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 either scattered by the kernel or are 11 * unknown to the kernel, but need to be directly used by KVM. Note, these 12 * word values conflict with the kernel's "bug" caps, but KVM doesn't use those. 13 */ 14 enum kvm_only_cpuid_leafs { 15 CPUID_12_EAX = NCAPINTS, 16 CPUID_7_1_EDX, 17 CPUID_8000_0007_EDX, 18 NR_KVM_CPU_CAPS, 19 20 NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS, 21 }; 22 23 /* 24 * Define a KVM-only feature flag. 25 * 26 * For features that are scattered by cpufeatures.h, __feature_translate() also 27 * needs to be updated to translate the kernel-defined feature into the 28 * KVM-defined feature. 29 * 30 * For features that are 100% KVM-only, i.e. not defined by cpufeatures.h, 31 * forego the intermediate KVM_X86_FEATURE and directly define X86_FEATURE_* so 32 * that X86_FEATURE_* can be used in KVM. No __feature_translate() handling is 33 * needed in this case. 34 */ 35 #define KVM_X86_FEATURE(w, f) ((w)*32 + (f)) 36 37 /* Intel-defined SGX sub-features, CPUID level 0x12 (EAX). */ 38 #define KVM_X86_FEATURE_SGX1 KVM_X86_FEATURE(CPUID_12_EAX, 0) 39 #define KVM_X86_FEATURE_SGX2 KVM_X86_FEATURE(CPUID_12_EAX, 1) 40 #define KVM_X86_FEATURE_SGX_EDECCSSA KVM_X86_FEATURE(CPUID_12_EAX, 11) 41 42 /* Intel-defined sub-features, CPUID level 0x00000007:1 (EDX) */ 43 #define X86_FEATURE_AVX_VNNI_INT8 KVM_X86_FEATURE(CPUID_7_1_EDX, 4) 44 #define X86_FEATURE_AVX_NE_CONVERT KVM_X86_FEATURE(CPUID_7_1_EDX, 5) 45 #define X86_FEATURE_PREFETCHITI KVM_X86_FEATURE(CPUID_7_1_EDX, 14) 46 47 /* CPUID level 0x80000007 (EDX). */ 48 #define KVM_X86_FEATURE_CONSTANT_TSC KVM_X86_FEATURE(CPUID_8000_0007_EDX, 8) 49 50 struct cpuid_reg { 51 u32 function; 52 u32 index; 53 int reg; 54 }; 55 56 static const struct cpuid_reg reverse_cpuid[] = { 57 [CPUID_1_EDX] = { 1, 0, CPUID_EDX}, 58 [CPUID_8000_0001_EDX] = {0x80000001, 0, CPUID_EDX}, 59 [CPUID_8086_0001_EDX] = {0x80860001, 0, CPUID_EDX}, 60 [CPUID_1_ECX] = { 1, 0, CPUID_ECX}, 61 [CPUID_C000_0001_EDX] = {0xc0000001, 0, CPUID_EDX}, 62 [CPUID_8000_0001_ECX] = {0x80000001, 0, CPUID_ECX}, 63 [CPUID_7_0_EBX] = { 7, 0, CPUID_EBX}, 64 [CPUID_D_1_EAX] = { 0xd, 1, CPUID_EAX}, 65 [CPUID_8000_0008_EBX] = {0x80000008, 0, CPUID_EBX}, 66 [CPUID_6_EAX] = { 6, 0, CPUID_EAX}, 67 [CPUID_8000_000A_EDX] = {0x8000000a, 0, CPUID_EDX}, 68 [CPUID_7_ECX] = { 7, 0, CPUID_ECX}, 69 [CPUID_8000_0007_EBX] = {0x80000007, 0, CPUID_EBX}, 70 [CPUID_7_EDX] = { 7, 0, CPUID_EDX}, 71 [CPUID_7_1_EAX] = { 7, 1, CPUID_EAX}, 72 [CPUID_12_EAX] = {0x00000012, 0, CPUID_EAX}, 73 [CPUID_8000_001F_EAX] = {0x8000001f, 0, CPUID_EAX}, 74 [CPUID_7_1_EDX] = { 7, 1, CPUID_EDX}, 75 [CPUID_8000_0007_EDX] = {0x80000007, 0, CPUID_EDX}, 76 [CPUID_8000_0021_EAX] = {0x80000021, 0, CPUID_EAX}, 77 }; 78 79 /* 80 * Reverse CPUID and its derivatives can only be used for hardware-defined 81 * feature words, i.e. words whose bits directly correspond to a CPUID leaf. 82 * Retrieving a feature bit or masking guest CPUID from a Linux-defined word 83 * is nonsensical as the bit number/mask is an arbitrary software-defined value 84 * and can't be used by KVM to query/control guest capabilities. And obviously 85 * the leaf being queried must have an entry in the lookup table. 86 */ 87 static __always_inline void reverse_cpuid_check(unsigned int x86_leaf) 88 { 89 BUILD_BUG_ON(x86_leaf == CPUID_LNX_1); 90 BUILD_BUG_ON(x86_leaf == CPUID_LNX_2); 91 BUILD_BUG_ON(x86_leaf == CPUID_LNX_3); 92 BUILD_BUG_ON(x86_leaf == CPUID_LNX_4); 93 BUILD_BUG_ON(x86_leaf >= ARRAY_SIZE(reverse_cpuid)); 94 BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0); 95 } 96 97 /* 98 * Translate feature bits that are scattered in the kernel's cpufeatures word 99 * into KVM feature words that align with hardware's definitions. 