2 * Kernel-based Virtual Machine driver for Linux
3 * cpuid support routines
5 * derived from arch/x86/kvm/x86.c
7 * Copyright 2011 Red Hat, Inc. and/or its affiliates.
8 * Copyright IBM Corporation, 2008
10 * This work is licensed under the terms of the GNU GPL, version 2. See
11 * the COPYING file in the top-level directory.
15 #include <linux/kvm_host.h>
16 #include <linux/module.h>
17 #include <linux/vmalloc.h>
18 #include <linux/uaccess.h>
20 #include <asm/xsave.h>
26 static u32 xstate_required_size(u64 xstate_bv, bool compacted)
29 u32 ret = XSAVE_HDR_SIZE + XSAVE_HDR_OFFSET;
31 xstate_bv &= XSTATE_EXTEND_MASK;
33 if (xstate_bv & 0x1) {
34 u32 eax, ebx, ecx, edx, offset;
35 cpuid_count(0xD, feature_bit, &eax, &ebx, &ecx, &edx);
36 offset = compacted ? ret : ebx;
37 ret = max(ret, offset + eax);
47 u64 kvm_supported_xcr0(void)
49 u64 xcr0 = KVM_SUPPORTED_XCR0 & host_xcr0;
51 if (!kvm_x86_ops->mpx_supported())
52 xcr0 &= ~(XSTATE_BNDREGS | XSTATE_BNDCSR);
57 #define F(x) bit(X86_FEATURE_##x)
59 int kvm_update_cpuid(struct kvm_vcpu *vcpu)
61 struct kvm_cpuid_entry2 *best;
62 struct kvm_lapic *apic = vcpu->arch.apic;
64 best = kvm_find_cpuid_entry(vcpu, 1, 0);
68 /* Update OSXSAVE bit */
69 if (cpu_has_xsave && best->function == 0x1) {
70 best->ecx &= ~F(OSXSAVE);
71 if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE))
72 best->ecx |= F(OSXSAVE);
76 if (best->ecx & F(TSC_DEADLINE_TIMER))
77 apic->lapic_timer.timer_mode_mask = 3 << 17;
79 apic->lapic_timer.timer_mode_mask = 1 << 17;
82 best = kvm_find_cpuid_entry(vcpu, 0xD, 0);
84 vcpu->arch.guest_supported_xcr0 = 0;
85 vcpu->arch.guest_xstate_size = XSAVE_HDR_SIZE + XSAVE_HDR_OFFSET;
87 vcpu->arch.guest_supported_xcr0 =
88 (best->eax | ((u64)best->edx << 32)) &
90 vcpu->arch.guest_xstate_size = best->ebx =
91 xstate_required_size(vcpu->arch.xcr0, false);
94 best = kvm_find_cpuid_entry(vcpu, 0xD, 1);
95 if (best && (best->eax & (F(XSAVES) | F(XSAVEC))))
96 best->ebx = xstate_required_size(vcpu->arch.xcr0, true);
99 * The existing code assumes virtual address is 48-bit in the canonical
100 * address checks; exit if it is ever changed.
