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Diffstat (limited to 'arch/x86/kvm/cpuid.c')
-rw-r--r--arch/x86/kvm/cpuid.c670
1 files changed, 670 insertions, 0 deletions
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
new file mode 100644
index 00000000000..89b02bfaaca
--- /dev/null
+++ b/arch/x86/kvm/cpuid.c
@@ -0,0 +1,670 @@
+/*
+ * Kernel-based Virtual Machine driver for Linux
+ * cpuid support routines
+ *
+ * derived from arch/x86/kvm/x86.c
+ *
+ * Copyright 2011 Red Hat, Inc. and/or its affiliates.
+ * Copyright IBM Corporation, 2008
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#include <linux/kvm_host.h>
+#include <linux/module.h>
+#include <linux/vmalloc.h>
+#include <linux/uaccess.h>
+#include <asm/user.h>
+#include <asm/xsave.h>
+#include "cpuid.h"
+#include "lapic.h"
+#include "mmu.h"
+#include "trace.h"
+
+void kvm_update_cpuid(struct kvm_vcpu *vcpu)
+{
+ struct kvm_cpuid_entry2 *best;
+ struct kvm_lapic *apic = vcpu->arch.apic;
+
+ best = kvm_find_cpuid_entry(vcpu, 1, 0);
+ if (!best)
+ return;
+
+ /* Update OSXSAVE bit */
+ if (cpu_has_xsave && best->function == 0x1) {
+ best->ecx &= ~(bit(X86_FEATURE_OSXSAVE));
+ if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE))
+ best->ecx |= bit(X86_FEATURE_OSXSAVE);
+ }
+
+ if (apic) {
+ if (best->ecx & bit(X86_FEATURE_TSC_DEADLINE_TIMER))
+ apic->lapic_timer.timer_mode_mask = 3 << 17;
+ else
+ apic->lapic_timer.timer_mode_mask = 1 << 17;
+ }
+
+ kvm_pmu_cpuid_update(vcpu);
+}
+
+static int is_efer_nx(void)
+{
+ unsigned long long efer = 0;
+
+ rdmsrl_safe(MSR_EFER, &efer);
+ return efer & EFER_NX;
+}
+
+static void cpuid_fix_nx_cap(struct kvm_vcpu *vcpu)
+{
+ int i;
+ struct kvm_cpuid_entry2 *e, *entry;
+
+ entry = NULL;
+ for (i = 0; i < vcpu->arch.cpuid_nent; ++i) {
+ e = &vcpu->arch.cpuid_entries[i];
+ if (e->function == 0x80000001) {
+ entry = e;
+ break;
+ }
+ }
+ if (entry && (entry->edx & (1 << 20)) && !is_efer_nx()) {
+ entry->edx &= ~(1 << 20);
+ printk(KERN_INFO "kvm: guest NX capability removed\n");
+ }
+}
+
+/* when an old userspace process fills a new kernel module */
+int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
+ struct kvm_cpuid *cpuid,
+ struct kvm_cpuid_entry __user *entries)
+{
+ int r, i;
+ struct kvm_cpuid_entry *cpuid_entries;
+
+ r = -E2BIG;
+ if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
+ goto out;
+ r = -ENOMEM;
+ cpuid_entries = vmalloc(sizeof(struct kvm_cpuid_entry) * cpuid->nent);
+ if (!cpuid_entries)
+ goto out;
+ r = -EFAULT;
+ if (copy_from_user(cpuid_entries, entries,
+ cpuid->nent * sizeof(struct kvm_cpuid_entry)))
+ goto out_free;
+ for (i = 0; i < cpuid->nent; i++) {
+ vcpu->arch.cpuid_entries[i].function = cpuid_entries[i].function;
+ vcpu->arch.cpuid_entries[i].eax = cpuid_entries[i].eax;
+ vcpu->arch.cpuid_entries[i].ebx = cpuid_entries[i].ebx;
+ vcpu->arch.cpuid_entries[i].ecx = cpuid_entries[i].ecx;
+ vcpu->arch.cpuid_entries[i].edx = cpuid_entries[i].edx;
+ vcpu->arch.cpuid_entries[i].index = 0;
+ vcpu->arch.cpuid_entries[i].flags = 0;
+ vcpu->arch.cpuid_entries[i].padding[0] = 0;
+ vcpu->arch.cpuid_entries[i].padding[1] = 0;
+ vcpu->arch.cpuid_entries[i].padding[2] = 0;
+ }
