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KVM: x86: Move reverse CPUID helpers to separate header file
Split out the reverse CPUID machinery to a dedicated header file so that KVM selftests can reuse the reverse CPUID definitions without introducing any '#ifdef __KERNEL__' pollution. Co-developed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Ricardo Koller <ricarkol@google.com> Message-Id: <20210422005626.564163-2-ricarkol@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Ricardo Koller
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Paolo Bonzini
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Apr 26, 2021
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,185 @@ | ||
| /* SPDX-License-Identifier: GPL-2.0 */ | ||
| #ifndef ARCH_X86_KVM_REVERSE_CPUID_H | ||
| #define ARCH_X86_KVM_REVERSE_CPUID_H | ||
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| #include <uapi/asm/kvm.h> | ||
| #include <asm/cpufeature.h> | ||
| #include <asm/cpufeatures.h> | ||
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| /* | ||
| * Hardware-defined CPUID leafs that are scattered in the kernel, but need to | ||
| * be directly used by KVM. Note, these word values conflict with the kernel's | ||
| * "bug" caps, but KVM doesn't use those. | ||
| */ | ||
| enum kvm_only_cpuid_leafs { | ||
| CPUID_12_EAX = NCAPINTS, | ||
| NR_KVM_CPU_CAPS, | ||
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| NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS, | ||
| }; | ||
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| #define KVM_X86_FEATURE(w, f) ((w)*32 + (f)) | ||
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| /* Intel-defined SGX sub-features, CPUID level 0x12 (EAX). */ | ||
| #define KVM_X86_FEATURE_SGX1 KVM_X86_FEATURE(CPUID_12_EAX, 0) | ||
| #define KVM_X86_FEATURE_SGX2 KVM_X86_FEATURE(CPUID_12_EAX, 1) | ||
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| struct cpuid_reg { | ||
| u32 function; | ||
| u32 index; | ||
| int reg; | ||
| }; | ||
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| static const struct cpuid_reg reverse_cpuid[] = { | ||
| [CPUID_1_EDX] = { 1, 0, CPUID_EDX}, | ||
| [CPUID_8000_0001_EDX] = {0x80000001, 0, CPUID_EDX}, | ||
| [CPUID_8086_0001_EDX] = {0x80860001, 0, CPUID_EDX}, | ||
| [CPUID_1_ECX] = { 1, 0, CPUID_ECX}, | ||
| [CPUID_C000_0001_EDX] = {0xc0000001, 0, CPUID_EDX}, | ||
| [CPUID_8000_0001_ECX] = {0x80000001, 0, CPUID_ECX}, | ||
| [CPUID_7_0_EBX] = { 7, 0, CPUID_EBX}, | ||
| [CPUID_D_1_EAX] = { 0xd, 1, CPUID_EAX}, | ||
| [CPUID_8000_0008_EBX] = {0x80000008, 0, CPUID_EBX}, | ||
| [CPUID_6_EAX] = { 6, 0, CPUID_EAX}, | ||
| [CPUID_8000_000A_EDX] = {0x8000000a, 0, CPUID_EDX}, | ||
| [CPUID_7_ECX] = { 7, 0, CPUID_ECX}, | ||
| [CPUID_8000_0007_EBX] = {0x80000007, 0, CPUID_EBX}, | ||
| [CPUID_7_EDX] = { 7, 0, CPUID_EDX}, | ||
| [CPUID_7_1_EAX] = { 7, 1, CPUID_EAX}, | ||
| [CPUID_12_EAX] = {0x00000012, 0, CPUID_EAX}, | ||
| }; | ||
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| /* | ||
| * Reverse CPUID and its derivatives can only be used for hardware-defined | ||
| * feature words, i.e. words whose bits directly correspond to a CPUID leaf. | ||
| * Retrieving a feature bit or masking guest CPUID from a Linux-defined word | ||
| * is nonsensical as the bit number/mask is an arbitrary software-defined value | ||
| * and can't be used by KVM to query/control guest capabilities. And obviously | ||
| * the leaf being queried must have an entry in the lookup table. | ||
| */ | ||
| static __always_inline void reverse_cpuid_check(unsigned int x86_leaf) | ||
| { | ||
| BUILD_BUG_ON(x86_leaf == CPUID_LNX_1); | ||
| BUILD_BUG_ON(x86_leaf == CPUID_LNX_2); | ||
| BUILD_BUG_ON(x86_leaf == CPUID_LNX_3); | ||
| BUILD_BUG_ON(x86_leaf == CPUID_LNX_4); | ||
| BUILD_BUG_ON(x86_leaf >= ARRAY_SIZE(reverse_cpuid)); | ||
| BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0); | ||
| } | ||
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| /* | ||
| * Translate feature bits that are scattered in the kernel's cpufeatures word | ||
| * into KVM feature words that align with hardware's definitions. | ||
| */ | ||
| static __always_inline u32 __feature_translate(int x86_feature) | ||
| { | ||
| if (x86_feature == X86_FEATURE_SGX1) | ||
| return KVM_X86_FEATURE_SGX1; | ||
