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 NR_KVM_CPU_CAPS,
20
21 NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS,
22 };
23
24 /*
25 * Define a KVM-only feature flag.
26 *
27 * For features that are scattered by cpufeatures.h, __feature_translate() also
28 * needs to be updated to translate the kernel-defined feature into the
29 * KVM-defined feature.
30 *
31 * For features that are 100% KVM-only, i.e. not defined by cpufeatures.h,
32 * forego the intermediate KVM_X86_FEATURE and directly define X86_FEATURE_* so
33 * that X86_FEATURE_* can be used in KVM. No __feature_translate() handling is
34 * needed in this case.
35 */
36 #define KVM_X86_FEATURE(w, f) ((w)*32 + (f))
37
38 /* Intel-defined SGX sub-features, CPUID level 0x12 (EAX). */
39 #define KVM_X86_FEATURE_SGX1 KVM_X86_FEATURE(CPUID_12_EAX, 0)
40 #define KVM_X86_FEATURE_SGX2 KVM_X86_FEATURE(CPUID_12_EAX, 1)
41 #define KVM_X86_FEATURE_SGX_EDECCSSA KVM_X86_FEATURE(CPUID_12_EAX, 11)
42
43 /* Intel-defined sub-features, CPUID level 0x00000007:1 (EDX) */
44 #define X86_FEATURE_AVX_VNNI_INT8 KVM_X86_FEATURE(CPUID_7_1_EDX, 4)
45 #define X86_FEATURE_AVX_NE_CONVERT KVM_X86_FEATURE(CPUID_7_1_EDX, 5)
46 #define X86_FEATURE_AMX_COMPLEX KVM_X86_FEATURE(CPUID_7_1_EDX, 8)
47 #define X86_FEATURE_PREFETCHITI KVM_X86_FEATURE(CPUID_7_1_EDX, 14)
48
49 /* CPUID level 0x80000007 (EDX). */
50 #define KVM_X86_FEATURE_CONSTANT_TSC KVM_X86_FEATURE(CPUID_8000_0007_EDX, 8)
51
52 /* CPUID level 0x80000022 (EAX) */
53 #define KVM_X86_FEATURE_PERFMON_V2 KVM_X86_FEATURE(CPUID_8000_0022_EAX, 0)
54
55 struct cpuid_reg {
56 u32 function;
57 u32 index;
58 int reg;
59 };
60
61 static const struct cpuid_reg reverse_cpuid[] = {
62 [CPUID_1_EDX] = { 1, 0, CPUID_EDX},
63 [CPUID_8000_0001_EDX] = {0x80000001, 0, CPUID_EDX},
64 [CPUID_8086_0001_EDX] = {0x80860001, 0, CPUID_EDX},
65 [CPUID_1_ECX] = { 1, 0, CPUID_ECX},
66 [CPUID_C000_0001_EDX] = {0xc0000001, 0, CPUID_EDX},
67 [CPUID_8000_0001_ECX] = {0x80000001, 0, CPUID_ECX},
68 [CPUID_7_0_EBX] = { 7, 0, CPUID_EBX},
69 [CPUID_D_1_EAX] = { 0xd, 1, CPUID_EAX},
70 [CPUID_8000_0008_EBX] = {0x80000008, 0, CPUID_EBX},
71 [CPUID_6_EAX] = { 6, 0, CPUID_EAX},
72 [CPUID_8000_000A_EDX] = {0x8000000a, 0, CPUID_EDX},
73 [CPUID_7_ECX] = { 7, 0, CPUID_ECX},
74 [CPUID_8000_0007_EBX] = {0x80000007, 0, CPUID_EBX},
75 [CPUID_7_EDX] = { 7, 0, CPUID_EDX},
76 [CPUID_7_1_EAX] = { 7, 1, CPUID_EAX},
77 [CPUID_12_EAX] = {0x00000012, 0, CPUID_EAX},
78 [CPUID_8000_001F_EAX] = {0x8000001f, 0, CPUID_EAX},
79 [CPUID_7_1_EDX] = { 7, 1, CPUID_EDX},
80 [CPUID_8000_0007_EDX] = {0x80000007, 0, CPUID_EDX},
81 [CPUID_8000_0021_EAX] = {0x80000021, 0, CPUID_EAX},
82 [CPUID_8000_0022_EAX] = {0x80000022, 0, CPUID_EAX},
83 };
84
85 /*
86 * Reverse CPUID and its derivatives can only be used for hardware-defined
87 * feature words, i.e. words whose bits directly correspond to a CPUID leaf.
88 * Retrieving a feature bit or masking guest CPUID from a Linux-defined word
89 * is nonsensical as the bit number/mask is an arbitrary software-defined value
90 * and can't be used by KVM to query/control guest capabilities. And obviously
91 * the leaf being queried must have an entry in the lookup table.
