这是要修改的正确linux内核代码 - 如何进行更改以模拟CPUID代码以及需要更改的功能。谢谢
#include <linux/kvm_host.h>
#include <linux/export.h>
#include <linux/vmalloc.h>
#include <linux/uaccess.h>
#include <linux/sched/stat.h>
#include <asm/processor.h>
#include <asm/user.h>
#include <asm/fpu/xstate.h>
#include "cpuid.h"
#include "lapic.h"
#include "mmu.h"
#include "trace.h"
#include "pmu.h"
static u32 xstate_required_size(u64 xstate_bv, bool compacted)
{
int feature_bit = 0;
u32 ret = XSAVE_HDR_SIZE + XSAVE_HDR_OFFSET;
xstate_bv &= XFEATURE_MASK_EXTEND;
while (xstate_bv) {
if (xstate_bv & 0x1) {
u32 eax, ebx, ecx, edx, offset;
cpuid_count(0xD, feature_bit, &eax, &ebx, &ecx, &edx);
offset = compacted ? ret : ebx;
ret = max(ret, offset + eax);
}
xstate_bv >>= 1;
feature_bit++;
}
return ret;
}
bool kvm_mpx_supported(void)
{
return ((host_xcr0 & (XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR))
&& kvm_x86_ops->mpx_supported());
}
EXPORT_SYMBOL_GPL(kvm_mpx_supported);
u64 kvm_supported_xcr0(void)
{
u64 xcr0 = KVM_SUPPORTED_XCR0 & host_xcr0;
if (!kvm_mpx_supported())
xcr0 &= ~(XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR);
return xcr0;
}
#define F(x) bit(X86_FEATURE_##x)
/* These are scattered features in cpufeatures.h. */
#define KVM_CPUID_BIT_AVX512_4VNNIW 2
#define KVM_CPUID_BIT_AVX512_4FMAPS 3
#define KF(x) bit(KVM_CPUID_BIT_##x)
int 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 0;
/* Update OSXSAVE bit */
if (boot_cpu_has(X86_FEATURE_XSAVE) && best->function == 0x1) {
best->ecx &= ~F(OSXSAVE);
if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE))
best->ecx |= F(OSXSAVE);
}
best->edx &= ~F(APIC);
if (vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE)
best->edx |= F(APIC);
if (apic) {
if (best->ecx & F(TSC_DEADLINE_TIMER))
apic->lapic_timer.timer_mode_mask = 3 << 17;
else
apic->lapic_timer.timer_mode_mask = 1 << 17;
}
best = kvm_find_cpuid_entry(vcpu, 7, 0);
if (best) {
/* Update OSPKE bit */
if (boot_cpu_has(X86_FEATURE_PKU) && best->function == 0x7) {
best->ecx &= ~F(OSPKE);
if (kvm_read_cr4_bits(vcpu, X86_CR4_PKE))
best->ecx |= F(OSPKE);
}
}
best = kvm_find_cpuid_entry(vcpu, 0xD, 0);
if (!best) {
vcpu->arch.guest_supported_xcr0 = 0;
vcpu->arch.guest_xstate_size = XSAVE_HDR_SIZE + XSAVE_HDR_OFFSET;
} else {
vcpu->arch.guest_supported_xcr0 =
(best->eax | ((u64)best->edx << 32)) &
kvm_supported_xcr0();
vcpu->arch.guest_xstate_size = best->ebx =
xstate_required_size(vcpu->arch.xcr0, false);
}
best = kvm_find_cpuid_entry(vcpu, 0xD, 1);
if (best && (best->eax & (F(XSAVES) | F(XSAVEC))))
best->ebx = xstate_required_size(vcpu->arch.xcr0, true);
/*
* The existing code assumes virtual address is 48-bit or 57-bit in the
* canonical address checks; exit if it is ever changed.
