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