100 */ 101 static __always_inline u32 __feature_translate(int x86_feature) 102 { 103 if (x86_feature == X86_FEATURE_SGX1) 104 return KVM_X86_FEATURE_SGX1; 105 else if (x86_feature == X86_FEATURE_SGX2) 106 return KVM_X86_FEATURE_SGX2; 107 else if (x86_feature == X86_FEATURE_SGX_EDECCSSA) 108 return KVM_X86_FEATURE_SGX_EDECCSSA; 109 else if (x86_feature == X86_FEATURE_CONSTANT_TSC) 110 return KVM_X86_FEATURE_CONSTANT_TSC; 111 112 return x86_feature; 113 } 114 115 static __always_inline u32 __feature_leaf(int x86_feature) 116 { 117 return __feature_translate(x86_feature) / 32; 118 } 119 120 /* 121 * Retrieve the bit mask from an X86_FEATURE_* definition. Features contain 122 * the hardware defined bit number (stored in bits 4:0) and a software defined 123 * "word" (stored in bits 31:5). The word is used to index into arrays of 124 * bit masks that hold the per-cpu feature capabilities, e.g. this_cpu_has(). 125 */ 126 static __always_inline u32 __feature_bit(int x86_feature) 127 { 128 x86_feature = __feature_translate(x86_feature); 129 130 reverse_cpuid_check(x86_feature / 32); 131 return 1 << (x86_feature & 31); 132 } 133 134 #define feature_bit(name) __feature_bit(X86_FEATURE_##name) 135 136 static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned int x86_feature) 137 { 138 unsigned int x86_leaf = __feature_leaf(x86_feature); 139 140 reverse_cpuid_check(x86_leaf); 141 return reverse_cpuid[x86_leaf]; 142 } 143 144 static __always_inline u32 *__cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry, 145 u32 reg) 146 { 147 switch (reg) { 148 case CPUID_EAX: 149 return &entry->eax; 150 case CPUID_EBX: 151 return &entry->ebx; 152 case CPUID_ECX: 153 return &entry->ecx; 154 case CPUID_EDX: 155 return &entry->edx; 156 default: 157 BUILD_BUG(); 158 return NULL; 159 } 160 } 161 162 static __always_inline u32 *cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry, 163 unsigned int x86_feature) 164 { 165 const struct cpuid_reg cpuid = x86_feature_cpuid(x86_feature); 166 167 return __cpuid_entry_get_reg(entry, cpuid.reg); 168 } 169 170 static __always_inline u32 cpuid_entry_get(struct kvm_cpuid_entry2 *entry, 171 unsigned int x86_feature) 172 { 173 u32 *reg = cpuid_entry_get_reg(entry, x86_feature); 174 175 return *reg & __feature_bit(x86_feature); 176 } 177 178 static __always_inline bool cpuid_entry_has(struct kvm_cpuid_entry2 *entry, 179 unsigned int x86_feature) 180 { 181 return cpuid_entry_get(entry, x86_feature); 182 } 183 184 static __always_inline void cpuid_entry_clear(struct kvm_cpuid_entry2 *entry, 185 unsigned int x86_feature) 186 { 187 u32 *reg = cpuid_entry_get_reg(entry, x86_feature); 188 189 *reg &= ~__feature_bit(x86_feature); 190 } 191 192 static __always_inline void cpuid_entry_set(struct kvm_cpuid_entry2 *entry, 193 unsigned int x86_feature) 194 { 195 u32 *reg = cpuid_entry_get_reg(entry, x86_feature); 196 197 *reg |= __feature_bit(x86_feature); 198 } 199 200 static __always_inline void cpuid_entry_change(struct kvm_cpuid_entry2 *entry, 201 unsigned int x86_feature, 202 bool set) 203 { 204 u32 *reg = cpuid_entry_get_reg(entry, x86_feature); 205 206 /* 207 * Open coded instead of using cpuid_entry_{clear,set}() to coerce the 208 * compiler into using CMOV instead of Jcc when possible. 209 */ 210 if (set) 211 *reg |= __feature_bit(x86_feature); 212 else 213 *reg &= ~__feature_bit(x86_feature); 214 } 215 216 #endif /* ARCH_X86_KVM_REVERSE_CPUID_H */ 217