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_AVX_VNNI_INT16      KVM_X86_FEATURE(CPUID_7_1_EDX, 10)
  50 #define X86_FEATURE_PREFETCHITI         KVM_X86_FEATURE(CPUID_7_1_EDX, 14)
  51 #define X86_FEATURE_AVX10               KVM_X86_FEATURE(CPUID_7_1_EDX, 19)
  52
  53 /* Intel-defined sub-features, CPUID level 0x00000007:2 (EDX) */
  54 #define X86_FEATURE_INTEL_PSFD          KVM_X86_FEATURE(CPUID_7_2_EDX, 0)
  55 #define X86_FEATURE_IPRED_CTRL          KVM_X86_FEATURE(CPUID_7_2_EDX, 1)
  56 #define KVM_X86_FEATURE_RRSBA_CTRL      KVM_X86_FEATURE(CPUID_7_2_EDX, 2)
  57 #define X86_FEATURE_DDPD_U              KVM_X86_FEATURE(CPUID_7_2_EDX, 3)
  58 #define KVM_X86_FEATURE_BHI_CTRL        KVM_X86_FEATURE(CPUID_7_2_EDX, 4)
  59 #define X86_FEATURE_MCDT_NO             KVM_X86_FEATURE(CPUID_7_2_EDX, 5)
  60
  61 /* Intel-defined sub-features, CPUID level 0x00000024:0 (EBX) */
  62 #define X86_FEATURE_AVX10_128           KVM_X86_FEATURE(CPUID_24_0_EBX, 16)
  63 #define X86_FEATURE_AVX10_256           KVM_X86_FEATURE(CPUID_24_0_EBX, 17)
  64 #define X86_FEATURE_AVX10_512           KVM_X86_FEATURE(CPUID_24_0_EBX, 18)
  65
  66 /* CPUID level 0x80000007 (EDX). */
  67 #define KVM_X86_FEATURE_CONSTANT_TSC    KVM_X86_FEATURE(CPUID_8000_0007_EDX, 8)
  68
  69 /* CPUID level 0x80000022 (EAX) */
  70 #define KVM_X86_FEATURE_PERFMON_V2      KVM_X86_FEATURE(CPUID_8000_0022_EAX, 0)
  71
  72 struct cpuid_reg {
  73         u32 function;
  74         u32 index;
  75         int reg;
  76 };
  77
  78 static const struct cpuid_reg reverse_cpuid[] = {
  79         [CPUID_1_EDX]         = {         1, 0, CPUID_EDX},
  80         [CPUID_8000_0001_EDX] = {0x80000001, 0, CPUID_EDX},
  81         [CPUID_8086_0001_EDX] = {0x80860001, 0, CPUID_EDX},
  82         [CPUID_1_ECX]         = {         1, 0, CPUID_ECX},
  83         [CPUID_C000_0001_EDX] = {0xc0000001, 0, CPUID_EDX},
  84         [CPUID_8000_0001_ECX] = {0x80000001, 0, CPUID_ECX},
  85         [CPUID_7_0_EBX]       = {         7, 0, CPUID_EBX},
  86         [CPUID_D_1_EAX]       = {       0xd, 1, CPUID_EAX},
  87         [CPUID_8000_0008_EBX] = {0x80000008, 0, CPUID_EBX},
  88         [CPUID_6_EAX]         = {         6, 0, CPUID_EAX},
  89         [CPUID_8000_000A_EDX] = {0x8000000a, 0, CPUID_EDX},
  90         [CPUID_7_ECX]         = {         7, 0, CPUID_ECX},
  91         [CPUID_8000_0007_EBX] = {0x80000007, 0, CPUID_EBX},
  92         [CPUID_7_EDX]         = {         7, 0, CPUID_EDX},
  93         [CPUID_7_1_EAX]       = {         7, 1, CPUID_EAX},
  94         [CPUID_12_EAX]        = {0x00000012, 0, CPUID_EAX},
  95         [CPUID_8000_001F_EAX] = {0x8000001f, 0, CPUID_EAX},
  96         [CPUID_7_1_EDX]       = {         7, 1, CPUID_EDX},
  97         [CPUID_8000_0007_EDX] = {0x80000007, 0, CPUID_EDX},
  98         [CPUID_8000_0021_EAX] = {0x80000021, 0, CPUID_EAX},
  99         [CPUID_8000_0022_EAX] = {0x80000022, 0, CPUID_EAX},
 100         [CPUID_7_2_EDX]       = {         7, 2, CPUID_EDX},
 101         [CPUID_24_0_EBX]      = {      0x24, 0, CPUID_EBX},
 102 };
 103
 104 /*
 105  * Reverse CPUID and its derivatives can only be used for hardware-defined
 106  * feature words, i.e. words whose bits directly correspond to a CPUID leaf.
 107  * Retrieving a feature bit or masking guest CPUID from a Linux-defined word
 108  * is nonsensical as the bit number/mask is an arbitrary software-defined value
 109  * and can't be used by KVM to query/control guest capabilities.  And obviously
 110  * the leaf being queried must have an entry in the lookup table.
