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