cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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virtext.h (3084B)

      1/* SPDX-License-Identifier: GPL-2.0-only */
      2/* CPU virtualization extensions handling
      3 *
      4 * This should carry the code for handling CPU virtualization extensions
      5 * that needs to live in the kernel core.
      6 *
      7 * Author: Eduardo Habkost <ehabkost@redhat.com>
      8 *
      9 * Copyright (C) 2008, Red Hat Inc.
     10 *
     11 * Contains code from KVM, Copyright (C) 2006 Qumranet, Inc.
     12 */
     13#ifndef _ASM_X86_VIRTEX_H
     14#define _ASM_X86_VIRTEX_H
     15
     16#include <asm/processor.h>
     17
     18#include <asm/vmx.h>
     19#include <asm/svm.h>
     20#include <asm/tlbflush.h>
     21
     22/*
     23 * VMX functions:
     24 */
     25
     26static inline int cpu_has_vmx(void)
     27{
     28	unsigned long ecx = cpuid_ecx(1);
     29	return test_bit(5, &ecx); /* CPUID.1:ECX.VMX[bit 5] -> VT */
     30}
     31
     32
     33/**
     34 * cpu_vmxoff() - Disable VMX on the current CPU
     35 *
     36 * Disable VMX and clear CR4.VMXE (even if VMXOFF faults)
     37 *
     38 * Note, VMXOFF causes a #UD if the CPU is !post-VMXON, but it's impossible to
     39 * atomically track post-VMXON state, e.g. this may be called in NMI context.
     40 * Eat all faults as all other faults on VMXOFF faults are mode related, i.e.
     41 * faults are guaranteed to be due to the !post-VMXON check unless the CPU is
     42 * magically in RM, VM86, compat mode, or at CPL>0.
     43 */
     44static inline int cpu_vmxoff(void)
     45{
     46	asm_volatile_goto("1: vmxoff\n\t"
     47			  _ASM_EXTABLE(1b, %l[fault])
     48			  ::: "cc", "memory" : fault);
     49
     50	cr4_clear_bits(X86_CR4_VMXE);
     51	return 0;
     52
     53fault:
     54	cr4_clear_bits(X86_CR4_VMXE);
     55	return -EIO;
     56}
     57
     58static inline int cpu_vmx_enabled(void)
     59{
     60	return __read_cr4() & X86_CR4_VMXE;
     61}
     62
     63/** Disable VMX if it is enabled on the current CPU
     64 *
     65 * You shouldn't call this if cpu_has_vmx() returns 0.
     66 */
     67static inline void __cpu_emergency_vmxoff(void)
     68{
     69	if (cpu_vmx_enabled())
     70		cpu_vmxoff();
     71}
     72
     73/** Disable VMX if it is supported and enabled on the current CPU
     74 */
     75static inline void cpu_emergency_vmxoff(void)
     76{
     77	if (cpu_has_vmx())
     78		__cpu_emergency_vmxoff();
     79}
     80
     81
     82
     83
     84/*
     85 * SVM functions:
     86 */
     87
     88/** Check if the CPU has SVM support
     89 *
     90 * You can use the 'msg' arg to get a message describing the problem,
     91 * if the function returns zero. Simply pass NULL if you are not interested
     92 * on the messages; gcc should take care of not generating code for
     93 * the messages on this case.
     94 */
     95static inline int cpu_has_svm(const char **msg)
     96{
     97	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
     98	    boot_cpu_data.x86_vendor != X86_VENDOR_HYGON) {
     99		if (msg)
    100			*msg = "not amd or hygon";
    101		return 0;
    102	}
    103
    104	if (boot_cpu_data.extended_cpuid_level < SVM_CPUID_FUNC) {
    105		if (msg)
    106			*msg = "can't execute cpuid_8000000a";
    107		return 0;
    108	}
    109
    110	if (!boot_cpu_has(X86_FEATURE_SVM)) {
    111		if (msg)
    112			*msg = "svm not available";
    113		return 0;
    114	}
    115	return 1;
    116}
    117
    118
    119/** Disable SVM on the current CPU
    120 *
    121 * You should call this only if cpu_has_svm() returned true.
    122 */
    123static inline void cpu_svm_disable(void)
    124{
    125	uint64_t efer;
    126
    127	wrmsrl(MSR_VM_HSAVE_PA, 0);
    128	rdmsrl(MSR_EFER, efer);
    129	wrmsrl(MSR_EFER, efer & ~EFER_SVME);
    130}
    131
    132/** Makes sure SVM is disabled, if it is supported on the CPU
    133 */
    134static inline void cpu_emergency_svm_disable(void)
    135{
    136	if (cpu_has_svm(NULL))
    137		cpu_svm_disable();
    138}
    139
    140#endif /* _ASM_X86_VIRTEX_H */