+ vcpu->arch.cpuid_nent = cpuid->nent;
+ cpuid_fix_nx_cap(vcpu);
+ r = 0;
+ kvm_apic_set_version(vcpu);
+ kvm_x86_ops->cpuid_update(vcpu);
+ kvm_update_cpuid(vcpu);
+
+out_free:
+ vfree(cpuid_entries);
+out:
+ return r;
+}
+
+int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
+ struct kvm_cpuid2 *cpuid,
+ struct kvm_cpuid_entry2 __user *entries)
+{
+ int r;
+
+ r = -E2BIG;
+ if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
+ goto out;
+ r = -EFAULT;
+ if (copy_from_user(&vcpu->arch.cpuid_entries, entries,
+ cpuid->nent * sizeof(struct kvm_cpuid_entry2)))
+ goto out;
+ vcpu->arch.cpuid_nent = cpuid->nent;
+ kvm_apic_set_version(vcpu);
+ kvm_x86_ops->cpuid_update(vcpu);
+ kvm_update_cpuid(vcpu);
+ return 0;
+
+out:
+ return r;
+}
+
+int kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu *vcpu,
+ struct kvm_cpuid2 *cpuid,
+ struct kvm_cpuid_entry2 __user *entries)
+{
+ int r;
+
+ r = -E2BIG;
+ if (cpuid->nent < vcpu->arch.cpuid_nent)
+ goto out;
+ r = -EFAULT;
+ if (copy_to_user(entries, &vcpu->arch.cpuid_entries,
+ vcpu->arch.cpuid_nent * sizeof(struct kvm_cpuid_entry2)))
+ goto out;
+ return 0;
+
+out:
+ cpuid->nent = vcpu->arch.cpuid_nent;
+ return r;
+}
+
+static void cpuid_mask(u32 *word, int wordnum)
+{
+ *word &= boot_cpu_data.x86_capability[wordnum];
+}
+
+static void do_cpuid_1_ent(struct kvm_cpuid_entry2 *entry, u32 function,
+ u32 index)
+{
+ entry->function = function;
+ entry->index = index;
+ cpuid_count(entry->function, entry->index,
+ &entry->eax, &entry->ebx, &entry->ecx, &entry->edx);
+ entry->flags = 0;
+}
+
+static bool supported_xcr0_bit(unsigned bit)
+{
+ u64 mask = ((u64)1 << bit);
+
+ return mask & (XSTATE_FP | XSTATE_SSE | XSTATE_YMM) & host_xcr0;
+}
+
+#define F(x) bit(X86_FEATURE_##x)
+
+static int do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
+ u32 index, int *nent, int maxnent)
+{
+ int r;
+ unsigned f_nx = is_efer_nx() ? F(NX) : 0;
+#ifdef CONFIG_X86_64
+ unsigned f_gbpages = (kvm_x86_ops->get_lpage_level() == PT_PDPE_LEVEL)
+ ? F(GBPAGES) : 0;
+ unsigned f_lm = F(LM);
+#else
+ unsigned f_gbpages = 0;
+ unsigned f_lm = 0;
+#endif
+ unsigned f_rdtscp = kvm_x86_ops->rdtscp_supported() ? F(RDTSCP) : 0;
+
+ /* cpuid 1.edx */
+ const u32 kvm_supported_word0_x86_features =
+ F(FPU) | F(VME) | F(DE) | F(PSE) |
+ F(TSC) | F(MSR) | F(PAE) | F(MCE) |
+ F(CX8) | F(APIC) | 0 /* Reserved */ | F(SEP) |
+ F(MTRR) | F(PGE) | F(MCA) | F(CMOV) |
+ F(PAT) | F(PSE36) | 0 /* PSN */ | F(CLFLSH) |
+ 0 /* Reserved, DS, ACPI */ | F(MMX) |
+ F(FXSR) | F(XMM) | F(XMM2) | F(SELFSNOOP) |
+ 0 /* HTT, TM, Reserved, PBE */;
+ /* cpuid 0x80000001.edx */
+ const u32 kvm_supported_word1_x86_features =
+ F(FPU) | F(VME) | F(DE) | F(PSE) |
+ F(TSC) | F(MSR) | F(PAE) | F(MCE) |
+ F(CX8) | F(APIC) | 0 /* Reserved */ | F(SYSCALL) |
+ F(MTRR) | F(PGE) | F(MCA) | F(CMOV) |
+ F(PAT) | F(PSE36) | 0 /* Reserved */ |
+ f_nx | 0 /* Reserved */ | F(MMXEXT) | F(MMX) |
+ F(FXSR) | F(FXSR_OPT) | f_gbpages | f_rdtscp |
+ 0 /* Reserved */ | f_lm | F(3DNOWEXT) | F(3DNOW);
+ /* cpuid 1.ecx */
+ const u32 kvm_supported_word4_x86_features =
+ F(XMM3) | F(PCLMULQDQ) | 0 /* DTES64, MONITOR */ |
+ 0 /* DS-CPL, VMX, SMX, EST */ |