92 */
reverse_cpuid_check(unsigned int x86_leaf)93 static __always_inline void reverse_cpuid_check(unsigned int x86_leaf)
94 {
95 BUILD_BUG_ON(x86_leaf == CPUID_LNX_1);
96 BUILD_BUG_ON(x86_leaf == CPUID_LNX_2);
97 BUILD_BUG_ON(x86_leaf == CPUID_LNX_3);
98 BUILD_BUG_ON(x86_leaf == CPUID_LNX_4);
99 BUILD_BUG_ON(x86_leaf >= ARRAY_SIZE(reverse_cpuid));
100 BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0);
101 }
102
103 /*
104 * Translate feature bits that are scattered in the kernel's cpufeatures word
105 * into KVM feature words that align with hardware's definitions.
106 */
__feature_translate(int x86_feature)107 static __always_inline u32 __feature_translate(int x86_feature)
108 {
109 if (x86_feature == X86_FEATURE_SGX1)
110 return KVM_X86_FEATURE_SGX1;
111 else if (x86_feature == X86_FEATURE_SGX2)
112 return KVM_X86_FEATURE_SGX2;
113 else if (x86_feature == X86_FEATURE_SGX_EDECCSSA)
114 return KVM_X86_FEATURE_SGX_EDECCSSA;
115 else if (x86_feature == X86_FEATURE_CONSTANT_TSC)
116 return KVM_X86_FEATURE_CONSTANT_TSC;
117 else if (x86_feature == X86_FEATURE_PERFMON_V2)
118 return KVM_X86_FEATURE_PERFMON_V2;
119
120 return x86_feature;
121 }
122
__feature_leaf(int x86_feature)123 static __always_inline u32 __feature_leaf(int x86_feature)
124 {
125 return __feature_translate(x86_feature) / 32;
126 }
127
128 /*
129 * Retrieve the bit mask from an X86_FEATURE_* definition. Features contain
130 * the hardware defined bit number (stored in bits 4:0) and a software defined
131 * "word" (stored in bits 31:5). The word is used to index into arrays of
132 * bit masks that hold the per-cpu feature capabilities, e.g. this_cpu_has().
133 */
__feature_bit(int x86_feature)134 static __always_inline u32 __feature_bit(int x86_feature)
135 {
136 x86_feature = __feature_translate(x86_feature);
137
138 reverse_cpuid_check(x86_feature / 32);
139 return 1 << (x86_feature & 31);
140 }
141
142 #define feature_bit(name) __feature_bit(X86_FEATURE_##name)
143
x86_feature_cpuid(unsigned int x86_feature)144 static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned int x86_feature)
145 {
146 unsigned int x86_leaf = __feature_leaf(x86_feature);
147
148 reverse_cpuid_check(x86_leaf);
149 return reverse_cpuid[x86_leaf];
150 }
151
__cpuid_entry_get_reg(struct kvm_cpuid_entry2 * entry,u32 reg)152 static __always_inline u32 *__cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry,
153 u32 reg)
154 {
155 switch (reg) {
156 case CPUID_EAX:
157 return &entry->eax;
158 case CPUID_EBX:
159 return &entry->ebx;
160 case CPUID_ECX:
161 return &entry->ecx;
162 case CPUID_EDX:
163 return &entry->edx;
164 default:
165 BUILD_BUG();
166 return NULL;
167 }
168 }
169
cpuid_entry_get_reg(struct kvm_cpuid_entry2 * entry,unsigned int x86_feature)170 static __always_inline u32 *cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry,
171 unsigned int x86_feature)
172 {
173 const struct cpuid_reg cpuid = x86_feature_cpuid(x86_feature);
174
175 return __cpuid_entry_get_reg(entry, cpuid.reg);
176 }
177
cpuid_entry_get(struct kvm_cpuid_entry2 * entry,unsigned int x86_feature)178 static __always_inline u32 cpuid_entry_get(struct kvm_cpuid_entry2 *entry,
179 unsigned int x86_feature)
180 {
181 u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
182
183 return *reg & __feature_bit(x86_feature);
184 }
185
cpuid_entry_has(struct kvm_cpuid_entry2 * entry,unsigned int x86_feature)186 static __always_inline bool cpuid_entry_has(struct kvm_cpuid_entry2 *entry,
187 unsigned int x86_feature)
188 {
189 return cpuid_entry_get(entry, x86_feature);
190 }
191
cpuid_entry_clear(struct kvm_cpuid_entry2 * entry,unsigned int x86_feature)192 static __always_inline void cpuid_entry_clear(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
cpuid_entry_set(struct kvm_cpuid_entry2 * entry,unsigned int x86_feature)200 static __always_inline void cpuid_entry_set(struct kvm_cpuid_entry2 *entry,
201 unsigned int x86_feature)
202 {
203 u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
204
205 *reg |= __feature_bit(x86_feature);
206 }
207
cpuid_entry_change(struct kvm_cpuid_entry2 * entry,unsigned int x86_feature,bool set)208 static __always_inline void cpuid_entry_change(struct kvm_cpuid_entry2 *entry,
209 unsigned int x86_feature,
210 bool set)
211 {
212 u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
213
214 /*
215 * Open coded instead of using cpuid_entry_{clear,set}() to coerce the
216 * compiler into using CMOV instead of Jcc when possible.
217 */
218 if (set)
219 *reg |= __feature_bit(x86_feature);
220 else
221 *reg &= ~__feature_bit(x86_feature);
222 }
223
224 #endif /* ARCH_X86_KVM_REVERSE_CPUID_H */
225