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KVM: x86: Introduce kvm_cpu_caps to replace runtime CPUID masking

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Calculate the CPUID masks for KVM_GET_SUPPORTED_CPUID at load time using
what is effectively a KVM-adjusted copy of boot_cpu_data, or more
precisely, the x86_capability array in boot_cpu_data.

In terms of KVM support, the vast majority of CPUID feature bits are
constant, and *all* feature support is known at KVM load time.  Rather
than apply boot_cpu_data, which is effectively read-only after init,
at runtime, copy it into a KVM-specific array and use *that* to mask
CPUID registers.

In additional to consolidating the masking, kvm_cpu_caps can be adjusted
by SVM/VMX at load time and thus eliminate all feature bit manipulation
in ->set_supported_cpuid().

Opportunistically clean up a few warts:

  - Replace bare "unsigned" with "unsigned int" when a feature flag is
    captured in a local variable, e.g. f_nx.

  - Sort the CPUID masks by function, index and register (alphabetically
    for registers, i.e. EBX comes before ECX/EDX).

  - Remove the superfluous /* cpuid 7.0.ecx */ comments.

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
[Call kvm_set_cpu_caps from kvm_x86_ops->hardware_setup due to fixed
 GBPAGES patch. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2020-03-02 15:56:41 -08:00 committed by Paolo Bonzini
parent 9e6d01c2d9
commit 66a6950f99
4 changed files with 151 additions and 108 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

