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/* SPDX-License-Identifier: GPL-2.0-only */
/* CPU virtualization extensions handling
*
* This should carry the code for handling CPU virtualization extensions
* that needs to live in the kernel core.
*
* Author: Eduardo Habkost <ehabkost@redhat.com>
*
* Copyright (C) 2008, Red Hat Inc.
*
* Contains code from KVM, Copyright (C) 2006 Qumranet, Inc.
*/
#ifndef _ASM_X86_VIRTEX_H
#define _ASM_X86_VIRTEX_H
#include <asm/processor.h>
#include <asm/vmx.h>
#include <asm/svm.h>
#include <asm/tlbflush.h>
/*
* VMX functions:
*/
static inline int cpu_has_vmx(void)
{
unsigned long ecx = cpuid_ecx(1);
return test_bit(5, &ecx); /* CPUID.1:ECX.VMX[bit 5] -> VT */
}
/**
* cpu_vmxoff() - Disable VMX on the current CPU
*
* Disable VMX and clear CR4.VMXE (even if VMXOFF faults)
*
* Note, VMXOFF causes a #UD if the CPU is !post-VMXON, but it's impossible to
* atomically track post-VMXON state, e.g. this may be called in NMI context.
* Eat all faults as all other faults on VMXOFF faults are mode related, i.e.
* faults are guaranteed to be due to the !post-VMXON check unless the CPU is
* magically in RM, VM86, compat mode, or at CPL>0.
*/
static inline void cpu_vmxoff(void)
{
asm_volatile_goto("1: vmxoff\n\t"
_ASM_EXTABLE(1b, %l[fault]) :::: fault);
fault:
cr4_clear_bits(X86_CR4_VMXE);
}
static inline int cpu_vmx_enabled(void)
{
return __read_cr4() & X86_CR4_VMXE;
}
/** Disable VMX if it is enabled on the current CPU
*
* You shouldn't call this if cpu_has_vmx() returns 0.
*/
static inline void __cpu_emergency_vmxoff(void)
{
if (cpu_vmx_enabled())
cpu_vmxoff();
}
/** Disable VMX if it is supported and enabled on the current CPU
*/
static inline void cpu_emergency_vmxoff(void)
{
if (cpu_has_vmx())
__cpu_emergency_vmxoff();
}
/*
* SVM functions:
*/
/** Check if the CPU has SVM support
*
* You can use the 'msg' arg to get a message describing the problem,
* if the function returns zero. Simply pass NULL if you are not interested
* on the messages; gcc should take care of not generating code for
* the messages on this case.
*/
static inline int cpu_has_svm(const char **msg)
{
if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
boot_cpu_data.x86_vendor != X86_VENDOR_HYGON) {
if (msg)
*msg = "not amd or hygon";
return 0;
}
if (!boot_cpu_has(X86_FEATURE_SVM)) {
if (msg)
*msg = "svm not available";
return 0;
}
return 1;
}
/** Disable SVM on the current CPU
*
* You should call this only if cpu_has_svm() returned true.
*/
static inline void cpu_svm_disable(void)
{
uint64_t efer;
wrmsrl(MSR_VM_HSAVE_PA, 0);
rdmsrl(MSR_EFER, efer);
if (efer & EFER_SVME) {
/*
* Force GIF=1 prior to disabling SVM to ensure INIT and NMI
* aren't blocked, e.g. if a fatal error occurred between CLGI
* and STGI. Note, STGI may #UD if SVM is disabled from NMI
* context between reading EFER and executing STGI. In that
* case, GIF must already be set, otherwise the NMI would have
* been blocked, so just eat the fault.
*/
asm_volatile_goto("1: stgi\n\t"
_ASM_EXTABLE(1b, %l[fault])
::: "memory" : fault);
fault:
wrmsrl(MSR_EFER, efer & ~EFER_SVME);
}
}
/** Makes sure SVM is disabled, if it is supported on the CPU
*/
static inline void cpu_emergency_svm_disable(void)
{
if (cpu_has_svm(NULL))
cpu_svm_disable();
}
#endif /* _ASM_X86_VIRTEX_H */
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