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Linux kernel mirror (for testing)
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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 CPUID_7_2_EDX,
20 NR_KVM_CPU_CAPS,
21
22 NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS,
23};
24
25/*
26 * Define a KVM-only feature flag.
27 *
28 * For features that are scattered by cpufeatures.h, __feature_translate() also
29 * needs to be updated to translate the kernel-defined feature into the
30 * KVM-defined feature.
31 *
32 * For features that are 100% KVM-only, i.e. not defined by cpufeatures.h,
33 * forego the intermediate KVM_X86_FEATURE and directly define X86_FEATURE_* so
34 * that X86_FEATURE_* can be used in KVM. No __feature_translate() handling is
35 * needed in this case.
36 */
37#define KVM_X86_FEATURE(w, f) ((w)*32 + (f))
38
39/* Intel-defined SGX sub-features, CPUID level 0x12 (EAX). */
40#define KVM_X86_FEATURE_SGX1 KVM_X86_FEATURE(CPUID_12_EAX, 0)
41#define KVM_X86_FEATURE_SGX2 KVM_X86_FEATURE(CPUID_12_EAX, 1)
42#define KVM_X86_FEATURE_SGX_EDECCSSA KVM_X86_FEATURE(CPUID_12_EAX, 11)
43
44/* Intel-defined sub-features, CPUID level 0x00000007:1 (EDX) */
45#define X86_FEATURE_AVX_VNNI_INT8 KVM_X86_FEATURE(CPUID_7_1_EDX, 4)
46#define X86_FEATURE_AVX_NE_CONVERT KVM_X86_FEATURE(CPUID_7_1_EDX, 5)
47#define X86_FEATURE_AMX_COMPLEX KVM_X86_FEATURE(CPUID_7_1_EDX, 8)
48#define X86_FEATURE_PREFETCHITI KVM_X86_FEATURE(CPUID_7_1_EDX, 14)
49
50/* Intel-defined sub-features, CPUID level 0x00000007:2 (EDX) */
51#define X86_FEATURE_INTEL_PSFD KVM_X86_FEATURE(CPUID_7_2_EDX, 0)
52#define X86_FEATURE_IPRED_CTRL KVM_X86_FEATURE(CPUID_7_2_EDX, 1)
53#define KVM_X86_FEATURE_RRSBA_CTRL KVM_X86_FEATURE(CPUID_7_2_EDX, 2)
54#define X86_FEATURE_DDPD_U KVM_X86_FEATURE(CPUID_7_2_EDX, 3)
55#define X86_FEATURE_BHI_CTRL KVM_X86_FEATURE(CPUID_7_2_EDX, 4)
56#define X86_FEATURE_MCDT_NO KVM_X86_FEATURE(CPUID_7_2_EDX, 5)
57
58/* CPUID level 0x80000007 (EDX). */
59#define KVM_X86_FEATURE_CONSTANT_TSC KVM_X86_FEATURE(CPUID_8000_0007_EDX, 8)
60
61/* CPUID level 0x80000022 (EAX) */
62#define KVM_X86_FEATURE_PERFMON_V2 KVM_X86_FEATURE(CPUID_8000_0022_EAX, 0)
63
64struct cpuid_reg {
65 u32 function;
66 u32 index;
67 int reg;
68};
69
70static const struct cpuid_reg reverse_cpuid[] = {
71 [CPUID_1_EDX] = { 1, 0, CPUID_EDX},
72 [CPUID_8000_0001_EDX] = {0x80000001, 0, CPUID_EDX},
73 [CPUID_8086_0001_EDX] = {0x80860001, 0, CPUID_EDX},
74 [CPUID_1_ECX] = { 1, 0, CPUID_ECX},
75 [CPUID_C000_0001_EDX] = {0xc0000001, 0, CPUID_EDX},
76 [CPUID_8000_0001_ECX] = {0x80000001, 0, CPUID_ECX},
77 [CPUID_7_0_EBX] = { 7, 0, CPUID_EBX},
78 [CPUID_D_1_EAX] = { 0xd, 1, CPUID_EAX},
79 [CPUID_8000_0008_EBX] = {0x80000008, 0, CPUID_EBX},
80 [CPUID_6_EAX] = { 6, 0, CPUID_EAX},
81 [CPUID_8000_000A_EDX] = {0x8000000a, 0, CPUID_EDX},
82 [CPUID_7_ECX] = { 7, 0, CPUID_ECX},
83 [CPUID_8000_0007_EBX] = {0x80000007, 0, CPUID_EBX},
84 [CPUID_7_EDX] = { 7, 0, CPUID_EDX},
85 [CPUID_7_1_EAX] = { 7, 1, CPUID_EAX},
86 [CPUID_12_EAX] = {0x00000012, 0, CPUID_EAX},
87 [CPUID_8000_001F_EAX] = {0x8000001f, 0, CPUID_EAX},
88 [CPUID_7_1_EDX] = { 7, 1, CPUID_EDX},
89 [CPUID_8000_0007_EDX] = {0x80000007, 0, CPUID_EDX},
90 [CPUID_8000_0021_EAX] = {0x80000021, 0, CPUID_EAX},
91 [CPUID_8000_0022_EAX] = {0x80000022, 0, CPUID_EAX},
92 [CPUID_7_2_EDX] = { 7, 2, CPUID_EDX},
93};
94
95/*
96 * Reverse CPUID and its derivatives can only be used for hardware-defined
97 * feature words, i.e. words whose bits directly correspond to a CPUID leaf.
