entry->ebx = 0;
 335                 entry->eax = 0;
 336                 entry->ecx = 0;
 337                 entry->edx = 0;
 338                 break;
 339         }
 340         case 9:
 341                 break;
 342         case 0xa: { /* Architectural Performance Monitoring */
 343                 struct x86_pmu_capability cap;
 344                 union cpuid10_eax eax;
 345                 union cpuid10_edx edx;
 346
 347                 perf_get_x86_pmu_capability(&cap);
 348
 349                 /*
 350                  * Only support guest architectural pmu on a host
 351                  * with architectural pmu.
 352                  */
 353                 if (!cap.version)
 354                         memset(&cap, 0, sizeof(cap));
 355
 356                 eax.split.version_id = min(cap.version, 2);
 357                 eax.split.num_counters = cap.num_counters_gp;
 358                 eax.split.bit_width = cap.bit_width_gp;
 359                 eax.split.mask_length = cap.events_mask_len;
 360
 361                 edx.split.num_counters_fixed = cap.num_counters_fixed;
 362                 edx.split.bit_width_fixed = cap.bit_width_fixed;
 363                 edx.split.reserved = 0;
 364
 365                 entry->eax = eax.full;
 366                 entry->ebx = cap.events_mask;
 367                 entry->ecx = 0;
 368                 entry->edx = edx.full;
 369                 break;
 370         }
 371         /* function 0xb has additional index. */
 372         case 0xb: {
 373                 int i, level_type;
 374
 375                 entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
 376                 /* read more entries until level_type is zero */
 377                 for (i = 1; ; ++i) {
 378                         if (*nent >= maxnent)
 379                                 goto out;
 380
 381                         level_type = entry[i - 1].ecx & 0xff00;
 382                         if (!level_type)
 383                                 break;
 384                         do_cpuid_1_ent(&entry[i], function, i);
 385                         entry[i].flags |=
 386                                KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
 387                         ++*nent;
 388                 }
 389                 break;
 390         }
 391         case 0xd: {
 392                 int idx, i;
 393
 394                 entry->eax &= host_xcr0 & KVM_SUPPORTED_XCR0;
 395                 entry->edx &= (host_xcr0 & KVM_SUPPORTED_XCR0) >> 32;
 396                 entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
 397                 for (idx = 1, i = 1; idx < 64; ++idx) {
 398                         if (*nent >= maxnent)
 399                                 goto out;
 400
 401                         do_cpuid_1_ent(&entry[i], function, idx);
 402                         if (entry[i].eax == 0 || !supported_xcr0_bit(idx))
 403                                 continue;
 404                         entry[i].flags |=
 405                                KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
 406                         ++*nent;
 407                         ++i;
 408                 }
 409                 break;
 410         }
 411         case KVM_CPUID_SIGNATURE: {
 412                 static const char signature[12] = "KVMKVMKVM\0\0";
 413                 const u32 *sigptr = (const u32 *)signature;
 414                 entry->eax = KVM_CPUID_FEATURES;
 415                 entry->ebx = sigptr[0];
 416                 entry->ecx = sigptr[1];
 417                 entry->edx = sigptr[2];
 418                 break;
 419         }
 420         case KVM_CPUID_FEATURES:
 421                 entry->eax = (1 << KVM_FEATURE_CLOCKSOURCE) |
 422                              (1 << KVM_FEATURE_NOP_IO_DELAY) |
 423                              (1 << KVM_FEATURE_CLOCKSOURCE2) |
 424                              (1 << KVM_FEATURE_ASYNC_PF) |
 425                              (1 << KVM_FEATURE_PV_EOI) |
 426                              (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) |
 427                              (1 << KVM_FEATURE_PV_UNHALT);
 428
 429                 if (sched_info_on())
 430                         entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);
 431
 432                 entry->ebx = 0;
 433                 entry->ecx = 0;
 434                 entry->edx = 0;
 435                 break;
 436         case 0x80000000:
 437                 entry->eax = min(entry->eax, 0x8000001a);
 438                 break;
 439         case 0x80000001:
 440                 entry->edx &= kvm_supported_word1_x86_features;
 441                 cpuid_mask(&entry->edx, 1);
