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KVM: nSVM: implement on demand allocation of the nested state
This way we don't waste memory on VMs which don't use nesting virtualization even when the host enabled it for them. Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20201001112954.6258-5-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Maxim Levitsky
Paolo Bonzini
parent
72f211ecaa
commit
2fcf4876ad
@ -481,6 +481,9 @@ int nested_svm_vmrun(struct vcpu_svm *svm)
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vmcb12 = map.hva;
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if (WARN_ON_ONCE(!svm->nested.initialized))
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return -EINVAL;
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if (!nested_vmcb_checks(svm, vmcb12)) {
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vmcb12->control.exit_code = SVM_EXIT_ERR;
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vmcb12->control.exit_code_hi = 0;
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@ -698,6 +701,45 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
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return 0;
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}
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int svm_allocate_nested(struct vcpu_svm *svm)
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{
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struct page *hsave_page;
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if (svm->nested.initialized)
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return 0;
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hsave_page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
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if (!hsave_page)
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return -ENOMEM;
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svm->nested.hsave = page_address(hsave_page);
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svm->nested.msrpm = svm_vcpu_alloc_msrpm();
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if (!svm->nested.msrpm)
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goto err_free_hsave;
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svm_vcpu_init_msrpm(&svm->vcpu, svm->nested.msrpm);
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svm->nested.initialized = true;
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return 0;
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err_free_hsave:
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__free_page(hsave_page);
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return -ENOMEM;
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}
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void svm_free_nested(struct vcpu_svm *svm)
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{
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if (!svm->nested.initialized)
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return;
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svm_vcpu_free_msrpm(svm->nested.msrpm);
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svm->nested.msrpm = NULL;
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__free_page(virt_to_page(svm->nested.hsave));
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svm->nested.hsave = NULL;
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svm->nested.initialized = false;
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}
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/*
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* Forcibly leave nested mode in order to be able to reset the VCPU later on.
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*/
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@ -266,6 +266,7 @@ static int get_max_npt_level(void)
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int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer)
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{
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struct vcpu_svm *svm = to_svm(vcpu);
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u64 old_efer = vcpu->arch.efer;
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vcpu->arch.efer = efer;
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if (!npt_enabled) {
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@ -276,9 +277,27 @@ int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer)
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efer &= ~EFER_LME;
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}
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if ((old_efer & EFER_SVME) != (efer & EFER_SVME)) {
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if (!(efer & EFER_SVME)) {
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svm_leave_nested(svm);
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svm_set_gif(svm, true);
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/*
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* Free the nested guest state, unless we are in SMM.
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* In this case we will return to the nested guest
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* as soon as we leave SMM.
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*/
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if (!is_smm(&svm->vcpu))
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svm_free_nested(svm);
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} else {
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int ret = svm_allocate_nested(svm);
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if (ret) {
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vcpu->arch.efer = old_efer;
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return ret;
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}
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}
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}
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svm->vmcb->save.efer = efer | EFER_SVME;
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@ -650,7 +669,7 @@ static void set_msr_interception(struct kvm_vcpu *vcpu, u32 *msrpm, u32 msr,
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set_msr_interception_bitmap(vcpu, msrpm, msr, read, write);
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}
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static u32 *svm_vcpu_alloc_msrpm(void)
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u32 *svm_vcpu_alloc_msrpm(void)
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{
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struct page *pages = alloc_pages(GFP_KERNEL_ACCOUNT, MSRPM_ALLOC_ORDER);
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u32 *msrpm;
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@ -664,7 +683,7 @@ static u32 *svm_vcpu_alloc_msrpm(void)
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return msrpm;
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}
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static void svm_vcpu_init_msrpm(struct kvm_vcpu *vcpu, u32 *msrpm)
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void svm_vcpu_init_msrpm(struct kvm_vcpu *vcpu, u32 *msrpm)
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{
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int i;
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@ -675,7 +694,8 @@ static void svm_vcpu_init_msrpm(struct kvm_vcpu *vcpu, u32 *msrpm)
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}
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}
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static void svm_vcpu_free_msrpm(u32 *msrpm)
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void svm_vcpu_free_msrpm(u32 *msrpm)
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{
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__free_pages(virt_to_page(msrpm), MSRPM_ALLOC_ORDER);
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}
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@ -1268,7 +1288,6 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
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{
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struct vcpu_svm *svm;
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struct page *vmcb_page;
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struct page *hsave_page;
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int err;
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BUILD_BUG_ON(offsetof(struct vcpu_svm, vcpu) != 0);
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@ -1279,13 +1298,9 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
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if (!vmcb_page)
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goto out;
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hsave_page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
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if (!hsave_page)
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goto error_free_vmcb_page;
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err = avic_init_vcpu(svm);
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if (err)
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goto error_free_hsave_page;
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goto error_free_vmcb_page;
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/* We initialize this flag to true to make sure that the is_running
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* bit would be set the first time the vcpu is loaded.