233
arch/x86/kvm/cpuid.c
View File

@ -24,6 +24,13 @@
#include "trace.h"
#include "pmu.h"
/*
* Unlike "struct cpuinfo_x86.x86_capability", kvm_cpu_caps doesn't need to be
* aligned to sizeof(unsigned long) because it's not accessed via bitops.
*/
u32 kvm_cpu_caps[NCAPINTS] __read_mostly;
EXPORT_SYMBOL_GPL(kvm_cpu_caps);
static u32 xstate_required_size(u64 xstate_bv, bool compacted)
{
int feature_bit = 0;
@ -254,6 +261,123 @@ out:
return r;
}
static __always_inline void kvm_cpu_cap_mask(enum cpuid_leafs leaf, u32 mask)
{
reverse_cpuid_check(leaf);
kvm_cpu_caps[leaf] &= mask;
}
void kvm_set_cpu_caps(void)
{
unsigned int f_nx = is_efer_nx() ? F(NX) : 0;
#ifdef CONFIG_X86_64
unsigned int f_gbpages = F(GBPAGES);
unsigned int f_lm = F(LM);
#else
unsigned int f_gbpages = 0;
unsigned int f_lm = 0;
#endif
BUILD_BUG_ON(sizeof(kvm_cpu_caps) >
sizeof(boot_cpu_data.x86_capability));
memcpy(&kvm_cpu_caps, &boot_cpu_data.x86_capability,
sizeof(kvm_cpu_caps));
kvm_cpu_cap_mask(CPUID_1_ECX,
/*
* 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)
);
kvm_cpu_cap_mask(CPUID_1_EDX,
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 */
);
kvm_cpu_cap_mask(CPUID_7_0_EBX,
F(FSGSBASE) | F(BMI1) | F(HLE) | F(AVX2) | F(SMEP) |
F(BMI2) | F(ERMS) | 0 /*INVPCID*/ | F(RTM) | 0 /*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) | 0 /*INTEL_PT*/
);
kvm_cpu_cap_mask(CPUID_7_ECX,
F(AVX512VBMI) | F(LA57) | 0 /*PKU*/ | 0 /*OSPKE*/ | F(RDPID) |
F(AVX512_VPOPCNTDQ) | F(UMIP) | F(AVX512_VBMI2) | F(GFNI) |
F(VAES) | F(VPCLMULQDQ) | F(AVX512_VNNI) | F(AVX512_BITALG) |
F(CLDEMOTE) | F(MOVDIRI) | F(MOVDIR64B) | 0 /*WAITPKG*/
);
/* Set LA57 based on hardware capability. */
if (cpuid_ecx(7) & F(LA57))
kvm_cpu_cap_set(X86_FEATURE_LA57);
kvm_cpu_cap_mask(CPUID_7_EDX,
F(AVX512_4VNNIW) | F(AVX512_4FMAPS) | F(SPEC_CTRL) |
F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES) | F(INTEL_STIBP) |
F(MD_CLEAR)
);
kvm_cpu_cap_mask(CPUID_7_1_EAX,
F(AVX512_BF16)
);
kvm_cpu_cap_mask(CPUID_D_1_EAX,
F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1) | F(XSAVES)
);
kvm_cpu_cap_mask(CPUID_8000_0001_ECX,
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) |
F(TOPOEXT) | F(PERFCTR_CORE)
);
kvm_cpu_cap_mask(CPUID_8000_0001_EDX,
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)
);
if (!tdp_enabled && IS_ENABLED(CONFIG_X86_64))
kvm_cpu_cap_set(X86_FEATURE_GBPAGES);
kvm_cpu_cap_mask(CPUID_8000_0008_EBX,
F(CLZERO) | F(XSAVEERPTR) |
F(WBNOINVD) | F(AMD_IBPB) | F(AMD_IBRS) | F(AMD_SSBD) | F(VIRT_SSBD) |
F(AMD_SSB_NO) | F(AMD_STIBP) | F(AMD_STIBP_ALWAYS_ON)
);
kvm_cpu_cap_mask(CPUID_C000_0001_EDX,
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)
);
}
EXPORT_SYMBOL_GPL(kvm_set_cpu_caps);
struct kvm_cpuid_array {
struct kvm_cpuid_entry2 *entries;
const int maxnent;
@ -331,48 +455,13 @@ static int __do_cpuid_func_emulated(struct kvm_cpuid_array *array, u32 func)
static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry)
{
unsigned f_la57;
/* 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) | 0 /*INVPCID*/ | F(RTM) | 0 /*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) | 0 /*INTEL_PT*/;
/* cpuid 7.0.ecx*/
const u32 kvm_cpuid_7_0_ecx_x86_features =
F(AVX512VBMI) | F(LA57) | 0 /*PKU*/ | 0 /*OSPKE*/ | F(RDPID) |
F(AVX512_VPOPCNTDQ) | F(UMIP) | F(AVX512_VBMI2) | F(GFNI) |
F(VAES) | F(VPCLMULQDQ) | F(AVX512_VNNI) | F(AVX512_BITALG) |
F(CLDEMOTE) | F(MOVDIRI) | F(MOVDIR64B) | 0 /*WAITPKG*/;
/* cpuid 7.0.edx*/
const u32 kvm_cpuid_7_0_edx_x86_features =
F(AVX512_4VNNIW) | F(AVX512_4FMAPS) | F(SPEC_CTRL) |
F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES) | F(INTEL_STIBP) |
F(MD_CLEAR);
/* cpuid 7.1.eax */
const u32 kvm_cpuid_7_1_eax_x86_features =
F(AVX512_BF16);
switch (entry->index) {
case 0:
entry->eax = min(entry->eax, 1u);
entry->ebx &= kvm_cpuid_7_0_ebx_x86_features;
cpuid_entry_mask(entry, CPUID_7_0_EBX);
/* TSC_ADJUST is emulated */
cpuid_entry_set(entry, X86_FEATURE_TSC_ADJUST);
entry->ecx &= kvm_cpuid_7_0_ecx_x86_features;
f_la57 = cpuid_entry_get(entry, X86_FEATURE_LA57);
cpuid_entry_mask(entry, CPUID_7_ECX);
/* Set LA57 based on hardware capability. */
entry->ecx |= f_la57;
entry->edx &= kvm_cpuid_7_0_edx_x86_features;
cpuid_entry_mask(entry, CPUID_7_EDX);
if (boot_cpu_has(X86_FEATURE_IBPB) && boot_cpu_has(X86_FEATURE_IBRS))
cpuid_entry_set(entry, X86_FEATURE_SPEC_CTRL);
@ -387,7 +476,7 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry)
cpuid_entry_set(entry, X86_FEATURE_ARCH_CAPABILITIES);
break;
case 1:
entry->eax &= kvm_cpuid_7_1_eax_x86_features;
cpuid_entry_mask(entry, CPUID_7_1_EAX);
entry->ebx = 0;
entry->ecx = 0;
entry->edx = 0;
@ -406,72 +495,8 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
{
struct kvm_cpuid_entry2 *entry;
int r, i, max_idx;
unsigned f_nx = is_efer_nx() ? F(NX) : 0;
#ifdef CONFIG_X86_64
unsigned f_gbpages = F(GBPAGES);
unsigned f_lm = F(LM);
#else
unsigned f_gbpages = 0;
unsigned f_lm = 0;
#endif
unsigned f_intel_pt = kvm_x86_ops->pt_supported() ? F(INTEL_PT) : 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) |
F(TOPOEXT) | F(PERFCTR_CORE);
/* cpuid 0x80000008.ebx */
const u32 kvm_cpuid_8000_0008_ebx_x86_features =
F(CLZERO) | F(XSAVEERPTR) |
F(WBNOINVD) | F(AMD_IBPB) | F(AMD_IBRS) | F(AMD_SSBD) | F(VIRT_SSBD) |
F(AMD_SSB_NO) | F(AMD_STIBP) | F(AMD_STIBP_ALWAYS_ON);
/* 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 0xD.1.eax */
const u32 kvm_cpuid_D_1_eax_x86_features =
F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1) | F(XSAVES);
/* all calls to cpuid_count() should be made on the same cpu */
get_cpu();
@ -487,9 +512,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
entry->eax = min(entry->eax, 0x1fU);
break;
case 1:
entry->edx &= kvm_cpuid_1_edx_x86_features;
cpuid_entry_mask(entry, CPUID_1_EDX);
entry->ecx &= kvm_cpuid_1_ecx_x86_features;
cpuid_entry_mask(entry, CPUID_1_ECX);
/* we support x2apic emulation even if host does not support
* it since we emulate x2apic in software */
@ -599,7 +622,6 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
if (!entry)
goto out;
entry->eax &= kvm_cpuid_D_1_eax_x86_features;
cpuid_entry_mask(entry, CPUID_D_1_EAX);
if (!kvm_x86_ops->xsaves_supported())
@ -683,11 +705,10 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
entry->eax = min(entry->eax, 0x8000001f);
break;
case 0x80000001:
entry->edx &= kvm_cpuid_8000_0001_edx_x86_features;
cpuid_entry_mask(entry, CPUID_8000_0001_EDX);
/* Add it manually because it may not be in host CPUID. */
if (!tdp_enabled)
cpuid_entry_set(entry, X86_FEATURE_GBPAGES);
entry->ecx &= kvm_cpuid_8000_0001_ecx_x86_features;
cpuid_entry_mask(entry, CPUID_8000_0001_ECX);
break;
case 0x80000007: /* Advanced power management */
@ -706,7 +727,6 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
g_phys_as = phys_as;
entry->eax = g_phys_as | (virt_as << 8);
entry->edx = 0;
entry->ebx &= kvm_cpuid_8000_0008_ebx_x86_features;
cpuid_entry_mask(entry, CPUID_8000_0008_EBX);
/*
* AMD has separate bits for each SPEC_CTRL bit.
@ -749,7 +769,6 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
entry->eax = min(entry->eax, 0xC0000004);
break;
case 0xC0000001:
entry->edx &= kvm_cpuid_C000_0001_edx_x86_features;
cpuid_entry_mask(entry, CPUID_C000_0001_EDX);
break;
case 3: /* Processor serial number */