102 best = kvm_find_cpuid_entry(vcpu, 0x80000008, 0);
103 if (best && ((best->eax & 0xff00) >> 8) != 48 &&
104 ((best->eax & 0xff00) >> 8) != 0)
107 /* Update physical-address width */
108 vcpu->arch.maxphyaddr = cpuid_query_maxphyaddr(vcpu);
110 kvm_pmu_cpuid_update(vcpu);
114 static int is_efer_nx(void)
116 unsigned long long efer = 0;
118 rdmsrl_safe(MSR_EFER, &efer);
119 return efer & EFER_NX;
122 static void cpuid_fix_nx_cap(struct kvm_vcpu *vcpu)
125 struct kvm_cpuid_entry2 *e, *entry;
128 for (i = 0; i < vcpu->arch.cpuid_nent; ++i) {
129 e = &vcpu->arch.cpuid_entries[i];
130 if (e->function == 0x80000001) {
135 if (entry && (entry->edx & F(NX)) && !is_efer_nx()) {
136 entry->edx &= ~F(NX);
137 printk(KERN_INFO "kvm: guest NX capability removed\n");
141 int cpuid_query_maxphyaddr(struct kvm_vcpu *vcpu)
143 struct kvm_cpuid_entry2 *best;
145 best = kvm_find_cpuid_entry(vcpu, 0x80000000, 0);
146 if (!best || best->eax < 0x80000008)
148 best = kvm_find_cpuid_entry(vcpu, 0x80000008, 0);
150 return best->eax & 0xff;
154 EXPORT_SYMBOL_GPL(cpuid_query_maxphyaddr);
156 /* when an old userspace process fills a new kernel module */
157 int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
158 struct kvm_cpuid *cpuid,
159 struct kvm_cpuid_entry __user *entries)
162 struct kvm_cpuid_entry *cpuid_entries;
165 if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
168 cpuid_entries = vmalloc(sizeof(struct kvm_cpuid_entry) * cpuid->nent);
172 if (copy_from_user(cpuid_entries, entries,
173 cpuid->nent * sizeof(struct kvm_cpuid_entry)))
175 for (i = 0; i < cpuid->nent; i++) {
176 vcpu->arch.cpuid_entries[i].function = cpuid_entries[i].function;
177 vcpu->arch.cpuid_entries[i].eax = cpuid_entries[i].eax;
178 vcpu->arch.cpuid_entries[i].ebx = cpuid_entries[i].ebx;
179 vcpu->arch.cpuid_entries[i].ecx = cpuid_entries[i].ecx;
180 vcpu->arch.cpuid_entries[i].edx = cpuid_entries[i].edx;
181 vcpu->arch.cpuid_entries[i].index = 0;
182 vcpu->arch.cpuid_entries[i].flags = 0;
183 vcpu->arch.cpuid_entries[i].padding[0] = 0;
184 vcpu->arch.cpuid_entries[i].padding[1] = 0;
185 vcpu->arch.cpuid_entries[i].padding[2] = 0;
187 vcpu->arch.cpuid_nent = cpuid->nent;
188 cpuid_fix_nx_cap(vcpu);
189 kvm_apic_set_version(vcpu);
190 kvm_x86_ops->cpuid_update(vcpu);
191 r = kvm_update_cpuid(vcpu);
194 vfree(cpuid_entries);
199 int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
200 struct kvm_cpuid2 *cpuid,
201 struct kvm_cpuid_entry2 __user *entries)
206 if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
209 if (copy_from_user(&vcpu->arch.cpuid_entries, entries,
210 cpuid->nent * sizeof(struct kvm_cpuid_entry2)))
212 vcpu->arch.cpuid_nent = cpuid->nent;
213 kvm_apic_set_version(vcpu);
214 kvm_x86_ops->cpuid_update(vcpu);
215 r = kvm_update_cpuid(vcpu);
220 int kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu *vcpu,
221 struct kvm_cpuid2 *cpuid,
222 struct kvm_cpuid_entry2 __user *entries)
227 if (cpuid->nent < vcpu->arch.cpuid_nent)
230 if (copy_to_user(entries, &vcpu->arch.cpuid_entries,
231 vcpu->arch.cpuid_nent * sizeof(struct kvm_cpuid_entry2)))
236 cpuid->nent = vcpu->arch.cpuid_nent;
240 static void cpuid_mask(u32 *word, int wordnum)
242 *word &= boot_cpu_data.x86_capability[wordnum];
245 static void do_cpuid_1_ent(struct kvm_cpuid_entry2 *entry, u32 function,
248 entry->function = function;
249 entry->index = index;
250 cpuid_count(entry->function, entry->index,
251 &entry->eax, &entry->ebx, &entry->ecx, &entry->edx);