*/
best = kvm_find_cpuid_entry(vcpu, 0x80000008, 0);
if (best) {
int vaddr_bits = (best->eax & 0xff00) >> 8;
if (vaddr_bits != 48 && vaddr_bits != 57 && vaddr_bits != 0)
return -EINVAL;
}
/* Update physical-address width */
vcpu->arch.maxphyaddr = cpuid_query_maxphyaddr(vcpu);
kvm_mmu_reset_context(vcpu);
kvm_pmu_refresh(vcpu);
return 0;
}
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 & F(NX)) && !is_efer_nx()) {
entry->edx &= ~F(NX);
printk(KERN_INFO "kvm: guest NX capability removed\n");
}
}
int cpuid_query_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;
}
EXPORT_SYMBOL_GPL(cpuid_query_maxphyaddr);
/* 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 = NULL;
r = -E2BIG;
if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
goto out;
r = -ENOMEM;
if (cpuid->nent) {
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;
}
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);
kvm_apic_set_version(vcpu);
kvm_x86_ops->cpuid_update(vcpu);
r = kvm_update_cpuid(vcpu);
out:
vfree(cpuid_entries);
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);
r = kvm_update_cpuid(vcpu);
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 int __do_cpuid_ent_emulated(struct kvm_cpuid_entry2 *entry,
u32 func, u32 index, int *nent, int maxnent)
{
switch (func) {
case 0:
entry->eax = 1; /* only one leaf currently */
++*nent;
break;
case 1:
entry->ecx = F(MOVBE);
++*nent;
break;
default:
break;
}
entry->function = func;
entry->index = index;
return 0;
}
static inline 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;
unsigned f_invpcid = kvm_x86_ops->invpcid_supported() ? F(INVPCID) : 0;
unsigned f_mpx = kvm_mpx_supported() ? F(MPX) : 0;
unsigned f_xsaves = kvm_x86_ops->xsaves_supported() ? F(XSAVES) : 0;
/* cpuid 1.edx */
const u32 kvm_cpuid_1_edx_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(CLFLUSH) |
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_cpuid_8000_0001_edx_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_cpuid_1_ecx_x86_features =
/* NOTE: MONITOR (and MWAIT) are emulated as NOP,
* but *not* advertised to guests via CPUID ! */
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 */ |
F(PCID) | 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_cpuid_8000_0001_ecx_x86_features =
F(LAHF_LM) | F(CMP_LEGACY) | 0 /*SVM*/ | 0 /* ExtApicSpace */ |
F(CR8_LEGACY) | F(ABM) | F(SSE4A) | F(MISALIGNSSE) |
F(3DNOWPREFETCH) | F(OSVW) | 0 /* IBS */ | F(XOP) |
0 /* SKINIT, WDT, LWP */ | F(FMA4) | F(TBM);
/* cpuid 0xC0000001.edx */
const u32 kvm_cpuid_C000_0001_edx_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_cpuid_7_0_ebx_x86_features =
F(FSGSBASE) | F(BMI1) | F(HLE) | F(AVX2) | F(SMEP) |
F(BMI2) | F(ERMS) | f_invpcid | F(RTM) | f_mpx | F(RDSEED) |
F(ADX) | F(SMAP) | F(AVX512IFMA) | F(AVX512F) | F(AVX512PF) |
F(AVX512ER) | F(AVX512CD) | F(CLFLUSHOPT) | F(CLWB) | F(AVX512DQ) |
F(SHA_NI) | F(AVX512BW) | F(AVX512VL);
/* cpuid 0xD.1.eax */
const u32 kvm_cpuid_D_1_eax_x86_features =
F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1) | f_xsaves;
/* cpuid 7.0.ecx*/
const u32 kvm_cpuid_7_0_ecx_x86_features =
F(AVX512VBMI) | F(LA57) | F(PKU) |
0 /*OSPKE*/ | F(AVX512_VPOPCNTDQ);
/* cpuid 7.0.edx*/
const u32 kvm_cpuid_7_0_edx_x86_features =
KF(AVX512_4VNNIW) | KF(AVX512_4FMAPS);
/* 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_cpuid_1_edx_x86_features;
cpuid_mask(&entry->edx, CPUID_1_EDX);
entry->ecx &= kvm_cpuid_1_ecx_x86_features;
cpuid_mask(&entry->ecx, CPUID_1_ECX);
/* 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 6: /* Thermal management */
entry->eax = 0x4; /* allow ARAT */
entry->ebx = 0;
entry->ecx = 0;
entry->edx = 0;