 442                 entry->ecx &= kvm_supported_word6_x86_features;
 443                 cpuid_mask(&entry->ecx, 6);
 444                 break;
 445         case 0x80000008: {
 446                 unsigned g_phys_as = (entry->eax >> 16) & 0xff;
 447                 unsigned virt_as = max((entry->eax >> 8) & 0xff, 48U);
 448                 unsigned phys_as = entry->eax & 0xff;
 449
 450                 if (!g_phys_as)
 451                         g_phys_as = phys_as;
 452                 entry->eax = g_phys_as | (virt_as << 8);
 453                 entry->ebx = entry->edx = 0;
 454                 break;
 455         }
 456         case 0x80000019:
 457                 entry->ecx = entry->edx = 0;
 458                 break;
 459         case 0x8000001a:
 460                 break;
 461         case 0x8000001d:
 462                 break;
 463         /*Add support for Centaur's CPUID instruction*/
 464         case 0xC0000000:
 465                 /*Just support up to 0xC0000004 now*/
 466                 entry->eax = min(entry->eax, 0xC0000004);
 467                 break;
 468         case 0xC0000001:
 469                 entry->edx &= kvm_supported_word5_x86_features;
 470                 cpuid_mask(&entry->edx, 5);
 471                 break;
 472         case 3: /* Processor serial number */
 473         case 5: /* MONITOR/MWAIT */
 474         case 6: /* Thermal management */
 475         case 0x80000007: /* Advanced power management */
 476         case 0xC0000002:
 477         case 0xC0000003:
 478         case 0xC0000004:
 479         default:
 480                 entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
 481                 break;
 482         }
 483
 484         kvm_x86_ops->set_supported_cpuid(function, entry);
 485
 486         r = 0;
 487
 488 out:
 489         put_cpu();
 490
 491         return r;
 492 }
 493
 494 #undef F
 495
 496 struct kvm_cpuid_param {
 497         u32 func;
 498         u32 idx;
 499         bool has_leaf_count;
 500         bool (*qualifier)(const struct kvm_cpuid_param *param);
 501 };
 502
 503 static bool is_centaur_cpu(const struct kvm_cpuid_param *param)
 504 {
 505         return boot_cpu_data.x86_vendor == X86_VENDOR_CENTAUR;
 506 }
 507
 508 int kvm_dev_ioctl_get_supported_cpuid(struct kvm_cpuid2 *cpuid,
 509                                       struct kvm_cpuid_entry2 __user *entries)
 510 {
 511         struct kvm_cpuid_entry2 *cpuid_entries;
 512         int limit, nent = 0, r = -E2BIG, i;
 513         u32 func;
 514         static const struct kvm_cpuid_param param[] = {
 515                 { .func = 0, .has_leaf_count = true },
 516                 { .func = 0x80000000, .has_leaf_count = true },
 517                 { .func = 0xC0000000, .qualifier = is_centaur_cpu, .has_leaf_count = true },
 518                 { .func = KVM_CPUID_SIGNATURE },
 519                 { .func = KVM_CPUID_FEATURES },
 520         };
 521
 522         if (cpuid->nent < 1)
 523                 goto out;
 524         if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
 525                 cpuid->nent = KVM_MAX_CPUID_ENTRIES;
 526         r = -ENOMEM;
 527         cpuid_entries = vmalloc(sizeof(struct kvm_cpuid_entry2) * cpuid->nent);
 528         if (!cpuid_entries)
 529                 goto out;
 530
 531         r = 0;
 532         for (i = 0; i < ARRAY_SIZE(param); i++) {
 533                 const struct kvm_cpuid_param *ent = &param[i];
 534
 535                 if (ent->qualifier && !ent->qualifier(ent))
 536                         continue;
 537
 538                 r = do_cpuid_ent(&cpuid_entries[nent], ent->func, ent->idx,
 539                                 &nent, cpuid->nent);
 540
 541                 if (r)
 542                         goto out_free;
 543
 544                 if (!ent->has_leaf_count)
 545                         continue;
 546
 547                 limit = cpuid_entries[nent - 1].eax;
 548                 for (func = ent->func + 1; func <= limit && nent < cpuid->nent && r == 0; ++func)
 549                         r = do_cpuid_ent(&cpuid_entries[nent], func, ent->idx,
 550                                      &nent, cpuid->nent);
 551
 552                 if (r)
 553                         goto out_free;
 554         }
 555
 556         r = -EFAULT;
 557         if (copy_to_user(entries, cpuid_entries,
 558                          nent * sizeof(struct kvm_cpuid_entry2)))
 559                 goto out_free;
 560         cpuid->nent = nent;
 561         r = 0;
 562
 563 out_free:
 564         vfree(cpuid_entries);
 565 out:
 566         return r;
 567 }
 568
 569 static int move_to_next_stateful_cpuid_entry(struct kvm_vcpu *vcpu, int i)
 570 {
 571         struct kvm_cpuid_entry2 *e = &vcpu->arch.cpuid_entries[i];
