1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef ARCH_X86_KVM_REVERSE_CPUID_H 3 #define ARCH_X86_KVM_REVERSE_CPUID_H 4 5 #include <uapi/asm/kvm.h> 6 #include <asm/cpufeature.h> 7 #include <asm/cpufeatures.h> 8 9 /* 10 * Hardware-defined CPUID leafs that are scattered in the kernel, but need to 11 * be directly used by KVM. Note, these word values conflict with the kernel's 12 * "bug" caps, but KVM doesn't use those. 13 */ 14 enum kvm_only_cpuid_leafs { 15 CPUID_12_EAX = NCAPINTS, 16 NR_KVM_CPU_CAPS, 17 18 NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS, 19 }; 20 21 #define KVM_X86_FEATURE(w, f) ((w)*32 + (f)) 22 23 /* Intel-defined SGX sub-features, CPUID level 0x12 (EAX). */ 24 #define KVM_X86_FEATURE_SGX1 KVM_X86_FEATURE(CPUID_12_EAX, 0) 25 #define KVM_X86_FEATURE_SGX2 KVM_X86_FEATURE(CPUID_12_EAX, 1) 26 #define KVM_X86_FEATURE_SGX_EDECCSSA KVM_X86_FEATURE(CPUID_12_EAX, 11) 27 28 struct cpuid_reg { 29 u32 function; 30 u32 index; 31 int reg; 32 }; 33 34 static const struct cpuid_reg reverse_cpuid[] = { 35 [CPUID_1_EDX] = { 1, 0, CPUID_EDX}, 36 [CPUID_8000_0001_EDX] = {0x80000001, 0, CPUID_EDX}, 37 [CPUID_8086_0001_EDX] = {0x80860001, 0, CPUID_EDX}, 38 [CPUID_1_ECX] = { 1, 0, CPUID_ECX}, 39 [CPUID_C000_0001_EDX] = {0xc0000001, 0, CPUID_EDX}, 40 [CPUID_8000_0001_ECX] = {0x80000001, 0, CPUID_ECX}, 41 [CPUID_7_0_EBX] = { 7, 0, CPUID_EBX}, 42 [CPUID_D_1_EAX] = { 0xd, 1, CPUID_EAX}, 43 [CPUID_8000_0008_EBX] = {0x80000008, 0, CPUID_EBX}, 44 [CPUID_6_EAX] = { 6, 0, CPUID_EAX}, 45 [CPUID_8000_000A_EDX] = {0x8000000a, 0, CPUID_EDX}, 46 [CPUID_7_ECX] = { 7, 0, CPUID_ECX}, 47 [CPUID_8000_0007_EBX] = {0x80000007, 0, CPUID_EBX}, 48 [CPUID_7_EDX] = { 7, 0, CPUID_EDX}, 49 [CPUID_7_1_EAX] = { 7, 1, CPUID_EAX}, 50 [CPUID_12_EAX] = {0x00000012, 0, CPUID_EAX}, 51 [CPUID_8000_001F_EAX] = {0x8000001f, 0, CPUID_EAX}, 52 }; 53 54 /* 55 * Reverse CPUID and its derivatives can only be used for hardware-defined 56 * feature words, i.e. words whose bits directly correspond to a CPUID leaf. 57 * Retrieving a feature bit or masking guest CPUID from a Linux-defined word 58 * is nonsensical as the bit number/mask is an arbitrary software-defined value 59 * and can't be used by KVM to query/control guest capabilities. And obviously 60 * the leaf being queried must have an entry in the lookup table. 61 */ 62 static __always_inline void reverse_cpuid_check(unsigned int x86_leaf) 63 { 64 BUILD_BUG_ON(x86_leaf == CPUID_LNX_1); 65 BUILD_BUG_ON(x86_leaf == CPUID_LNX_2); 66 BUILD_BUG_ON(x86_leaf == CPUID_LNX_3); 67 BUILD_BUG_ON(x86_leaf == CPUID_LNX_4); 68 BUILD_BUG_ON(x86_leaf >= ARRAY_SIZE(reverse_cpuid)); 69 BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0); 70 } 71 72 /* 73 * Translate feature bits that are scattered in the kernel's cpufeatures word 74 * into KVM feature words that align with hardware's definitions. 