22
arch/x86/kvm/cpuid.h
View File

@ -6,6 +6,9 @@
#include <asm/cpu.h>
#include <asm/processor.h>
extern u32 kvm_cpu_caps[NCAPINTS] __read_mostly;
void kvm_set_cpu_caps(void);
int kvm_update_cpuid(struct kvm_vcpu *vcpu);
struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct kvm_vcpu *vcpu,
u32 function, u32 index);
@ -172,7 +175,8 @@ static __always_inline void cpuid_entry_mask(struct kvm_cpuid_entry2 *entry,
{
u32 *reg = cpuid_entry_get_reg(entry, leaf * 32);
*reg &= boot_cpu_data.x86_capability[leaf];
BUILD_BUG_ON(leaf >= ARRAY_SIZE(kvm_cpu_caps));
*reg &= kvm_cpu_caps[leaf];
}
static __always_inline u32 *guest_cpuid_get_register(struct kvm_vcpu *vcpu,
@ -262,4 +266,20 @@ static inline bool cpuid_fault_enabled(struct kvm_vcpu *vcpu)
MSR_MISC_FEATURES_ENABLES_CPUID_FAULT;
}
static __always_inline void kvm_cpu_cap_clear(unsigned int x86_feature)
{
unsigned int x86_leaf = x86_feature / 32;
reverse_cpuid_check(x86_leaf);
kvm_cpu_caps[x86_leaf] &= ~__feature_bit(x86_feature);
}
static __always_inline void kvm_cpu_cap_set(unsigned int x86_feature)
{
unsigned int x86_leaf = x86_feature / 32;
reverse_cpuid_check(x86_leaf);
kvm_cpu_caps[x86_leaf] |= __feature_bit(x86_feature);
}
#endif

2
arch/x86/kvm/svm.c
View File

@ -1479,6 +1479,8 @@ static __init int svm_hardware_setup(void)
pr_info("Virtual GIF supported\n");
}
kvm_set_cpu_caps();
return 0;
err:

2
arch/x86/kvm/vmx/vmx.c
View File

@ -7818,6 +7818,8 @@ static __init int hardware_setup(void)
return r;
}
kvm_set_cpu_caps();
r = alloc_kvm_area();
if (r)
nested_vmx_hardware_unsetup();