 572         int j, nent = vcpu->arch.cpuid_nent;
 573
 574         e->flags &= ~KVM_CPUID_FLAG_STATE_READ_NEXT;
 575         /* when no next entry is found, the current entry[i] is reselected */
 576         for (j = i + 1; ; j = (j + 1) % nent) {
 577                 struct kvm_cpuid_entry2 *ej = &vcpu->arch.cpuid_entries[j];
 578                 if (ej->function == e->function) {
 579                         ej->flags |= KVM_CPUID_FLAG_STATE_READ_NEXT;
 580                         return j;
 581                 }
 582         }
 583         return 0; /* silence gcc, even though control never reaches here */
 584 }
 585
 586 /* find an entry with matching function, matching index (if needed), and that
 587  * should be read next (if it's stateful) */
 588 static int is_matching_cpuid_entry(struct kvm_cpuid_entry2 *e,
 589         u32 function, u32 index)
 590 {
 591         if (e->function != function)
 592                 return 0;
 593         if ((e->flags & KVM_CPUID_FLAG_SIGNIFCANT_INDEX) && e->index != index)
 594                 return 0;
 595         if ((e->flags & KVM_CPUID_FLAG_STATEFUL_FUNC) &&
 596             !(e->flags & KVM_CPUID_FLAG_STATE_READ_NEXT))
 597                 return 0;
 598         return 1;
 599 }
 600
 601 struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
 602                                               u32 function, u32 index)
 603 {
 604         int i;
 605         struct kvm_cpuid_entry2 *best = NULL;
 606
 607         for (i = 0; i < vcpu->arch.cpuid_nent; ++i) {
 608                 struct kvm_cpuid_entry2 *e;
 609
 610                 e = &vcpu->arch.cpuid_entries[i];
 611                 if (is_matching_cpuid_entry(e, function, index)) {
 612                         if (e->flags & KVM_CPUID_FLAG_STATEFUL_FUNC)
 613                                 move_to_next_stateful_cpuid_entry(vcpu, i);
 614                         best = e;
 615                         break;
 616                 }
 617         }
 618         return best;
 619 }
 620 EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry);
 621
 622 int cpuid_maxphyaddr(struct kvm_vcpu *vcpu)
 623 {
 624         struct kvm_cpuid_entry2 *best;
 625
 626         best = kvm_find_cpuid_entry(vcpu, 0x80000000, 0);
 627         if (!best || best->eax < 0x80000008)
 628                 goto not_found;
 629         best = kvm_find_cpuid_entry(vcpu, 0x80000008, 0);
 630         if (best)
 631                 return best->eax & 0xff;
 632 not_found:
 633         return 36;
 634 }
 635
 636 /*
 637  * If no match is found, check whether we exceed the vCPU's limit
 638  * and return the content of the highest valid _standard_ leaf instead.
 639  * This is to satisfy the CPUID specification.
 640  */
 641 static struct kvm_cpuid_entry2* check_cpuid_limit(struct kvm_vcpu *vcpu,
 642                                                   u32 function, u32 index)
 643 {
 644         struct kvm_cpuid_entry2 *maxlevel;
 645
 646         maxlevel = kvm_find_cpuid_entry(vcpu, function & 0x80000000, 0);
 647         if (!maxlevel || maxlevel->eax >= function)
 648                 return NULL;
 649         if (function & 0x80000000) {
 650                 maxlevel = kvm_find_cpuid_entry(vcpu, 0, 0);
 651                 if (!maxlevel)
 652                         return NULL;
 653         }
 654         return kvm_find_cpuid_entry(vcpu, maxlevel->eax, index);
 655 }
 656
 657 void kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx, u32 *ecx, u32 *edx)
 658 {
 659         u32 function = *eax, index = *ecx;
 660         struct kvm_cpuid_entry2 *best;
 661
 662         best = kvm_find_cpuid_entry(vcpu, function, index);
 663
 664         if (!best)
 665                 best = check_cpuid_limit(vcpu, function, index);
 666
 667         if (best) {
 668                 *eax = best->eax;
 669                 *ebx = best->ebx;
 670                 *ecx = best->ecx;
 671                 *edx = best->edx;
 672         } else
 673                 *eax = *ebx = *ecx = *edx = 0;
 674 }
 675 EXPORT_SYMBOL_GPL(kvm_cpuid);
 676
 677 void kvm_emulate_cpuid(struct kvm_vcpu *vcpu)
 678 {
 679         u32 function, eax, ebx, ecx, edx;
 680
 681         function = eax = kvm_register_read(vcpu, VCPU_REGS_RAX);
 682         ecx = kvm_register_read(vcpu, VCPU_REGS_RCX);
 683         kvm_cpuid(vcpu, &eax, &ebx, &ecx, &edx);
 684         kvm_register_write(vcpu, VCPU_REGS_RAX, eax);
 685         kvm_register_write(vcpu, VCPU_REGS_RBX, ebx);
 686         kvm_register_write(vcpu, VCPU_REGS_RCX, ecx);
 687         kvm_register_write(vcpu, VCPU_REGS_RDX, edx);
 688         kvm_x86_ops->skip_emulated_instruction(vcpu);
 689         trace_kvm_cpuid(function, eax, ebx, ecx, edx);
 690 }
 691 EXPORT_SYMBOL_GPL(kvm_emulate_cpuid);