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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 NR_KVM_CPU_CAPS,
18
19 NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS,
20};
21
22/*
23 * Define a KVM-only feature flag.
24 *
25 * For features that are scattered by cpufeatures.h, __feature_translate() also
26 * needs to be updated to translate the kernel-defined feature into the
27 * KVM-defined feature.
28 *
29 * For features that are 100% KVM-only, i.e. not defined by cpufeatures.h,
30 * forego the intermediate KVM_X86_FEATURE and directly define X86_FEATURE_* so
31 * that X86_FEATURE_* can be used in KVM. No __feature_translate() handling is
32 * needed in this case.
33 */
34#define KVM_X86_FEATURE(w, f) ((w)*32 + (f))
35
36/* Intel-defined SGX sub-features, CPUID level 0x12 (EAX). */
37#define KVM_X86_FEATURE_SGX1 KVM_X86_FEATURE(CPUID_12_EAX, 0)
38#define KVM_X86_FEATURE_SGX2 KVM_X86_FEATURE(CPUID_12_EAX, 1)
39#define KVM_X86_FEATURE_SGX_EDECCSSA KVM_X86_FEATURE(CPUID_12_EAX, 11)
40
41/* Intel-defined sub-features, CPUID level 0x00000007:1 (EDX) */
42#define X86_FEATURE_AVX_VNNI_INT8 KVM_X86_FEATURE(CPUID_7_1_EDX, 4)
43#define X86_FEATURE_AVX_NE_CONVERT KVM_X86_FEATURE(CPUID_7_1_EDX, 5)
44#define X86_FEATURE_PREFETCHITI KVM_X86_FEATURE(CPUID_7_1_EDX, 14)
45
46struct cpuid_reg {
47 u32 function;
48 u32 index;
49 int reg;
50};
51
52static const struct cpuid_reg reverse_cpuid[] = {
53 [CPUID_1_EDX] = { 1, 0, CPUID_EDX},
54 [CPUID_8000_0001_EDX] = {0x80000001, 0, CPUID_EDX},
55 [CPUID_8086_0001_EDX] = {0x80860001, 0, CPUID_EDX},
56 [CPUID_1_ECX] = { 1, 0, CPUID_ECX},
57 [CPUID_C000_0001_EDX] = {0xc0000001, 0, CPUID_EDX},
58 [CPUID_8000_0001_ECX] = {0x80000001, 0, CPUID_ECX},
59 [CPUID_7_0_EBX] = { 7, 0, CPUID_EBX},
60 [CPUID_D_1_EAX] = { 0xd, 1, CPUID_EAX},
61 [CPUID_8000_0008_EBX] = {0x80000008, 0, CPUID_EBX},
62 [CPUID_6_EAX] = { 6, 0, CPUID_EAX},
63 [CPUID_8000_000A_EDX] = {0x8000000a, 0, CPUID_EDX},
64 [CPUID_7_ECX] = { 7, 0, CPUID_ECX},
65 [CPUID_8000_0007_EBX] = {0x80000007, 0, CPUID_EBX},
66 [CPUID_7_EDX] = { 7, 0, CPUID_EDX},
67 [CPUID_7_1_EAX] = { 7, 1, CPUID_EAX},
68 [CPUID_12_EAX] = {0x00000012, 0, CPUID_EAX},
69 [CPUID_8000_001F_EAX] = {0x8000001f, 0, CPUID_EAX},
70 [CPUID_7_1_EDX] = { 7, 1, CPUID_EDX},
71};
72
73/*
74 * Reverse CPUID and its derivatives can only be used for hardware-defined
75 * feature words, i.e. words whose bits directly correspond to a CPUID leaf.
76 * Retrieving a feature bit or masking guest CPUID from a Linux-defined word
77 * is nonsensical as the bit number/mask is an arbitrary software-defined value
78 * and can't be used by KVM to query/control guest capabilities. And obviously
79 * the leaf being queried must have an entry in the lookup table.
