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 */
14enum 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
55struct cpuid_reg {
56 u32 function;
57 u32 index;
58 int reg;
59};
60
61static const struct cpuid_reg reverse_cpuid[] = {
62 [CPUID_1_EDX] = { 1, 0, CPUID_EDX},
63 [CPUID_8000_0001_EDX] = {.function: 0x80000001, .index: 0, .reg: CPUID_EDX},
64 [CPUID_8086_0001_EDX] = {.function: 0x80860001, .index: 0, .reg: CPUID_EDX},
65 [CPUID_1_ECX] = { .function: 1, .index: 0, .reg: CPUID_ECX},
66 [CPUID_C000_0001_EDX] = {.function: 0xc0000001, .index: 0, .reg: CPUID_EDX},
67 [CPUID_8000_0001_ECX] = {.function: 0x80000001, .index: 0, .reg: CPUID_ECX},
68 [CPUID_7_0_EBX] = { .function: 7, .index: 0, .reg: CPUID_EBX},
69 [CPUID_D_1_EAX] = { .function: 0xd, .index: 1, .reg: CPUID_EAX},
70 [CPUID_8000_0008_EBX] = {.function: 0x80000008, .index: 0, .reg: CPUID_EBX},
71 [CPUID_6_EAX] = { .function: 6, .index: 0, .reg: CPUID_EAX},
72 [CPUID_8000_000A_EDX] = {.function: 0x8000000a, .index: 0, .reg: CPUID_EDX},
73 [CPUID_7_ECX] = { .function: 7, .index: 0, .reg: CPUID_ECX},
74 [CPUID_8000_0007_EBX] = {.function: 0x80000007, .index: 0, .reg: CPUID_EBX},
75 [CPUID_7_EDX] = { .function: 7, .index: 0, .reg: CPUID_EDX},
76 [CPUID_7_1_EAX] = { .function: 7, .index: 1, .reg: CPUID_EAX},
77 [CPUID_12_EAX] = {.function: 0x00000012, .index: 0, .reg: CPUID_EAX},
78 [CPUID_8000_001F_EAX] = {.function: 0x8000001f, .index: 0, .reg: CPUID_EAX},
79 [CPUID_7_1_EDX] = { .function: 7, .index: 1, .reg: CPUID_EDX},
80 [CPUID_8000_0007_EDX] = {.function: 0x80000007, .index: 0, .reg: CPUID_EDX},
81 [CPUID_8000_0021_EAX] = {.function: 0x80000021, .index: 0, .reg: CPUID_EAX},
82 [CPUID_8000_0022_EAX] = {.function: 0x80000022, .index: 0, .reg: 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 */
93static __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 */
107static __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
123static __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 */
134static __always_inline u32 __feature_bit(int x86_feature)
135{
136 x86_feature = __feature_translate(x86_feature);
137
138 reverse_cpuid_check(x86_leaf: x86_feature / 32);
139 return 1 << (x86_feature & 31);
140}
141
142#define feature_bit(name) __feature_bit(X86_FEATURE_##name)
143
144static __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
152static __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
170static __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, reg: cpuid.reg);
176}
177
178static __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
186static __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
192static __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
200static __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
208static __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

source code of linux/arch/x86/kvm/reverse_cpuid.h