arch/x86/kvm/reverse_cpuid.h

   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         CPUID_8000_0022_EAX,
  19         CPUID_7_2_EDX,
  20         CPUID_24_0_EBX,
  21         NR_KVM_CPU_CAPS,
  22
  23         NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS,
  24 };
  25
  26 /*
  27  * Define a KVM-only feature flag.
  28  *
  29  * For features that are scattered by cpufeatures.h, __feature_translate() also
  30  * needs to be updated to translate the kernel-defined feature into the
  31  * KVM-defined feature.
  32  *
  33  * For features that are 100% KVM-only, i.e. not defined by cpufeatures.h,
  34  * forego the intermediate KVM_X86_FEATURE and directly define X86_FEATURE_* so
  35  * that X86_FEATURE_* can be used in KVM.  No __feature_translate() handling is
  36  * needed in this case.
  37  */
  38 #define KVM_X86_FEATURE(w, f)           ((w)*32 + (f))
  39
  40 /* Intel-defined SGX sub-features, CPUID level 0x12 (EAX). */
  41 #define KVM_X86_FEATURE_SGX1            KVM_X86_FEATURE(CPUID_12_EAX, 0)
  42 #define KVM_X86_FEATURE_SGX2            KVM_X86_FEATURE(CPUID_12_EAX, 1)
  43 #define KVM_X86_FEATURE_SGX_EDECCSSA    KVM_X86_FEATURE(CPUID_12_EAX, 11)
  44
  45 /* Intel-defined sub-features, CPUID level 0x00000007:1 (EDX) */
  46 #define X86_FEATURE_AVX_VNNI_INT8       KVM_X86_FEATURE(CPUID_7_1_EDX, 4)
  47 #define X86_FEATURE_AVX_NE_CONVERT      KVM_X86_FEATURE(CPUID_7_1_EDX, 5)
  48 #define X86_FEATURE_AMX_COMPLEX         KVM_X86_FEATURE(CPUID_7_1_EDX, 8)
  49 #define X86_FEATURE_PREFETCHITI         KVM_X86_FEATURE(CPUID_7_1_EDX, 14)
  50 #define X86_FEATURE_AVX10               KVM_X86_FEATURE(CPUID_7_1_EDX, 19)
  51
  52 /* Intel-defined sub-features, CPUID level 0x00000007:2 (EDX) */
  53 #define X86_FEATURE_INTEL_PSFD          KVM_X86_FEATURE(CPUID_7_2_EDX, 0)
  54 #define X86_FEATURE_IPRED_CTRL          KVM_X86_FEATURE(CPUID_7_2_EDX, 1)
  55 #define KVM_X86_FEATURE_RRSBA_CTRL      KVM_X86_FEATURE(CPUID_7_2_EDX, 2)
  56 #define X86_FEATURE_DDPD_U              KVM_X86_FEATURE(CPUID_7_2_EDX, 3)
  57 #define KVM_X86_FEATURE_BHI_CTRL        KVM_X86_FEATURE(CPUID_7_2_EDX, 4)
  58 #define X86_FEATURE_MCDT_NO             KVM_X86_FEATURE(CPUID_7_2_EDX, 5)
  59
  60 /* Intel-defined sub-features, CPUID level 0x00000024:0 (EBX) */
  61 #define X86_FEATURE_AVX10_128           KVM_X86_FEATURE(CPUID_24_0_EBX, 16)
  62 #define X86_FEATURE_AVX10_256           KVM_X86_FEATURE(CPUID_24_0_EBX, 17)
  63 #define X86_FEATURE_AVX10_512           KVM_X86_FEATURE(CPUID_24_0_EBX, 18)
  64
  65 /* CPUID level 0x80000007 (EDX). */
  66 #define KVM_X86_FEATURE_CONSTANT_TSC    KVM_X86_FEATURE(CPUID_8000_0007_EDX, 8)
  67
  68 /* CPUID level 0x80000022 (EAX) */
  69 #define KVM_X86_FEATURE_PERFMON_V2      KVM_X86_FEATURE(CPUID_8000_0022_EAX, 0)
  70
  71 struct cpuid_reg {
  72         u32 function;