+ 0 /* TM2 */ | F(SSSE3) | 0 /* CNXT-ID */ | 0 /* Reserved */ |
+ F(FMA) | F(CX16) | 0 /* xTPR Update, PDCM */ |
+ 0 /* Reserved, DCA */ | F(XMM4_1) |
+ F(XMM4_2) | F(X2APIC) | F(MOVBE) | F(POPCNT) |
+ 0 /* Reserved*/ | F(AES) | F(XSAVE) | 0 /* OSXSAVE */ | F(AVX) |
+ F(F16C) | F(RDRAND);
+ /* cpuid 0x80000001.ecx */
+ const u32 kvm_supported_word6_x86_features =
+ F(LAHF_LM) | F(CMP_LEGACY) | 0 /*SVM*/ | 0 /* ExtApicSpace */ |
+ F(CR8_LEGACY) | F(ABM) | F(SSE4A) | F(MISALIGNSSE) |
+ F(3DNOWPREFETCH) | 0 /* OSVW */ | 0 /* IBS */ | F(XOP) |
+ 0 /* SKINIT, WDT, LWP */ | F(FMA4) | F(TBM);
+
+ /* cpuid 0xC0000001.edx */
+ const u32 kvm_supported_word5_x86_features =
+ F(XSTORE) | F(XSTORE_EN) | F(XCRYPT) | F(XCRYPT_EN) |
+ F(ACE2) | F(ACE2_EN) | F(PHE) | F(PHE_EN) |
+ F(PMM) | F(PMM_EN);
+
+ /* cpuid 7.0.ebx */
+ const u32 kvm_supported_word9_x86_features =
+ F(FSGSBASE) | F(BMI1) | F(AVX2) | F(SMEP) | F(BMI2) | F(ERMS);
+
+ /* all calls to cpuid_count() should be made on the same cpu */
+ get_cpu();
+
+ r = -E2BIG;
+
+ if (*nent >= maxnent)
+ goto out;
+
+ do_cpuid_1_ent(entry, function, index);
+ ++*nent;
+
+ switch (function) {
+ case 0:
+ entry->eax = min(entry->eax, (u32)0xd);
+ break;
+ case 1:
+ entry->edx &= kvm_supported_word0_x86_features;
+ cpuid_mask(&entry->edx, 0);
+ entry->ecx &= kvm_supported_word4_x86_features;
+ cpuid_mask(&entry->ecx, 4);
+ /* we support x2apic emulation even if host does not support
+ * it since we emulate x2apic in software */
+ entry->ecx |= F(X2APIC);
+ break;
+ /* function 2 entries are STATEFUL. That is, repeated cpuid commands
+ * may return different values. This forces us to get_cpu() before
+ * issuing the first command, and also to emulate this annoying behavior
+ * in kvm_emulate_cpuid() using KVM_CPUID_FLAG_STATE_READ_NEXT */
+ case 2: {
+ int t, times = entry->eax & 0xff;
+
+ entry->flags |= KVM_CPUID_FLAG_STATEFUL_FUNC;
+ entry->flags |= KVM_CPUID_FLAG_STATE_READ_NEXT;
+ for (t = 1; t < times; ++t) {
+ if (*nent >= maxnent)
+ goto out;
+
+ do_cpuid_1_ent(&entry[t], function, 0);
+ entry[t].flags |= KVM_CPUID_FLAG_STATEFUL_FUNC;
+ ++*nent;
+ }
+ break;
+ }
+ /* function 4 has additional index. */
+ case 4: {
+ int i, cache_type;
+
+ entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
+ /* read more entries until cache_type is zero */
+ for (i = 1; ; ++i) {
+ if (*nent >= maxnent)
+ goto out;
+
+ cache_type = entry[i - 1].eax & 0x1f;
+ if (!cache_type)
+ break;
+ do_cpuid_1_ent(&entry[i], function, i);
+ entry[i].flags |=
+ KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
+ ++*nent;
+ }
+ break;
+ }
+ case 7: {
+ entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
+ /* Mask ebx against host capbability word 9 */
+ if (index == 0) {
+ entry->ebx &= kvm_supported_word9_x86_features;
+ cpuid_mask(&entry->ebx, 9);
+ } else
+ entry->ebx = 0;
+ entry->eax = 0;
+ entry->ecx = 0;
+ entry->edx = 0;
+ break;
+ }
+ case 9:
+ break;
+ case 0xa: { /* Architectural Performance Monitoring */
+ struct x86_pmu_capability cap;
+ union cpuid10_eax eax;
+ union cpuid10_edx edx;
+
+ perf_get_x86_pmu_capability(&cap);
+
+ /*
+ * Only support guest architectural pmu on a host
+ * with architectural pmu.