75 */ 76 static __always_inline u32 __feature_translate(int x86_feature) 77 { 78 if (x86_feature == X86_FEATURE_SGX1) 79 return KVM_X86_FEATURE_SGX1; 80 else if (x86_feature == X86_FEATURE_SGX2) 81 return KVM_X86_FEATURE_SGX2; 82 else if (x86_feature == X86_FEATURE_SGX_EDECCSSA) 83 return KVM_X86_FEATURE_SGX_EDECCSSA; 84 85 return x86_feature; 86 } 87 88 static __always_inline u32 __feature_leaf(int x86_feature) 89 { 90 return __feature_translate(x86_feature) / 32; 91 } 92 93 /* 94 * Retrieve the bit mask from an X86_FEATURE_* definition. Features contain 95 * the hardware defined bit number (stored in bits 4:0) and a software defined 96 * "word" (stored in bits 31:5). The word is used to index into arrays of 97 * bit masks that hold the per-cpu feature capabilities, e.g. this_cpu_has(). 98 */ 99 static __always_inline u32 __feature_bit(int x86_feature) 100 { 101 x86_feature = __feature_translate(x86_feature); 102 103 reverse_cpuid_check(x86_feature / 32); 104 return 1 << (x86_feature & 31); 105 } 106 107 #define feature_bit(name) __feature_bit(X86_FEATURE_##name) 108 109 static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned int x86_feature) 110 { 111 unsigned int x86_leaf = __feature_leaf(x86_feature); 112 113 reverse_cpuid_check(x86_leaf); 114 return reverse_cpuid[x86_leaf]; 115 } 116 117 static __always_inline u32 *__cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry, 118 u32 reg) 119 { 120 switch (reg) { 121 case CPUID_EAX: 122 return &entry->eax; 123 case CPUID_EBX: 124 return &entry->ebx; 125 case CPUID_ECX: 126 return &entry->ecx; 127 case CPUID_EDX: 128 return &entry->edx; 129 default: 130 BUILD_BUG(); 131 return NULL; 132 } 133 } 134 135 static __always_inline u32 *cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry, 136 unsigned int x86_feature) 137 { 138 const struct cpuid_reg cpuid = x86_feature_cpuid(x86_feature); 139 140 return __cpuid_entry_get_reg(entry, cpuid.reg); 141 } 142 143 static __always_inline u32 cpuid_entry_get(struct kvm_cpuid_entry2 *entry, 144 unsigned int x86_feature) 145 { 146 u32 *reg = cpuid_entry_get_reg(entry, x86_feature); 147 148 return *reg & __feature_bit(x86_feature); 149 } 150 151 static __always_inline bool cpuid_entry_has(struct kvm_cpuid_entry2 *entry, 152 unsigned int x86_feature) 153 { 154 return cpuid_entry_get(entry, x86_feature); 155 } 156 157 static __always_inline void cpuid_entry_clear(struct kvm_cpuid_entry2 *entry, 158 unsigned int x86_feature) 159 { 160 u32 *reg = cpuid_entry_get_reg(entry, x86_feature); 161 162 *reg &= ~__feature_bit(x86_feature); 163 } 164 165 static __always_inline void cpuid_entry_set(struct kvm_cpuid_entry2 *entry, 166 unsigned int x86_feature) 167 { 168 u32 *reg = cpuid_entry_get_reg(entry, x86_feature); 169 170 *reg |= __feature_bit(x86_feature); 171 } 172 173 static __always_inline void cpuid_entry_change(struct kvm_cpuid_entry2 *entry, 174 unsigned int x86_feature, 175 bool set) 176 { 177 u32 *reg = cpuid_entry_get_reg(entry, x86_feature); 178 179 /* 180 * Open coded instead of using cpuid_entry_{clear,set}() to coerce the 181 * compiler into using CMOV instead of Jcc when possible. 182 */ 183 if (set) 184 *reg |= __feature_bit(x86_feature); 185 else 186 *reg &= ~__feature_bit(x86_feature); 187 } 188 189 #endif /* ARCH_X86_KVM_REVERSE_CPUID_H */ 190