255 static int __do_cpuid_ent_emulated(struct kvm_cpuid_entry2 *entry,
256 u32 func, u32 index, int *nent, int maxnent)
260 entry->eax = 1; /* only one leaf currently */
264 entry->ecx = F(MOVBE);
271 entry->function = func;
272 entry->index = index;
277 static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
278 u32 index, int *nent, int maxnent)
281 unsigned f_nx = is_efer_nx() ? F(NX) : 0;
283 unsigned f_gbpages = (kvm_x86_ops->get_lpage_level() == PT_PDPE_LEVEL)
285 unsigned f_lm = F(LM);
287 unsigned f_gbpages = 0;
290 unsigned f_rdtscp = kvm_x86_ops->rdtscp_supported() ? F(RDTSCP) : 0;
291 unsigned f_invpcid = kvm_x86_ops->invpcid_supported() ? F(INVPCID) : 0;
292 unsigned f_mpx = kvm_x86_ops->mpx_supported() ? F(MPX) : 0;
293 unsigned f_xsaves = kvm_x86_ops->xsaves_supported() ? F(XSAVES) : 0;
296 const u32 kvm_supported_word0_x86_features =
297 F(FPU) | F(VME) | F(DE) | F(PSE) |
298 F(TSC) | F(MSR) | F(PAE) | F(MCE) |
299 F(CX8) | F(APIC) | 0 /* Reserved */ | F(SEP) |
300 F(MTRR) | F(PGE) | F(MCA) | F(CMOV) |
301 F(PAT) | F(PSE36) | 0 /* PSN */ | F(CLFLUSH) |
302 0 /* Reserved, DS, ACPI */ | F(MMX) |
303 F(FXSR) | F(XMM) | F(XMM2) | F(SELFSNOOP) |
304 0 /* HTT, TM, Reserved, PBE */;
305 /* cpuid 0x80000001.edx */
306 const u32 kvm_supported_word1_x86_features =
307 F(FPU) | F(VME) | F(DE) | F(PSE) |
308 F(TSC) | F(MSR) | F(PAE) | F(MCE) |
309 F(CX8) | F(APIC) | 0 /* Reserved */ | F(SYSCALL) |
310 F(MTRR) | F(PGE) | F(MCA) | F(CMOV) |
311 F(PAT) | F(PSE36) | 0 /* Reserved */ |
312 f_nx | 0 /* Reserved */ | F(MMXEXT) | F(MMX) |
313 F(FXSR) | F(FXSR_OPT) | f_gbpages | f_rdtscp |
314 0 /* Reserved */ | f_lm | F(3DNOWEXT) | F(3DNOW);
316 const u32 kvm_supported_word4_x86_features =
317 /* NOTE: MONITOR (and MWAIT) are emulated as NOP,
318 * but *not* advertised to guests via CPUID ! */
319 F(XMM3) | F(PCLMULQDQ) | 0 /* DTES64, MONITOR */ |
320 0 /* DS-CPL, VMX, SMX, EST */ |
321 0 /* TM2 */ | F(SSSE3) | 0 /* CNXT-ID */ | 0 /* Reserved */ |
322 F(FMA) | F(CX16) | 0 /* xTPR Update, PDCM */ |
323 F(PCID) | 0 /* Reserved, DCA */ | F(XMM4_1) |
324 F(XMM4_2) | F(X2APIC) | F(MOVBE) | F(POPCNT) |
325 0 /* Reserved*/ | F(AES) | F(XSAVE) | 0 /* OSXSAVE */ | F(AVX) |
327 /* cpuid 0x80000001.ecx */
328 const u32 kvm_supported_word6_x86_features =
329 F(LAHF_LM) | F(CMP_LEGACY) | 0 /*SVM*/ | 0 /* ExtApicSpace */ |
330 F(CR8_LEGACY) | F(ABM) | F(SSE4A) | F(MISALIGNSSE) |
331 F(3DNOWPREFETCH) | F(OSVW) | 0 /* IBS */ | F(XOP) |
332 0 /* SKINIT, WDT, LWP */ | F(FMA4) | F(TBM);
334 /* cpuid 0xC0000001.edx */
335 const u32 kvm_supported_word5_x86_features =
336 F(XSTORE) | F(XSTORE_EN) | F(XCRYPT) | F(XCRYPT_EN) |
337 F(ACE2) | F(ACE2_EN) | F(PHE) | F(PHE_EN) |
341 const u32 kvm_supported_word9_x86_features =
342 F(FSGSBASE) | F(BMI1) | F(HLE) | F(AVX2) | F(SMEP) |
343 F(BMI2) | F(ERMS) | f_invpcid | F(RTM) | f_mpx | F(RDSEED) |
344 F(ADX) | F(SMAP) | F(AVX512F) | F(AVX512PF) | F(AVX512ER) |
347 /* cpuid 0xD.1.eax */
348 const u32 kvm_supported_word10_x86_features =
349 F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1) | f_xsaves;
351 /* all calls to cpuid_count() should be made on the same cpu */
356 if (*nent >= maxnent)
359 do_cpuid_1_ent(entry, function, index);
364 entry->eax = min(entry->eax, (u32)0xd);
367 entry->edx &= kvm_supported_word0_x86_features;
368 cpuid_mask(&entry->edx, 0);
369 entry->ecx &= kvm_supported_word4_x86_features;
370 cpuid_mask(&entry->ecx, 4);