break;
case 7: {
entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
/* Mask ebx against host capability word 9 */
if (index == 0) {
entry->ebx &= kvm_cpuid_7_0_ebx_x86_features;
cpuid_mask(&entry->ebx, CPUID_7_0_EBX);
// TSC_ADJUST is emulated
entry->ebx |= F(TSC_ADJUST);
entry->ecx &= kvm_cpuid_7_0_ecx_x86_features;
cpuid_mask(&entry->ecx, CPUID_7_ECX);
/* PKU is not yet implemented for shadow paging. */
if (!tdp_enabled || !boot_cpu_has(X86_FEATURE_OSPKE))
entry->ecx &= ~F(PKU);
entry->edx &= kvm_cpuid_7_0_edx_x86_features;
entry->edx &= get_scattered_cpuid_leaf(7, 0, CPUID_EDX);
} else {
entry->ebx = 0;
entry->ecx = 0;
entry->edx = 0;
}
entry->eax = 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;
u64 supported = kvm_supported_xcr0();
entry->eax &= supported;
entry->ebx = xstate_required_size(supported, false);
entry->ecx = entry->ebx;
entry->edx &= supported >> 32;
entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
if (!supported)
break;
for (idx = 1, i = 1; idx < 64; ++idx) {
u64 mask = ((u64)1 << idx);
if (*nent >= maxnent)
goto out;
do_cpuid_1_ent(&entry[i], function, idx);
if (idx == 1) {
entry[i].eax &= kvm_cpuid_D_1_eax_x86_features;
cpuid_mask(&entry[i].eax, CPUID_D_1_EAX);
entry[i].ebx = 0;
if (entry[i].eax & (F(XSAVES)|F(XSAVEC)))
entry[i].ebx =
xstate_required_size(supported,
true);
} else {
if (entry[i].eax == 0 || !(supported & mask))
continue;
if (WARN_ON_ONCE(entry[i].ecx & 1))
continue;
}
entry[i].ecx = 0;
entry[i].edx = 0;
entry[i].flags |=
KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
++*nent;
++i;
}
break;
}
case KVM_CPUID_SIGNATURE: {
static const char signature[12] = "KVMKVMKVM\0\0";
const u32 *sigptr = (const u32 *)signature;
entry->eax = KVM_CPUID_FEATURES;
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_PV_EOI) |
(1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) |
(1 << KVM_FEATURE_PV_UNHALT);
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_cpuid_8000_0001_edx_x86_features;
cpuid_mask(&entry->edx, CPUID_8000_0001_EDX);
entry->ecx &= kvm_cpuid_8000_0001_ecx_x86_features;
cpuid_mask(&entry->ecx, CPUID_8000_0001_ECX);
break;
case 0x80000007: /* Advanced power management */
/* invariant TSC is CPUID.80000007H:EDX[8] */
entry->edx &= (1 << 8);
/* mask against host */
entry->edx &= boot_cpu_data.x86_power;
entry->eax = entry->ebx = entry->ecx = 0;
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_cpuid_C000_0001_edx_x86_features;
cpuid_mask(&entry->edx, CPUID_C000_0001_EDX);
break;
case 3: /* Processor serial number */
case 5: /* MONITOR/MWAIT */
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;
}
static int do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 func,
u32 idx, int *nent, int maxnent, unsigned int type)
{
if (type == KVM_GET_EMULATED_CPUID)
return __do_cpuid_ent_emulated(entry, func, idx, nent, maxnent);
return __do_cpuid_ent(entry, func, idx, nent, maxnent);
}
#undef F
struct kvm_cpuid_param {
u32 func;
u32 idx;
bool has_leaf_count;
bool (*qualifier)(const struct kvm_cpuid_param *param);
};
static bool is_centaur_cpu(const struct kvm_cpuid_param *param)
{
return boot_cpu_data.x86_vendor == X86_VENDOR_CENTAUR;
}
static bool sanity_check_entries(struct kvm_cpuid_entry2 __user *entries,
__u32 num_entries, unsigned int ioctl_type)
{
int i;
__u32 pad[3];
if (ioctl_type != KVM_GET_EMULATED_CPUID)
return false;
/*
* We want to make sure that ->padding is being passed clean from
* userspace in case we want to use it for something in the future.
*
* Sadly, this wasn't enforced for KVM_GET_SUPPORTED_CPUID and so we
* have to give ourselves satisfied only with the emulated side. /me
* sheds a tear.