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@ -1293,21 +1308,12 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
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if (irqchip_in_kernel(vcpu->kvm) && kvm_apicv_activated(vcpu->kvm))
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svm->avic_is_running = true;
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svm->nested.hsave = page_address(hsave_page);
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svm->msrpm = svm_vcpu_alloc_msrpm();
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if (!svm->msrpm)
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goto error_free_hsave_page;
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goto error_free_vmcb_page;
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svm_vcpu_init_msrpm(vcpu, svm->msrpm);
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svm->nested.msrpm = svm_vcpu_alloc_msrpm();
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if (!svm->nested.msrpm)
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goto error_free_msrpm;
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/* We only need the L1 pass-through MSR state, so leave vcpu as NULL */
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svm_vcpu_init_msrpm(vcpu, svm->nested.msrpm);
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svm->vmcb = page_address(vmcb_page);
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svm->vmcb_pa = __sme_set(page_to_pfn(vmcb_page) << PAGE_SHIFT);
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svm->asid_generation = 0;
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@ -1318,10 +1324,6 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
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return 0;
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error_free_msrpm:
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svm_vcpu_free_msrpm(svm->msrpm);
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error_free_hsave_page:
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__free_page(hsave_page);
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error_free_vmcb_page:
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__free_page(vmcb_page);
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out:
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@ -1347,10 +1349,10 @@ static void svm_free_vcpu(struct kvm_vcpu *vcpu)
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*/
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svm_clear_current_vmcb(svm->vmcb);
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svm_free_nested(svm);
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__free_page(pfn_to_page(__sme_clr(svm->vmcb_pa) >> PAGE_SHIFT));
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__free_pages(virt_to_page(svm->msrpm), MSRPM_ALLOC_ORDER);
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__free_page(virt_to_page(svm->nested.hsave));
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__free_pages(virt_to_page(svm->nested.msrpm), MSRPM_ALLOC_ORDER);
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}
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static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
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@ -4038,6 +4040,9 @@ static int svm_pre_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
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gpa_to_gfn(vmcb12_gpa), &map) == -EINVAL)
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return 1;
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if (svm_allocate_nested(svm))
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return 1;
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ret = enter_svm_guest_mode(svm, vmcb12_gpa, map.hva);
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kvm_vcpu_unmap(&svm->vcpu, &map, true);
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}
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@ -97,6 +97,8 @@ struct svm_nested_state {
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/* cache for control fields of the guest */
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struct vmcb_control_area ctl;
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bool initialized;
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};
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struct vcpu_svm {
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@ -350,6 +352,10 @@ static inline bool gif_set(struct vcpu_svm *svm)
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#define MSR_INVALID 0xffffffffU
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u32 svm_msrpm_offset(u32 msr);
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u32 *svm_vcpu_alloc_msrpm(void);
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void svm_vcpu_init_msrpm(struct kvm_vcpu *vcpu, u32 *msrpm);
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void svm_vcpu_free_msrpm(u32 *msrpm);
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int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer);
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void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0);
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int svm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4);
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@ -391,6 +397,8 @@ static inline bool nested_exit_on_nmi(struct vcpu_svm *svm)
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int enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
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struct vmcb *nested_vmcb);
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void svm_leave_nested(struct vcpu_svm *svm);
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void svm_free_nested(struct vcpu_svm *svm);
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int svm_allocate_nested(struct vcpu_svm *svm);
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int nested_svm_vmrun(struct vcpu_svm *svm);
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void nested_svm_vmloadsave(struct vmcb *from_vmcb, struct vmcb *to_vmcb);
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int nested_svm_vmexit(struct vcpu_svm *svm);
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