+ */
+ if (!cap.version)
+ memset(&cap, 0, sizeof(cap));
+
+ eax.split.version_id = min(cap.version, 2);
+ eax.split.num_counters = cap.num_counters_gp;
+ eax.split.bit_width = cap.bit_width_gp;
+ eax.split.mask_length = cap.events_mask_len;
+
+ edx.split.num_counters_fixed = cap.num_counters_fixed;
+ edx.split.bit_width_fixed = cap.bit_width_fixed;
+ edx.split.reserved = 0;
+
+ entry->eax = eax.full;
+ entry->ebx = cap.events_mask;
+ entry->ecx = 0;
+ entry->edx = edx.full;
+ break;
+ }
+ /* function 0xb has additional index. */
+ case 0xb: {
+ int i, level_type;
+
+ entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
+ /* read more entries until level_type is zero */
+ for (i = 1; ; ++i) {
+ if (*nent >= maxnent)
+ goto out;
+
+ level_type = entry[i - 1].ecx & 0xff00;
+ if (!level_type)
+ break;
+ do_cpuid_1_ent(&entry[i], function, i);
+ entry[i].flags |=
+ KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
+ ++*nent;
+ }
+ break;
+ }
+ case 0xd: {
+ int idx, i;
+
+ entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
+ for (idx = 1, i = 1; idx < 64; ++idx) {
+ if (*nent >= maxnent)
+ goto out;
+
+ do_cpuid_1_ent(&entry[i], function, idx);
+ if (entry[i].eax == 0 || !supported_xcr0_bit(idx))
+ continue;
+ entry[i].flags |=
+ KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
+ ++*nent;
+ ++i;
+ }
+ break;
+ }
+ case KVM_CPUID_SIGNATURE: {
+ char signature[12] = "KVMKVMKVM\0\0";
+ u32 *sigptr = (u32 *)signature;
+ entry->eax = 0;
+ entry->ebx = sigptr[0];
+ entry->ecx = sigptr[1];
+ entry->edx = sigptr[2];
+ break;
+ }
+ case KVM_CPUID_FEATURES:
+ entry->eax = (1 << KVM_FEATURE_CLOCKSOURCE) |
+ (1 << KVM_FEATURE_NOP_IO_DELAY) |
+ (1 << KVM_FEATURE_CLOCKSOURCE2) |
+ (1 << KVM_FEATURE_ASYNC_PF) |
+ (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT);
+
+ if (sched_info_on())
+ entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);
+
+ entry->ebx = 0;
+ entry->ecx = 0;
+ entry->edx = 0;
+ break;
+ case 0x80000000:
+ entry->eax = min(entry->eax, 0x8000001a);
+ break;
+ case 0x80000001:
+ entry->edx &= kvm_supported_word1_x86_features;
+ cpuid_mask(&entry->edx, 1);
+ entry->ecx &= kvm_supported_word6_x86_features;
+ cpuid_mask(&entry->ecx, 6);
+ break;
+ case 0x80000008: {
+ unsigned g_phys_as = (entry->eax >> 16) & 0xff;
+ unsigned virt_as = max((entry->eax >> 8) & 0xff, 48U);
+ unsigned phys_as = entry->eax & 0xff;
+
+ if (!g_phys_as)
+ g_phys_as = phys_as;
+ entry->eax = g_phys_as | (virt_as << 8);
+ entry->ebx = entry->edx = 0;
+ break;
+ }
+ case 0x80000019:
+ entry->ecx = entry->edx = 0;
+ break;
+ case 0x8000001a:
+ break;
+ case 0x8000001d:
+ break;
+ /*Add support for Centaur's CPUID instruction*/
+ case 0xC0000000:
+ /*Just support up to 0xC0000004 now*/
+ entry->eax = min(entry->eax, 0xC0000004);
+ break;
+ case 0xC0000001:
+ entry->edx &= kvm_supported_word5_x86_features;
+ cpuid_mask(&entry->edx, 5);
+ break;