*/
for (i = 0; i < num_entries; i++) {
if (copy_from_user(pad, entries[i].padding, sizeof(pad)))
return true;
if (pad[0] || pad[1] || pad[2])
return true;
}
return false;
}
int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid,
struct kvm_cpuid_entry2 __user *entries,
unsigned int type)
{
struct kvm_cpuid_entry2 *cpuid_entries;
int limit, nent = 0, r = -E2BIG, i;
u32 func;
static const 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;
if (sanity_check_entries(entries, cpuid->nent, type))
return -EINVAL;
r = -ENOMEM;
cpuid_entries = vzalloc(sizeof(struct kvm_cpuid_entry2) * cpuid->nent);
if (!cpuid_entries)
goto out;
r = 0;
for (i = 0; i < ARRAY_SIZE(param); i++) {
const struct kvm_cpuid_param *ent = ¶m[i];
if (ent->qualifier && !ent->qualifier(ent))
continue;
r = do_cpuid_ent(&cpuid_entries[nent], ent->func, ent->idx,
&nent, cpuid->nent, type);
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, type);
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];
struct kvm_cpuid_entry2 *ej;
int j = i;
int 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 */
do {
j = (j + 1) % nent;
ej = &vcpu->arch.cpuid_entries[j];
} while (ej->function != e->function);
ej->flags |= KVM_CPUID_FLAG_STATE_READ_NEXT;
return j;
}
/* 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);
/*
* 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);
}
bool kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx,
u32 *ecx, u32 *edx, bool check_limit)
{
u32 function = *eax, index = *ecx;
struct kvm_cpuid_entry2 *best;
bool entry_found = true;
best = kvm_find_cpuid_entry(vcpu, function, index);
if (!best) {
entry_found = false;
if (!check_limit)
goto out;
best = check_cpuid_limit(vcpu, function, index);
}
out:
if (best) {
*eax = best->eax;
*ebx = best->ebx;
*ecx = best->ecx;
*edx = best->edx;
} else
*eax = *ebx = *ecx = *edx = 0;
trace_kvm_cpuid(function, *eax, *ebx, *ecx, *edx, entry_found);
return entry_found;
}
EXPORT_SYMBOL_GPL(kvm_cpuid);
int kvm_emulate_cpuid(struct kvm_vcpu *vcpu)
{
u32 eax, ebx, ecx, edx;
if (cpuid_fault_enabled(vcpu) && !kvm_require_cpl(vcpu, 0))
return 1;
eax = kvm_register_read(vcpu, VCPU_REGS_RAX);
ecx = kvm_register_read(vcpu, VCPU_REGS_RCX);
kvm_cpuid(vcpu, &eax, &ebx, &ecx, &edx, true);
kvm_register_write(vcpu, VCPU_REGS_RAX, eax);
kvm_register_write(vcpu, VCPU_REGS_RBX, ebx);
kvm_register_write(vcpu, VCPU_REGS_RCX, ecx);
kvm_register_write(vcpu, VCPU_REGS_RDX, edx);
return kvm_skip_emulated_instruction(vcpu);
}
EXPORT_SYMBOL_GPL(kvm_emulate_cpuid);
我想在Linux树中添加/编辑代码到KVM（从github克隆内核），重建内核并启动到修改后的内核并运行用户模式c程序，如
#include <stdio.h>
#include <cpuid.h>
#include <stdint.h>
int
main(int argc, char **argv)
{
uint32_t eax, ebx, ecx, edx;
__cpuid(0x0, eax, ebx, ecx, edx);
printf("CPUID(0x0).EAX=0x%x\n", eax);
printf("CPUID(0x0).EBX=0x%x\n", ebx);
printf("CPUID(0x0).ECX=0x%x\n", ecx);
printf("CPUID(0x0).EDX=0x%x\n", edx);
return 0;
}
获得类似
的输出CPUID(0x0) Brand String = GenuineIntel
CPUID(0x4FFFFFFF)
CPUID(0x0) Brand String = SOME TEXT
CPUID(0x4FFFFFFF)
答案 0 :(得分：2)
内核没有实现任何特定的CPUID仿真本身;这是由KVM客户实施的，如QEMU。例如，here's the relevant code in QEMU已经实现了许多虚构的处理器品牌，例如＆＃34; QEMU虚拟CPU＆＃34;。
此外，KVM CPUID仿真仅影响运行该内核的计算机托管的虚拟机。它不会影响该计算机上的普通用户空间应用程序。
答案 1 :(得分：0)
您需要在Linux内核中修改arch/x86/kvm/x86.c。
使用以下github项目作为参考：https://github.com/sowmyagowri/Modify-CPUID