| else if (x86_feature == X86_FEATURE_SGX2) | ||
| return KVM_X86_FEATURE_SGX2; | ||
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| return x86_feature; | ||
| } | ||
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| static __always_inline u32 __feature_leaf(int x86_feature) | ||
| { | ||
| return __feature_translate(x86_feature) / 32; | ||
| } | ||
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| /* | ||
| * Retrieve the bit mask from an X86_FEATURE_* definition. Features contain | ||
| * the hardware defined bit number (stored in bits 4:0) and a software defined | ||
| * "word" (stored in bits 31:5). The word is used to index into arrays of | ||
| * bit masks that hold the per-cpu feature capabilities, e.g. this_cpu_has(). | ||
| */ | ||
| static __always_inline u32 __feature_bit(int x86_feature) | ||
| { | ||
| x86_feature = __feature_translate(x86_feature); | ||
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| reverse_cpuid_check(x86_feature / 32); | ||
| return 1 << (x86_feature & 31); | ||
| } | ||
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| #define feature_bit(name) __feature_bit(X86_FEATURE_##name) | ||
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| static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned int x86_feature) | ||
| { | ||
| unsigned int x86_leaf = __feature_leaf(x86_feature); | ||
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| reverse_cpuid_check(x86_leaf); | ||
| return reverse_cpuid[x86_leaf]; | ||
| } | ||
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| static __always_inline u32 *__cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry, | ||
| u32 reg) | ||
| { | ||
| switch (reg) { | ||
| case CPUID_EAX: | ||
| return &entry->eax; | ||
| case CPUID_EBX: | ||
| return &entry->ebx; | ||
| case CPUID_ECX: | ||
| return &entry->ecx; | ||
| case CPUID_EDX: | ||
| return &entry->edx; | ||
| default: | ||
| BUILD_BUG(); | ||
| return NULL; | ||
| } | ||
| } | ||
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| static __always_inline u32 *cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry, | ||
| unsigned int x86_feature) | ||
| { | ||
| const struct cpuid_reg cpuid = x86_feature_cpuid(x86_feature); | ||
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| return __cpuid_entry_get_reg(entry, cpuid.reg); | ||
| } | ||
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| static __always_inline u32 cpuid_entry_get(struct kvm_cpuid_entry2 *entry, | ||
| unsigned int x86_feature) | ||
| { | ||
| u32 *reg = cpuid_entry_get_reg(entry, x86_feature); | ||
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| return *reg & __feature_bit(x86_feature); | ||
| } | ||
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| static __always_inline bool cpuid_entry_has(struct kvm_cpuid_entry2 *entry, | ||
| unsigned int x86_feature) | ||
| { | ||
| return cpuid_entry_get(entry, x86_feature); | ||
| } | ||
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| static __always_inline void cpuid_entry_clear(struct kvm_cpuid_entry2 *entry, | ||
| unsigned int x86_feature) | ||
| { | ||
| u32 *reg = cpuid_entry_get_reg(entry, x86_feature); | ||
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| *reg &= ~__feature_bit(x86_feature); | ||
| } | ||
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| static __always_inline void cpuid_entry_set(struct kvm_cpuid_entry2 *entry, | ||
| unsigned int x86_feature) | ||
| { | ||
| u32 *reg = cpuid_entry_get_reg(entry, x86_feature); | ||
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| *reg |= __feature_bit(x86_feature); | ||
| } | ||
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| static __always_inline void cpuid_entry_change(struct kvm_cpuid_entry2 *entry, | ||
| unsigned int x86_feature, | ||
| bool set) | ||
| { | ||
| u32 *reg = cpuid_entry_get_reg(entry, x86_feature); | ||
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| /* | ||
| * Open coded instead of using cpuid_entry_{clear,set}() to coerce the | ||
| * compiler into using CMOV instead of Jcc when possible. | ||
| */ | ||
| if (set) | ||
| *reg |= __feature_bit(x86_feature); | ||
| else | ||
| *reg &= ~__feature_bit(x86_feature); | ||
| } | ||
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| #endif /* ARCH_X86_KVM_REVERSE_CPUID_H */ |