371 /* we support x2apic emulation even if host does not support
372 * it since we emulate x2apic in software */
373 entry->ecx |= F(X2APIC);
375 /* function 2 entries are STATEFUL. That is, repeated cpuid commands
376 * may return different values. This forces us to get_cpu() before
377 * issuing the first command, and also to emulate this annoying behavior
378 * in kvm_emulate_cpuid() using KVM_CPUID_FLAG_STATE_READ_NEXT */
380 int t, times = entry->eax & 0xff;
382 entry->flags |= KVM_CPUID_FLAG_STATEFUL_FUNC;
383 entry->flags |= KVM_CPUID_FLAG_STATE_READ_NEXT;
384 for (t = 1; t < times; ++t) {
385 if (*nent >= maxnent)
388 do_cpuid_1_ent(&entry[t], function, 0);
389 entry[t].flags |= KVM_CPUID_FLAG_STATEFUL_FUNC;
394 /* function 4 has additional index. */
398 entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
399 /* read more entries until cache_type is zero */
401 if (*nent >= maxnent)
404 cache_type = entry[i - 1].eax & 0x1f;
407 do_cpuid_1_ent(&entry[i], function, i);
409 KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
415 entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
416 /* Mask ebx against host capability word 9 */
418 entry->ebx &= kvm_supported_word9_x86_features;
419 cpuid_mask(&entry->ebx, 9);
420 // TSC_ADJUST is emulated
421 entry->ebx |= F(TSC_ADJUST);
431 case 0xa: { /* Architectural Performance Monitoring */
432 struct x86_pmu_capability cap;
433 union cpuid10_eax eax;
434 union cpuid10_edx edx;
436 perf_get_x86_pmu_capability(&cap);
439 * Only support guest architectural pmu on a host
440 * with architectural pmu.
443 memset(&cap, 0, sizeof(cap));
445 eax.split.version_id = min(cap.version, 2);
446 eax.split.num_counters = cap.num_counters_gp;
447 eax.split.bit_width = cap.bit_width_gp;
448 eax.split.mask_length = cap.events_mask_len;
450 edx.split.num_counters_fixed = cap.num_counters_fixed;
451 edx.split.bit_width_fixed = cap.bit_width_fixed;
452 edx.split.reserved = 0;
454 entry->eax = eax.full;
455 entry->ebx = cap.events_mask;
457 entry->edx = edx.full;
460 /* function 0xb has additional index. */
464 entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
465 /* read more entries until level_type is zero */
467 if (*nent >= maxnent)
470 level_type = entry[i - 1].ecx & 0xff00;
473 do_cpuid_1_ent(&entry[i], function, i);
475 KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
482 u64 supported = kvm_supported_xcr0();
484 entry->eax &= supported;
485 entry->ebx = xstate_required_size(supported, false);
486 entry->ecx = entry->ebx;
487 entry->edx &= supported >> 32;
488 entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
492 for (idx = 1, i = 1; idx < 64; ++idx) {
493 u64 mask = ((u64)1 << idx);
494 if (*nent >= maxnent)
497 do_cpuid_1_ent(&entry[i], function, idx);
499 entry[i].eax &= kvm_supported_word10_x86_features;
501 if (entry[i].eax & (F(XSAVES)|F(XSAVEC)))
503 xstate_required_size(supported,
506 if (entry[i].eax == 0 || !(supported & mask))
508 if (WARN_ON_ONCE(entry[i].ecx & 1))
514 KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
520 case KVM_CPUID_SIGNATURE: {
521 static const char signature[12] = "KVMKVMKVM\0\0";
522 const u32 *sigptr = (const u32 *)signature;
523 entry->eax = KVM_CPUID_FEATURES;
524 entry->ebx = sigptr[0];
525 entry->ecx = sigptr[1];
526 entry->edx = sigptr[2];
529 case KVM_CPUID_FEATURES:
530 entry->eax = (1 << KVM_FEATURE_CLOCKSOURCE) |
531 (1 << KVM_FEATURE_NOP_IO_DELAY) |
532 (1 << KVM_FEATURE_CLOCKSOURCE2) |