+ case 3: /* Processor serial number */
+ case 5: /* MONITOR/MWAIT */
+ case 6: /* Thermal management */
+ case 0x80000007: /* Advanced power management */
+ case 0xC0000002:
+ case 0xC0000003:
+ case 0xC0000004:
+ default:
+ entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
+ break;
+ }
+
+ kvm_x86_ops->set_supported_cpuid(function, entry);
+
+ r = 0;
+
+out:
+ put_cpu();
+
+ return r;
+}
+
+#undef F
+
+struct kvm_cpuid_param {
+ u32 func;
+ u32 idx;
+ bool has_leaf_count;
+ bool (*qualifier)(struct kvm_cpuid_param *param);
+};
+
+static bool is_centaur_cpu(struct kvm_cpuid_param *param)
+{
+ return boot_cpu_data.x86_vendor == X86_VENDOR_CENTAUR;
+}
+
+int kvm_dev_ioctl_get_supported_cpuid(struct kvm_cpuid2 *cpuid,
+ struct kvm_cpuid_entry2 __user *entries)
+{
+ struct kvm_cpuid_entry2 *cpuid_entries;
+ int limit, nent = 0, r = -E2BIG, i;
+ u32 func;
+ static struct kvm_cpuid_param param[] = {
+ { .func = 0, .has_leaf_count = true },
+ { .func = 0x80000000, .has_leaf_count = true },
+ { .func = 0xC0000000, .qualifier = is_centaur_cpu, .has_leaf_count = true },
+ { .func = KVM_CPUID_SIGNATURE },
+ { .func = KVM_CPUID_FEATURES },
+ };
+
+ if (cpuid->nent < 1)
+ goto out;
+ if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
+ cpuid->nent = KVM_MAX_CPUID_ENTRIES;
+ r = -ENOMEM;
+ cpuid_entries = vmalloc(sizeof(struct kvm_cpuid_entry2) * cpuid->nent);
+ if (!cpuid_entries)
+ goto out;
+
+ r = 0;
+ for (i = 0; i < ARRAY_SIZE(param); i++) {
+ struct kvm_cpuid_param *ent = &param[i];
+
+ if (ent->qualifier && !ent->qualifier(ent))
+ continue;
+
+ r = do_cpuid_ent(&cpuid_entries[nent], ent->func, ent->idx,
+ &nent, cpuid->nent);
+
+ if (r)
+ goto out_free;
+
+ if (!ent->has_leaf_count)
+ continue;
+
+ limit = cpuid_entries[nent - 1].eax;
+ for (func = ent->func + 1; func <= limit && nent < cpuid->nent && r == 0; ++func)
+ r = do_cpuid_ent(&cpuid_entries[nent], func, ent->idx,
+ &nent, cpuid->nent);
+
+ if (r)
+ goto out_free;
+ }
+
+ r = -EFAULT;
+ if (copy_to_user(entries, cpuid_entries,
+ nent * sizeof(struct kvm_cpuid_entry2)))
+ goto out_free;
+ cpuid->nent = nent;
+ r = 0;
+
+out_free:
+ vfree(cpuid_entries);
+out:
+ return r;
+}
+
+static int move_to_next_stateful_cpuid_entry(struct kvm_vcpu *vcpu, int i)
+{
+ struct kvm_cpuid_entry2 *e = &vcpu->arch.cpuid_entries[i];
+ int j, nent = vcpu->arch.cpuid_nent;
+
+ e->flags &= ~KVM_CPUID_FLAG_STATE_READ_NEXT;
+ /* when no next entry is found, the current entry[i] is reselected */
+ for (j = i + 1; ; j = (j + 1) % nent) {
+ struct kvm_cpuid_entry2 *ej = &vcpu->arch.cpuid_entries[j];
+ if (ej->function == e->function) {
+ ej->flags |= KVM_CPUID_FLAG_STATE_READ_NEXT;
+ return j;
+ }
+ }
+ return 0; /* silence gcc, even though control never reaches here */
+}
+
+/* find an entry with matching function, matching index (if needed), and that
+ * should be read next (if it's stateful) */