 111  */
 112 static __always_inline void reverse_cpuid_check(unsigned int x86_leaf)
 113 {
 114         BUILD_BUG_ON(NR_CPUID_WORDS != NCAPINTS);
 115         BUILD_BUG_ON(x86_leaf == CPUID_LNX_1);
 116         BUILD_BUG_ON(x86_leaf == CPUID_LNX_2);
 117         BUILD_BUG_ON(x86_leaf == CPUID_LNX_3);
 118         BUILD_BUG_ON(x86_leaf == CPUID_LNX_4);
 119         BUILD_BUG_ON(x86_leaf == CPUID_LNX_5);
 120         BUILD_BUG_ON(x86_leaf >= ARRAY_SIZE(reverse_cpuid));
 121         BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0);
 122 }
 123
 124 /*
 125  * Translate feature bits that are scattered in the kernel's cpufeatures word
 126  * into KVM feature words that align with hardware's definitions.
 127  */
 128 static __always_inline u32 __feature_translate(int x86_feature)
 129 {
 130 #define KVM_X86_TRANSLATE_FEATURE(f)    \
 131         case X86_FEATURE_##f: return KVM_X86_FEATURE_##f
 132
 133         switch (x86_feature) {
 134         KVM_X86_TRANSLATE_FEATURE(SGX1);
 135         KVM_X86_TRANSLATE_FEATURE(SGX2);
 136         KVM_X86_TRANSLATE_FEATURE(SGX_EDECCSSA);
 137         KVM_X86_TRANSLATE_FEATURE(CONSTANT_TSC);
 138         KVM_X86_TRANSLATE_FEATURE(PERFMON_V2);
 139         KVM_X86_TRANSLATE_FEATURE(RRSBA_CTRL);
 140         KVM_X86_TRANSLATE_FEATURE(BHI_CTRL);
 141         default:
 142                 return x86_feature;
 143         }
 144 }
 145
 146 static __always_inline u32 __feature_leaf(int x86_feature)
 147 {
 148         return __feature_translate(x86_feature) / 32;
 149 }
 150
 151 /*
 152  * Retrieve the bit mask from an X86_FEATURE_* definition.  Features contain
 153  * the hardware defined bit number (stored in bits 4:0) and a software defined
 154  * "word" (stored in bits 31:5).  The word is used to index into arrays of
 155  * bit masks that hold the per-cpu feature capabilities, e.g. this_cpu_has().
 156  */
 157 static __always_inline u32 __feature_bit(int x86_feature)
 158 {
 159         x86_feature = __feature_translate(x86_feature);
 160
 161         reverse_cpuid_check(x86_feature / 32);
 162         return 1 << (x86_feature & 31);
 163 }
 164
 165 #define feature_bit(name)  __feature_bit(X86_FEATURE_##name)
 166
 167 static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned int x86_feature)
 168 {
 169         unsigned int x86_leaf = __feature_leaf(x86_feature);
 170
 171         reverse_cpuid_check(x86_leaf);
 172         return reverse_cpuid[x86_leaf];
 173 }
 174
 175 static __always_inline u32 *__cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry,
 176                                                   u32 reg)
 177 {
 178         switch (reg) {
 179         case CPUID_EAX:
 180                 return &entry->eax;
 181         case CPUID_EBX:
 182                 return &entry->ebx;
 183         case CPUID_ECX:
 184                 return &entry->ecx;
 185         case CPUID_EDX:
 186                 return &entry->edx;
 187         default:
 188                 BUILD_BUG();
 189                 return NULL;
 190         }
 191 }
 192
 193 static __always_inline u32 *cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry,
 194                                                 unsigned int x86_feature)
 195 {
 196         const struct cpuid_reg cpuid = x86_feature_cpuid(x86_feature);
 197
 198         return __cpuid_entry_get_reg(entry, cpuid.reg);
 199 }
 200
 201 static __always_inline u32 cpuid_entry_get(struct kvm_cpuid_entry2 *entry,
 202                                            unsigned int x86_feature)
 203 {
 204         u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
 205
 206         return *reg & __feature_bit(x86_feature);
 207 }
 208
 209 static __always_inline bool cpuid_entry_has(struct kvm_cpuid_entry2 *entry,
 210                                             unsigned int x86_feature)
 211 {
 212         return cpuid_entry_get(entry, x86_feature);
 213 }
 214
 215 static __always_inline void cpuid_entry_clear(struct kvm_cpuid_entry2 *entry,
 216                                               unsigned int x86_feature)
 217 {
 218         u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
 219
 220         *reg &= ~__feature_bit(x86_feature);
 221 }
 222
 223 static __always_inline void cpuid_entry_set(struct kvm_cpuid_entry2 *entry,
 224                                             unsigned int x86_feature)
 225 {
 226         u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
 227
 228         *reg |= __feature_bit(x86_feature);
 229 }
 230
 231 static __always_inline void cpuid_entry_change(struct kvm_cpuid_entry2 *entry,
 232                                                unsigned int x86_feature,
 233                                                bool set)
 234 {
 235         u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
 236
 237         /*
 238          * Open coded instead of using cpuid_entry_{clear,set}() to coerce the
 239          * compiler into using CMOV instead of Jcc when possible.
 240          */
 241         if (set)
 242                 *reg |= __feature_bit(x86_feature);
 243         else
 244                 *reg &= ~__feature_bit(x86_feature);
 245 }
 246
 247 #endif /* ARCH_X86_KVM_REVERSE_CPUID_H */