80 */
81static __always_inline void reverse_cpuid_check(unsigned int x86_leaf)
82{
83 BUILD_BUG_ON(x86_leaf == CPUID_LNX_1);
84 BUILD_BUG_ON(x86_leaf == CPUID_LNX_2);
85 BUILD_BUG_ON(x86_leaf == CPUID_LNX_3);
86 BUILD_BUG_ON(x86_leaf == CPUID_LNX_4);
87 BUILD_BUG_ON(x86_leaf >= ARRAY_SIZE(reverse_cpuid));
88 BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0);
89}
90
91/*
92 * Translate feature bits that are scattered in the kernel's cpufeatures word
93 * into KVM feature words that align with hardware's definitions.
94 */
95static __always_inline u32 __feature_translate(int x86_feature)
96{
97 if (x86_feature == X86_FEATURE_SGX1)
98 return KVM_X86_FEATURE_SGX1;
99 else if (x86_feature == X86_FEATURE_SGX2)
100 return KVM_X86_FEATURE_SGX2;
101 else if (x86_feature == X86_FEATURE_SGX_EDECCSSA)
102 return KVM_X86_FEATURE_SGX_EDECCSSA;
103
104 return x86_feature;
105}
106
107static __always_inline u32 __feature_leaf(int x86_feature)
108{
109 return __feature_translate(x86_feature) / 32;
110}
111
112/*
113 * Retrieve the bit mask from an X86_FEATURE_* definition. Features contain
114 * the hardware defined bit number (stored in bits 4:0) and a software defined
115 * "word" (stored in bits 31:5). The word is used to index into arrays of
116 * bit masks that hold the per-cpu feature capabilities, e.g. this_cpu_has().
117 */
118static __always_inline u32 __feature_bit(int x86_feature)
119{
120 x86_feature = __feature_translate(x86_feature);
121
122 reverse_cpuid_check(x86_feature / 32);
123 return 1 << (x86_feature & 31);
124}
125
126#define feature_bit(name) __feature_bit(X86_FEATURE_##name)
127
128static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned int x86_feature)
129{
130 unsigned int x86_leaf = __feature_leaf(x86_feature);
131
132 reverse_cpuid_check(x86_leaf);
133 return reverse_cpuid[x86_leaf];
134}
135
136static __always_inline u32 *__cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry,
137 u32 reg)
138{
139 switch (reg) {
140 case CPUID_EAX:
141 return &entry->eax;
142 case CPUID_EBX:
143 return &entry->ebx;
144 case CPUID_ECX:
145 return &entry->ecx;
146 case CPUID_EDX:
147 return &entry->edx;
148 default:
149 BUILD_BUG();
150 return NULL;
151 }
152}
153
154static __always_inline u32 *cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry,
155 unsigned int x86_feature)
156{
157 const struct cpuid_reg cpuid = x86_feature_cpuid(x86_feature);
158
159 return __cpuid_entry_get_reg(entry, cpuid.reg);
160}
161
162static __always_inline u32 cpuid_entry_get(struct kvm_cpuid_entry2 *entry,
163 unsigned int x86_feature)
164{
165 u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
166
167 return *reg & __feature_bit(x86_feature);
168}
169
170static __always_inline bool cpuid_entry_has(struct kvm_cpuid_entry2 *entry,
171 unsigned int x86_feature)
172{
173 return cpuid_entry_get(entry, x86_feature);
174}
175
176static __always_inline void cpuid_entry_clear(struct kvm_cpuid_entry2 *entry,
177 unsigned int x86_feature)
178{
179 u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
180
181 *reg &= ~__feature_bit(x86_feature);
182}
183
184static __always_inline void cpuid_entry_set(struct kvm_cpuid_entry2 *entry,
185 unsigned int x86_feature)
186{
187 u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
188
189 *reg |= __feature_bit(x86_feature);
190}
191
192static __always_inline void cpuid_entry_change(struct kvm_cpuid_entry2 *entry,
193 unsigned int x86_feature,
194 bool set)
195{
196 u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
197
198 /*
199 * Open coded instead of using cpuid_entry_{clear,set}() to coerce the
200 * compiler into using CMOV instead of Jcc when possible.
201 */
202 if (set)
203 *reg |= __feature_bit(x86_feature);
204 else
205 *reg &= ~__feature_bit(x86_feature);
206}
207
208#endif /* ARCH_X86_KVM_REVERSE_CPUID_H */