+static int is_matching_cpuid_entry(struct kvm_cpuid_entry2 *e,
+ u32 function, u32 index)
+{
+ if (e->function != function)
+ return 0;
+ if ((e->flags & KVM_CPUID_FLAG_SIGNIFCANT_INDEX) && e->index != index)
+ return 0;
+ if ((e->flags & KVM_CPUID_FLAG_STATEFUL_FUNC) &&
+ !(e->flags & KVM_CPUID_FLAG_STATE_READ_NEXT))
+ return 0;
+ return 1;
+}
+
+struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
+ u32 function, u32 index)
+{
+ int i;
+ struct kvm_cpuid_entry2 *best = NULL;
+
+ for (i = 0; i < vcpu->arch.cpuid_nent; ++i) {
+ struct kvm_cpuid_entry2 *e;
+
+ e = &vcpu->arch.cpuid_entries[i];
+ if (is_matching_cpuid_entry(e, function, index)) {
+ if (e->flags & KVM_CPUID_FLAG_STATEFUL_FUNC)
+ move_to_next_stateful_cpuid_entry(vcpu, i);
+ best = e;
+ break;
+ }
+ }
+ return best;
+}
+EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry);
+
+int cpuid_maxphyaddr(struct kvm_vcpu *vcpu)
+{
+ struct kvm_cpuid_entry2 *best;
+
+ best = kvm_find_cpuid_entry(vcpu, 0x80000000, 0);
+ if (!best || best->eax < 0x80000008)
+ goto not_found;
+ best = kvm_find_cpuid_entry(vcpu, 0x80000008, 0);
+ if (best)
+ return best->eax & 0xff;
+not_found:
+ return 36;
+}
+
+/*
+ * If no match is found, check whether we exceed the vCPU's limit
+ * and return the content of the highest valid _standard_ leaf instead.
+ * This is to satisfy the CPUID specification.
+ */
+static struct kvm_cpuid_entry2* check_cpuid_limit(struct kvm_vcpu *vcpu,
+ u32 function, u32 index)
+{
+ struct kvm_cpuid_entry2 *maxlevel;
+
+ maxlevel = kvm_find_cpuid_entry(vcpu, function & 0x80000000, 0);
+ if (!maxlevel || maxlevel->eax >= function)
+ return NULL;
+ if (function & 0x80000000) {
+ maxlevel = kvm_find_cpuid_entry(vcpu, 0, 0);
+ if (!maxlevel)
+ return NULL;
+ }
+ return kvm_find_cpuid_entry(vcpu, maxlevel->eax, index);
+}
+
+void kvm_emulate_cpuid(struct kvm_vcpu *vcpu)
+{
+ u32 function, index;
+ struct kvm_cpuid_entry2 *best;
+
+ function = kvm_register_read(vcpu, VCPU_REGS_RAX);
+ index = kvm_register_read(vcpu, VCPU_REGS_RCX);
+ kvm_register_write(vcpu, VCPU_REGS_RAX, 0);
+ kvm_register_write(vcpu, VCPU_REGS_RBX, 0);
+ kvm_register_write(vcpu, VCPU_REGS_RCX, 0);
+ kvm_register_write(vcpu, VCPU_REGS_RDX, 0);
+ best = kvm_find_cpuid_entry(vcpu, function, index);
+
+ if (!best)
+ best = check_cpuid_limit(vcpu, function, index);
+
+ if (best) {
+ kvm_register_write(vcpu, VCPU_REGS_RAX, best->eax);
+ kvm_register_write(vcpu, VCPU_REGS_RBX, best->ebx);
+ kvm_register_write(vcpu, VCPU_REGS_RCX, best->ecx);
+ kvm_register_write(vcpu, VCPU_REGS_RDX, best->edx);
+ }
+ kvm_x86_ops->skip_emulated_instruction(vcpu);
+ trace_kvm_cpuid(function,
+ kvm_register_read(vcpu, VCPU_REGS_RAX),
+ kvm_register_read(vcpu, VCPU_REGS_RBX),
+ kvm_register_read(vcpu, VCPU_REGS_RCX),
+ kvm_register_read(vcpu, VCPU_REGS_RDX));
+}
+EXPORT_SYMBOL_GPL(kvm_emulate_cpuid);
generated by cgit v1.2.3-70-g09d2 (git 2.51.2) at 2025-11-04 08:35:38 +0000