533 (1 << KVM_FEATURE_ASYNC_PF) |
534 (1 << KVM_FEATURE_PV_EOI) |
535 (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) |
536 (1 << KVM_FEATURE_PV_UNHALT);
539 entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);
546 entry->eax = min(entry->eax, 0x8000001a);
549 entry->edx &= kvm_supported_word1_x86_features;
550 cpuid_mask(&entry->edx, 1);
551 entry->ecx &= kvm_supported_word6_x86_features;
552 cpuid_mask(&entry->ecx, 6);
554 case 0x80000007: /* Advanced power management */
555 /* invariant TSC is CPUID.80000007H:EDX[8] */
556 entry->edx &= (1 << 8);
557 /* mask against host */
558 entry->edx &= boot_cpu_data.x86_power;
559 entry->eax = entry->ebx = entry->ecx = 0;
562 unsigned g_phys_as = (entry->eax >> 16) & 0xff;
563 unsigned virt_as = max((entry->eax >> 8) & 0xff, 48U);
564 unsigned phys_as = entry->eax & 0xff;
568 entry->eax = g_phys_as | (virt_as << 8);
569 entry->ebx = entry->edx = 0;
573 entry->ecx = entry->edx = 0;
579 /*Add support for Centaur's CPUID instruction*/
581 /*Just support up to 0xC0000004 now*/
582 entry->eax = min(entry->eax, 0xC0000004);
585 entry->edx &= kvm_supported_word5_x86_features;
586 cpuid_mask(&entry->edx, 5);
588 case 3: /* Processor serial number */
589 case 5: /* MONITOR/MWAIT */
590 case 6: /* Thermal management */
595 entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
599 kvm_x86_ops->set_supported_cpuid(function, entry);
609 static int do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 func,
610 u32 idx, int *nent, int maxnent, unsigned int type)
612 if (type == KVM_GET_EMULATED_CPUID)
613 return __do_cpuid_ent_emulated(entry, func, idx, nent, maxnent);
615 return __do_cpuid_ent(entry, func, idx, nent, maxnent);
620 struct kvm_cpuid_param {
624 bool (*qualifier)(const struct kvm_cpuid_param *param);
627 static bool is_centaur_cpu(const struct kvm_cpuid_param *param)
629 return boot_cpu_data.x86_vendor == X86_VENDOR_CENTAUR;
632 static bool sanity_check_entries(struct kvm_cpuid_entry2 __user *entries,
633 __u32 num_entries, unsigned int ioctl_type)
638 if (ioctl_type != KVM_GET_EMULATED_CPUID)
642 * We want to make sure that ->padding is being passed clean from
643 * userspace in case we want to use it for something in the future.
645 * Sadly, this wasn't enforced for KVM_GET_SUPPORTED_CPUID and so we
646 * have to give ourselves satisfied only with the emulated side. /me
649 for (i = 0; i < num_entries; i++) {
650 if (copy_from_user(pad, entries[i].padding, sizeof(pad)))
653 if (pad[0] || pad[1] || pad[2])
659 int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid,
660 struct kvm_cpuid_entry2 __user *entries,
663 struct kvm_cpuid_entry2 *cpuid_entries;
664 int limit, nent = 0, r = -E2BIG, i;
666 static const struct kvm_cpuid_param param[] = {
667 { .func = 0, .has_leaf_count = true },
668 { .func = 0x80000000, .has_leaf_count = true },
669 { .func = 0xC0000000, .qualifier = is_centaur_cpu, .has_leaf_count = true },
670 { .func = KVM_CPUID_SIGNATURE },
671 { .func = KVM_CPUID_FEATURES },
676 if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
677 cpuid->nent = KVM_MAX_CPUID_ENTRIES;
679 if (sanity_check_entries(entries, cpuid->nent, type))
683 cpuid_entries = vzalloc(sizeof(struct kvm_cpuid_entry2) * cpuid->nent);
688 for (i = 0; i < ARRAY_SIZE(param); i++) {
689 const struct kvm_cpuid_param *ent = ¶m[i];
691 if (ent->qualifier && !ent->qualifier(ent))
694 r = do_cpuid_ent(&cpuid_entries[nent], ent->func, ent->idx,
695 &nent, cpuid->nent, type);