  73         u32 index;
  74         int reg;
  75 };
  76
  77 static const struct cpuid_reg reverse_cpuid[] = {
  78         [CPUID_1_EDX]         = {         1, 0, CPUID_EDX},
  79         [CPUID_8000_0001_EDX] = {0x80000001, 0, CPUID_EDX},
  80         [CPUID_8086_0001_EDX] = {0x80860001, 0, CPUID_EDX},
  81         [CPUID_1_ECX]         = {         1, 0, CPUID_ECX},
  82         [CPUID_C000_0001_EDX] = {0xc0000001, 0, CPUID_EDX},
  83         [CPUID_8000_0001_ECX] = {0x80000001, 0, CPUID_ECX},
  84         [CPUID_7_0_EBX]       = {         7, 0, CPUID_EBX},
  85         [CPUID_D_1_EAX]       = {       0xd, 1, CPUID_EAX},
  86         [CPUID_8000_0008_EBX] = {0x80000008, 0, CPUID_EBX},
  87         [CPUID_6_EAX]         = {         6, 0, CPUID_EAX},
  88         [CPUID_8000_000A_EDX] = {0x8000000a, 0, CPUID_EDX},
  89         [CPUID_7_ECX]         = {         7, 0, CPUID_ECX},
  90         [CPUID_8000_0007_EBX] = {0x80000007, 0, CPUID_EBX},
  91         [CPUID_7_EDX]         = {         7, 0, CPUID_EDX},
  92         [CPUID_7_1_EAX]       = {         7, 1, CPUID_EAX},
  93         [CPUID_12_EAX]        = {0x00000012, 0, CPUID_EAX},
  94         [CPUID_8000_001F_EAX] = {0x8000001f, 0, CPUID_EAX},
  95         [CPUID_7_1_EDX]       = {         7, 1, CPUID_EDX},
  96         [CPUID_8000_0007_EDX] = {0x80000007, 0, CPUID_EDX},
  97         [CPUID_8000_0021_EAX] = {0x80000021, 0, CPUID_EAX},
  98         [CPUID_8000_0022_EAX] = {0x80000022, 0, CPUID_EAX},
  99         [CPUID_7_2_EDX]       = {         7, 2, CPUID_EDX},
 100         [CPUID_24_0_EBX]      = {      0x24, 0, CPUID_EBX},
 101 };
 102
 103 /*
 104  * Reverse CPUID and its derivatives can only be used for hardware-defined
 105  * feature words, i.e. words whose bits directly correspond to a CPUID leaf.
 106  * Retrieving a feature bit or masking guest CPUID from a Linux-defined word
 107  * is nonsensical as the bit number/mask is an arbitrary software-defined value
 108  * and can't be used by KVM to query/control guest capabilities.  And obviously
 109  * the leaf being queried must have an entry in the lookup table.
 110  */
 111 static __always_inline void reverse_cpuid_check(unsigned int x86_leaf)
 112 {
 113         BUILD_BUG_ON(NR_CPUID_WORDS != NCAPINTS);
 114         BUILD_BUG_ON(x86_leaf == CPUID_LNX_1);
 115         BUILD_BUG_ON(x86_leaf == CPUID_LNX_2);
 116         BUILD_BUG_ON(x86_leaf == CPUID_LNX_3);
 117         BUILD_BUG_ON(x86_leaf == CPUID_LNX_4);
 118         BUILD_BUG_ON(x86_leaf == CPUID_LNX_5);
 119         BUILD_BUG_ON(x86_leaf >= ARRAY_SIZE(reverse_cpuid));
 120         BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0);
 121 }
 122
 123 /*
 124  * Translate feature bits that are scattered in the kernel's cpufeatures word
 125  * into KVM feature words that align with hardware's definitions.