98 * Retrieving a feature bit or masking guest CPUID from a Linux-defined word
99 * is nonsensical as the bit number/mask is an arbitrary software-defined value
100 * and can't be used by KVM to query/control guest capabilities. And obviously
101 * the leaf being queried must have an entry in the lookup table.
102 */
103static __always_inline void reverse_cpuid_check(unsigned int x86_leaf)
104{
105 BUILD_BUG_ON(x86_leaf == CPUID_LNX_1);
106 BUILD_BUG_ON(x86_leaf == CPUID_LNX_2);
107 BUILD_BUG_ON(x86_leaf == CPUID_LNX_3);
108 BUILD_BUG_ON(x86_leaf == CPUID_LNX_4);
109 BUILD_BUG_ON(x86_leaf >= ARRAY_SIZE(reverse_cpuid));
110 BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0);
111}
112
113/*
114 * Translate feature bits that are scattered in the kernel's cpufeatures word
115 * into KVM feature words that align with hardware's definitions.
116 */
117static __always_inline u32 __feature_translate(int x86_feature)
118{
119#define KVM_X86_TRANSLATE_FEATURE(f) \
120 case X86_FEATURE_##f: return KVM_X86_FEATURE_##f
121
122 switch (x86_feature) {
123 KVM_X86_TRANSLATE_FEATURE(SGX1);
124 KVM_X86_TRANSLATE_FEATURE(SGX2);
125 KVM_X86_TRANSLATE_FEATURE(SGX_EDECCSSA);
126 KVM_X86_TRANSLATE_FEATURE(CONSTANT_TSC);
127 KVM_X86_TRANSLATE_FEATURE(PERFMON_V2);
128 KVM_X86_TRANSLATE_FEATURE(RRSBA_CTRL);
129 default:
130 return x86_feature;
131 }
132}
133
134static __always_inline u32 __feature_leaf(int x86_feature)
135{
136 return __feature_translate(x86_feature) / 32;
137}
138
139/*
140 * Retrieve the bit mask from an X86_FEATURE_* definition. Features contain
141 * the hardware defined bit number (stored in bits 4:0) and a software defined
142 * "word" (stored in bits 31:5). The word is used to index into arrays of
143 * bit masks that hold the per-cpu feature capabilities, e.g. this_cpu_has().
144 */
145static __always_inline u32 __feature_bit(int x86_feature)
146{
147 x86_feature = __feature_translate(x86_feature);
148
149 reverse_cpuid_check(x86_feature / 32);
150 return 1 << (x86_feature & 31);
151}
152
153#define feature_bit(name) __feature_bit(X86_FEATURE_##name)
154
155static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned int x86_feature)
156{
157 unsigned int x86_leaf = __feature_leaf(x86_feature);
158
159 reverse_cpuid_check(x86_leaf);
160 return reverse_cpuid[x86_leaf];
161}
162
163static __always_inline u32 *__cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry,
164 u32 reg)
165{
166 switch (reg) {
167 case CPUID_EAX:
168 return &entry->eax;
169 case CPUID_EBX:
170 return &entry->ebx;
171 case CPUID_ECX:
172 return &entry->ecx;
173 case CPUID_EDX:
174 return &entry->edx;
175 default:
176 BUILD_BUG();
177 return NULL;
178 }
179}
180
181static __always_inline u32 *cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry,
182 unsigned int x86_feature)
183{
184 const struct cpuid_reg cpuid = x86_feature_cpuid(x86_feature);
185
186 return __cpuid_entry_get_reg(entry, cpuid.reg);
187}
188
189static __always_inline u32 cpuid_entry_get(struct kvm_cpuid_entry2 *entry,
190 unsigned int x86_feature)
191{
192 u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
193
194 return *reg & __feature_bit(x86_feature);
195}
196
197static __always_inline bool cpuid_entry_has(struct kvm_cpuid_entry2 *entry,
198 unsigned int x86_feature)
199{
200 return cpuid_entry_get(entry, x86_feature);
201}
202
203static __always_inline void cpuid_entry_clear(struct kvm_cpuid_entry2 *entry,
204 unsigned int x86_feature)
205{
206 u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
207
208 *reg &= ~__feature_bit(x86_feature);
209}
210
211static __always_inline void cpuid_entry_set(struct kvm_cpuid_entry2 *entry,
212 unsigned int x86_feature)
213{
214 u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
215
216 *reg |= __feature_bit(x86_feature);
217}
218
219static __always_inline void cpuid_entry_change(struct kvm_cpuid_entry2 *entry,
220 unsigned int x86_feature,
221 bool set)
222{
223 u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
224
225 /*
226 * Open coded instead of using cpuid_entry_{clear,set}() to coerce the
227 * compiler into using CMOV instead of Jcc when possible.
228 */
229 if (set)
230 *reg |= __feature_bit(x86_feature);
231 else
232 *reg &= ~__feature_bit(x86_feature);
233}
234
235#endif /* ARCH_X86_KVM_REVERSE_CPUID_H */