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 }; 72 73 /* 74 * Reverse CPUID and its derivatives can only be used for hardware-defined 75 * feature words, i.e. words whose bits directly correspond to a CPUID leaf. 76 * Retrieving a feature bit or masking guest CPUID from a Linux-defined word 77 * is nonsensical as the bit number/mask is an arbitrary software-defined value 78 * and can't be used by KVM to query/control guest capabilities. And obviously 79 * the leaf being queried must have an entry in the lookup table. 80 */ 81 static __always_inline void reverse_cpuid_check(unsigned int x86_leaf) 82 { 83 BUILD_BUG_ON(x86_leaf == CPUID_LNX_1); 84 BUILD_BUG_ON(x86_leaf == CPUID_LNX_2); 85 BUILD_BUG_ON(x86_leaf == CPUID_LNX_3); 86 BUILD_BUG_ON(x86_leaf == CPUID_LNX_4); 87 BUILD_BUG_ON(x86_leaf >= ARRAY_SIZE(reverse_cpuid)); 88 BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0); 89 } 90 91 /* 92 * Translate feature bits that are scattered in the kernel's cpufeatures word 93 * into KVM feature words that align with hardware's definitions. 94 */ 95 static __always_inline u32 __feature_translate(int x86_feature) 96 { 97 if (x86_feature == X86_FEATURE_SGX1) 98 return KVM_X86_FEATURE_SGX1; 99 else if (x86_feature == X86_FEATURE_SGX2) 100 return KVM_X86_FEATURE_SGX2; 101 else if (x86_feature == X86_FEATURE_SGX_EDECCSSA) 102 return KVM_X86_FEATURE_SGX_EDECCSSA; 103 104 return x86_feature; 105 } 106 107 static __always_inline u32 __feature_leaf(int x86_feature) 108 { 109 return __feature_translate(x86_feature) / 32; 110 } 111 112 /* 113 * Retrieve the bit mask from an X86_FEATURE_* definition. Features contain 114 * the hardware defined bit number (stored in bits 4:0) and a software defined 115 * "word" (stored in bits 31:5). The word is used to index into arrays of 116 * bit masks that hold the per-cpu feature capabilities, e.g. this_cpu_has(). 117 */ 118 static __always_inline u32 __feature_bit(int x86_feature) 119 { 120 x86_feature = __feature_translate(x86_feature); 121 122 reverse_cpuid_check(x86_feature / 32); 123 return 1 << (x86_feature & 31); 124 } 125 126 #define feature_bit(name) __feature_bit(X86_FEATURE_##name) 127 128 static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned int x86_feature) 129 { 130 unsigned int x86_leaf = __feature_leaf(x86_feature); 131 132 reverse_cpuid_check(x86_leaf); 133 return reverse_cpuid[x86_leaf]; 134 } 135 136 static __always_inline u32 *__cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry, 137 u32 reg) 138 { 139 switch (reg) { 140 case CPUID_EAX: 141 return &entry->eax; 142 case CPUID_EBX: 143 return &entry->ebx; 144 case CPUID_ECX: 145 return &entry->ecx; 146 case CPUID_EDX: 147 return &entry->edx; 148 default: 149 BUILD_BUG(); 150 return NULL; 151 } 152 } 153 154 static __always_inline u32 *cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry, 155 unsigned int x86_feature) 156 { 157 const struct cpuid_reg cpuid = x86_feature_cpuid(x86_feature); 158 159 return __cpuid_entry_get_reg(entry, cpuid.reg); 160 } 161 162 static __always_inline u32 cpuid_entry_get(struct kvm_cpuid_entry2 *entry, 163 unsigned int x86_feature) 164 { 165 u32 *reg = cpuid_entry_get_reg(entry, x86_feature); 166 167 return *reg & __feature_bit(x86_feature); 168 } 169 170 static __always_inline bool cpuid_entry_has(struct kvm_cpuid_entry2 *entry, 171 unsigned int x86_feature) 172 { 173 return cpuid_entry_get(entry, x86_feature); 174 } 175 176 static __always_inline void cpuid_entry_clear(struct kvm_cpuid_entry2 *entry, 177 unsigned int x86_feature) 178 { 179 u32 *reg = cpuid_entry_get_reg(entry, x86_feature); 180 181 *reg &= ~__feature_bit(x86_feature); 182 } 183 184 static __always_inline void cpuid_entry_set(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_change(struct kvm_cpuid_entry2 *entry, 193 unsigned int x86_feature, 194 bool set) 195 { 196 u32 *reg = cpuid_entry_get_reg(entry, x86_feature); 197 198 /* 199 * Open coded instead of using cpuid_entry_{clear,set}() to coerce the 200 * compiler into using CMOV instead of Jcc when possible. 201 */ 202 if (set) 203 *reg |= __feature_bit(x86_feature); 204 else 205 *reg &= ~__feature_bit(x86_feature); 206 } 207 208 #endif /* ARCH_X86_KVM_REVERSE_CPUID_H */ 209