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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef ARCH_X86_KVM_REVERSE_CPUID_H
#define ARCH_X86_KVM_REVERSE_CPUID_H
#include <uapi/asm/kvm.h>
#include <asm/cpufeature.h>
#include <asm/cpufeatures.h>
/*
* Hardware-defined CPUID leafs that are scattered in the kernel, but need to
* be directly used by KVM. Note, these word values conflict with the kernel's
* "bug" caps, but KVM doesn't use those.
*/
enum kvm_only_cpuid_leafs {
CPUID_12_EAX = NCAPINTS,
NR_KVM_CPU_CAPS,
NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS,
};
#define KVM_X86_FEATURE(w, f) ((w)*32 + (f))
/* Intel-defined SGX sub-features, CPUID level 0x12 (EAX). */
#define KVM_X86_FEATURE_SGX1 KVM_X86_FEATURE(CPUID_12_EAX, 0)
#define KVM_X86_FEATURE_SGX2 KVM_X86_FEATURE(CPUID_12_EAX, 1)
struct cpuid_reg {
u32 function;
u32 index;
int reg;
};
static const struct cpuid_reg reverse_cpuid[] = {
[CPUID_1_EDX] = { 1, 0, CPUID_EDX},
[CPUID_8000_0001_EDX] = {0x80000001, 0, CPUID_EDX},
[CPUID_8086_0001_EDX] = {0x80860001, 0, CPUID_EDX},
[CPUID_1_ECX] = { 1, 0, CPUID_ECX},
[CPUID_C000_0001_EDX] = {0xc0000001, 0, CPUID_EDX},
[CPUID_8000_0001_ECX] = {0x80000001, 0, CPUID_ECX},
[CPUID_7_0_EBX] = { 7, 0, CPUID_EBX},
[CPUID_D_1_EAX] = { 0xd, 1, CPUID_EAX},
[CPUID_8000_0008_EBX] = {0x80000008, 0, CPUID_EBX},
[CPUID_6_EAX] = { 6, 0, CPUID_EAX},
[CPUID_8000_000A_EDX] = {0x8000000a, 0, CPUID_EDX},
[CPUID_7_ECX] = { 7, 0, CPUID_ECX},
[CPUID_8000_0007_EBX] = {0x80000007, 0, CPUID_EBX},
[CPUID_7_EDX] = { 7, 0, CPUID_EDX},
[CPUID_7_1_EAX] = { 7, 1, CPUID_EAX},
[CPUID_12_EAX] = {0x00000012, 0, CPUID_EAX},
[CPUID_8000_001F_EAX] = {0x8000001f, 0, CPUID_EAX},
[CPUID_8000_0021_EAX] = {0x80000021, 0, CPUID_EAX},
};
/*
* Reverse CPUID and its derivatives can only be used for hardware-defined
* feature words, i.e. words whose bits directly correspond to a CPUID leaf.
* Retrieving a feature bit or masking guest CPUID from a Linux-defined word
* is nonsensical as the bit number/mask is an arbitrary software-defined value
* and can't be used by KVM to query/control guest capabilities. And obviously
* the leaf being queried must have an entry in the lookup table.
*/
static __always_inline void reverse_cpuid_check(unsigned int x86_leaf)
{
BUILD_BUG_ON(x86_leaf == CPUID_LNX_1);
BUILD_BUG_ON(x86_leaf == CPUID_LNX_2);
BUILD_BUG_ON(x86_leaf == CPUID_LNX_3);
BUILD_BUG_ON(x86_leaf == CPUID_LNX_4);
BUILD_BUG_ON(x86_leaf >= ARRAY_SIZE(reverse_cpuid));
BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0);
}
/*
* Translate feature bits that are scattered in the kernel's cpufeatures word
* into KVM feature words that align with hardware's definitions.
*/
static __always_inline u32 __feature_translate(int x86_feature)
{
if (x86_feature == X86_FEATURE_SGX1)
return KVM_X86_FEATURE_SGX1;
else if (x86_feature == X86_FEATURE_SGX2)
return KVM_X86_FEATURE_SGX2;
return x86_feature;
}
static __always_inline u32 __feature_leaf(int x86_feature)
{
return __feature_translate(x86_feature) / 32;
}
/*
* Retrieve the bit mask from an X86_FEATURE_* definition. Features contain
* the hardware defined bit number (stored in bits 4:0) and a software defined
* "word" (stored in bits 31:5). The word is used to index into arrays of
* bit masks that hold the per-cpu feature capabilities, e.g. this_cpu_has().
*/
static __always_inline u32 __feature_bit(int x86_feature)
{
x86_feature = __feature_translate(x86_feature);
reverse_cpuid_check(x86_feature / 32);
return 1 << (x86_feature & 31);
}
#define feature_bit(name) __feature_bit(X86_FEATURE_##name)
static __always_inline struct cpuid_reg x86_feature_cpuid(unsigned int x86_feature)
{
unsigned int x86_leaf = __feature_leaf(x86_feature);
reverse_cpuid_check(x86_leaf);
return reverse_cpuid[x86_leaf];
}
static __always_inline u32 *__cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry,
u32 reg)
{
switch (reg) {
case CPUID_EAX:
return &entry->eax;
case CPUID_EBX:
return &entry->ebx;
case CPUID_ECX:
return &entry->ecx;
case CPUID_EDX:
return &entry->edx;
default:
BUILD_BUG();
return NULL;
}
}
static __always_inline u32 *cpuid_entry_get_reg(struct kvm_cpuid_entry2 *entry,
unsigned int x86_feature)
{
const struct cpuid_reg cpuid = x86_feature_cpuid(x86_feature);
return __cpuid_entry_get_reg(entry, cpuid.reg);
}
static __always_inline u32 cpuid_entry_get(struct kvm_cpuid_entry2 *entry,
unsigned int x86_feature)
{
u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
return *reg & __feature_bit(x86_feature);
}
static __always_inline bool cpuid_entry_has(struct kvm_cpuid_entry2 *entry,
unsigned int x86_feature)
{
return cpuid_entry_get(entry, x86_feature);
}
static __always_inline void cpuid_entry_clear(struct kvm_cpuid_entry2 *entry,
unsigned int x86_feature)
{
u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
*reg &= ~__feature_bit(x86_feature);
}
static __always_inline void cpuid_entry_set(struct kvm_cpuid_entry2 *entry,
unsigned int x86_feature)
{
u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
*reg |= __feature_bit(x86_feature);
}
static __always_inline void cpuid_entry_change(struct kvm_cpuid_entry2 *entry,
unsigned int x86_feature,
bool set)
{
u32 *reg = cpuid_entry_get_reg(entry, x86_feature);
/*
* Open coded instead of using cpuid_entry_{clear,set}() to coerce the
* compiler into using CMOV instead of Jcc when possible.
*/
if (set)
*reg |= __feature_bit(x86_feature);
else
*reg &= ~__feature_bit(x86_feature);
}
#endif /* ARCH_X86_KVM_REVERSE_CPUID_H */
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