 126  */
 127 static __always_inline u32 __feature_translate(int x86_feature)
 128 {
 129 #define KVM_X86_TRANSLATE_FEATURE(f)    \
 130         case X86_FEATURE_##f: return KVM_X86_FEATURE_##f
 131
 132         switch (x86_feature) {
 133         KVM_X86_TRANSLATE_FEATURE(SGX1);
 134         KVM_X86_TRANSLATE_FEATURE(SGX2);
 135         KVM_X86_TRANSLATE_FEATURE(SGX_EDECCSSA);
 136         KVM_X86_TRANSLATE_FEATURE(CONSTANT_TSC);
 137         KVM_X86_TRANSLATE_FEATURE(PERFMON_V2);
 138         KVM_X86_TRANSLATE_FEATURE(RRSBA_CTRL);
 139         KVM_X86_TRANSLATE_FEATURE(BHI_CTRL);
 140         default:
 141                 return x86_feature;
 142         }
 143 }
 144
 145 static __always_inline u32 __feature_leaf(int x86_feature)
 146 {
 147         return __feature_translate(x86_feature) / 32;
 148 }
 149
 150 /*
 151  * Retrieve the bit mask from an X86_FEATURE_* definition.  Features contain
 152  * the hardware defined bit number (stored in bits 4:0) and a software defined
 153  * "word" (stored in bits 31:5).  The word is used to index into arrays of
 154  * bit masks that hold the per-cpu feature capabilities, e.g. this_cpu_has().
 155  */
 156 static __always_inline u32 __feature_bit(int x86_feature)
 157 {
 158         x86_feature = __feature_translate(x86_feature);
 159
 160         reverse_cpuid_check(x86_feature / 32);
 161         return 1 << (x86_feature & 31);
 162 }
 163
 164 #define feature_bit(name)  __feature_bit(X86_FEATURE_##name)
 165
 166 static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned int x86_feature)
 167 {
 168         unsigned int x86_leaf = __feature_leaf(x86_feature);
 169
 170         reverse_cpuid_check(x86_leaf);
 171         return reverse_cpuid[x86_leaf];
 172 }
 173
 174 static __always_inline u32 *__cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry,
 175                                                   u32 reg)
 176 {
 177         switch (reg) {
 178         case CPUID_EAX:
 179                 return &entry->eax;
 180         case CPUID_EBX:
 181                 return &entry->ebx;
 182         case CPUID_ECX:
 183                 return &entry->ecx;
 184         case CPUID_EDX:
 185                 return &entry->edx;
 186         default:
 187                 BUILD_BUG();
 188                 return NULL;
 189         }
 190 }
 191
 192 static __always_inline u32 *cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry,
 193                                                 unsigned int x86_feature)
 194 {
 195         const struct cpuid_reg cpuid = x86_feature_cpuid(x86_feature);
 196
 197         return __cpuid_entry_get_reg(entry, cpuid.reg);
 198 }
 199
 200 static __always_inline u32 cpuid_entry_get(struct kvm_cpuid_entry2 *entry,
 201                                            unsigned int x86_feature)
 202 {
 203         u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
 204
 205         return *reg & __feature_bit(x86_feature);
 206 }
 207
 208 static __always_inline bool cpuid_entry_has(struct kvm_cpuid_entry2 *entry,
 209                                             unsigned int x86_feature)
 210 {
 211         return cpuid_entry_get(entry, x86_feature);
 212 }
 213
 214 static __always_inline void cpuid_entry_clear(struct kvm_cpuid_entry2 *entry,
 215                                               unsigned int x86_feature)
 216 {
 217         u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
 218
 219         *reg &= ~__feature_bit(x86_feature);
 220 }
 221
 222 static __always_inline void cpuid_entry_set(struct kvm_cpuid_entry2 *entry,
 223                                             unsigned int x86_feature)
 224 {
 225         u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
 226
 227         *reg |= __feature_bit(x86_feature);
 228 }
 229
 230 static __always_inline void cpuid_entry_change(struct kvm_cpuid_entry2 *entry,
 231                                                unsigned int x86_feature,
 232                                                bool set)
 233 {
 234         u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
 235
 236         /*
 237          * Open coded instead of using cpuid_entry_{clear,set}() to coerce the
 238          * compiler into using CMOV instead of Jcc when possible.
 239          */
 240         if (set)
 241                 *reg |= __feature_bit(x86_feature);
 242         else
 243                 *reg &= ~__feature_bit(x86_feature);
 244 }
 245
 246 #endif /* ARCH_X86_KVM_REVERSE_CPUID_H */