700 if (!ent->has_leaf_count)
703 limit = cpuid_entries[nent - 1].eax;
704 for (func = ent->func + 1; func <= limit && nent < cpuid->nent && r == 0; ++func)
705 r = do_cpuid_ent(&cpuid_entries[nent], func, ent->idx,
706 &nent, cpuid->nent, type);
713 if (copy_to_user(entries, cpuid_entries,
714 nent * sizeof(struct kvm_cpuid_entry2)))
720 vfree(cpuid_entries);
725 static int move_to_next_stateful_cpuid_entry(struct kvm_vcpu *vcpu, int i)
727 struct kvm_cpuid_entry2 *e = &vcpu->arch.cpuid_entries[i];
728 int j, nent = vcpu->arch.cpuid_nent;
730 e->flags &= ~KVM_CPUID_FLAG_STATE_READ_NEXT;
731 /* when no next entry is found, the current entry[i] is reselected */
732 for (j = i + 1; ; j = (j + 1) % nent) {
733 struct kvm_cpuid_entry2 *ej = &vcpu->arch.cpuid_entries[j];
734 if (ej->function == e->function) {
735 ej->flags |= KVM_CPUID_FLAG_STATE_READ_NEXT;
739 return 0; /* silence gcc, even though control never reaches here */
742 /* find an entry with matching function, matching index (if needed), and that
743 * should be read next (if it's stateful) */
744 static int is_matching_cpuid_entry(struct kvm_cpuid_entry2 *e,
745 u32 function, u32 index)
747 if (e->function != function)
749 if ((e->flags & KVM_CPUID_FLAG_SIGNIFCANT_INDEX) && e->index != index)
751 if ((e->flags & KVM_CPUID_FLAG_STATEFUL_FUNC) &&
752 !(e->flags & KVM_CPUID_FLAG_STATE_READ_NEXT))
757 struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
758 u32 function, u32 index)
761 struct kvm_cpuid_entry2 *best = NULL;
763 for (i = 0; i < vcpu->arch.cpuid_nent; ++i) {
764 struct kvm_cpuid_entry2 *e;
766 e = &vcpu->arch.cpuid_entries[i];
767 if (is_matching_cpuid_entry(e, function, index)) {
768 if (e->flags & KVM_CPUID_FLAG_STATEFUL_FUNC)
769 move_to_next_stateful_cpuid_entry(vcpu, i);
776 EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry);
779 * If no match is found, check whether we exceed the vCPU's limit
780 * and return the content of the highest valid _standard_ leaf instead.
781 * This is to satisfy the CPUID specification.
783 static struct kvm_cpuid_entry2* check_cpuid_limit(struct kvm_vcpu *vcpu,
784 u32 function, u32 index)
786 struct kvm_cpuid_entry2 *maxlevel;
788 maxlevel = kvm_find_cpuid_entry(vcpu, function & 0x80000000, 0);
789 if (!maxlevel || maxlevel->eax >= function)
791 if (function & 0x80000000) {
792 maxlevel = kvm_find_cpuid_entry(vcpu, 0, 0);
796 return kvm_find_cpuid_entry(vcpu, maxlevel->eax, index);
799 void kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx, u32 *ecx, u32 *edx)
801 u32 function = *eax, index = *ecx;
802 struct kvm_cpuid_entry2 *best;
804 best = kvm_find_cpuid_entry(vcpu, function, index);
807 best = check_cpuid_limit(vcpu, function, index);
810 * Perfmon not yet supported for L2 guest.
812 if (is_guest_mode(vcpu) && function == 0xa)
821 *eax = *ebx = *ecx = *edx = 0;
822 trace_kvm_cpuid(function, *eax, *ebx, *ecx, *edx);
824 EXPORT_SYMBOL_GPL(kvm_cpuid);
826 void kvm_emulate_cpuid(struct kvm_vcpu *vcpu)
828 u32 function, eax, ebx, ecx, edx;
830 function = eax = kvm_register_read(vcpu, VCPU_REGS_RAX);
831 ecx = kvm_register_read(vcpu, VCPU_REGS_RCX);
832 kvm_cpuid(vcpu, &eax, &ebx, &ecx, &edx);
833 kvm_register_write(vcpu, VCPU_REGS_RAX, eax);
834 kvm_register_write(vcpu, VCPU_REGS_RBX, ebx);
835 kvm_register_write(vcpu, VCPU_REGS_RCX, ecx);
836 kvm_register_write(vcpu, VCPU_REGS_RDX, edx);
837 kvm_x86_ops->skip_emulated_instruction(vcpu);
839 EXPORT_SYMBOL_GPL(kvm_emulate_cpuid);