From: Maxim Levitsky Date: Thu, 1 Oct 2020 11:29:54 +0000 (+0300) Subject: KVM: nSVM: implement on demand allocation of the nested state X-Git-Tag: v5.10.7~1315^2~33 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=2fcf4876ada8a293d3b92a1033b8b990a7c613d3;p=platform%2Fkernel%2Flinux-rpi.git 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 Message-Id: <20201001112954.6258-5-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index ba50ff6..9e4c226 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -481,6 +481,9 @@ int nested_svm_vmrun(struct vcpu_svm *svm) vmcb12 = map.hva; + if (WARN_ON_ONCE(!svm->nested.initialized)) + return -EINVAL; + if (!nested_vmcb_checks(svm, vmcb12)) { vmcb12->control.exit_code = SVM_EXIT_ERR; vmcb12->control.exit_code_hi = 0; @@ -698,6 +701,45 @@ int nested_svm_vmexit(struct vcpu_svm *svm) return 0; } +int svm_allocate_nested(struct vcpu_svm *svm) +{ + struct page *hsave_page; + + if (svm->nested.initialized) + return 0; + + hsave_page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO); + if (!hsave_page) + return -ENOMEM; + svm->nested.hsave = page_address(hsave_page); + + svm->nested.msrpm = svm_vcpu_alloc_msrpm(); + if (!svm->nested.msrpm) + goto err_free_hsave; + svm_vcpu_init_msrpm(&svm->vcpu, svm->nested.msrpm); + + svm->nested.initialized = true; + return 0; + +err_free_hsave: + __free_page(hsave_page); + return -ENOMEM; +} + +void svm_free_nested(struct vcpu_svm *svm) +{ + if (!svm->nested.initialized) + return; + + svm_vcpu_free_msrpm(svm->nested.msrpm); + svm->nested.msrpm = NULL; + + __free_page(virt_to_page(svm->nested.hsave)); + svm->nested.hsave = NULL; + + svm->nested.initialized = false; +} + /* * Forcibly leave nested mode in order to be able to reset the VCPU later on. */ diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 57e0f27..dc4fe57 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -266,6 +266,7 @@ static int get_max_npt_level(void) int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer) { struct vcpu_svm *svm = to_svm(vcpu); + u64 old_efer = vcpu->arch.efer; vcpu->arch.efer = efer; if (!npt_enabled) { @@ -276,9 +277,27 @@ int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer) efer &= ~EFER_LME; } - if (!(efer & EFER_SVME)) { - svm_leave_nested(svm); - svm_set_gif(svm, true); + if ((old_efer & EFER_SVME) != (efer & EFER_SVME)) { + if (!(efer & EFER_SVME)) { + svm_leave_nested(svm); + svm_set_gif(svm, true); + + /* + * Free the nested guest state, unless we are in SMM. + * In this case we will return to the nested guest + * as soon as we leave SMM. + */ + if (!is_smm(&svm->vcpu)) + svm_free_nested(svm); + + } else { + int ret = svm_allocate_nested(svm); + + if (ret) { + vcpu->arch.efer = old_efer; + return ret; + } + } } svm->vmcb->save.efer = efer | EFER_SVME; @@ -650,7 +669,7 @@ static void set_msr_interception(struct kvm_vcpu *vcpu, u32 *msrpm, u32 msr, set_msr_interception_bitmap(vcpu, msrpm, msr, read, write); } -static u32 *svm_vcpu_alloc_msrpm(void) +u32 *svm_vcpu_alloc_msrpm(void) { struct page *pages = alloc_pages(GFP_KERNEL_ACCOUNT, MSRPM_ALLOC_ORDER); u32 *msrpm; @@ -664,7 +683,7 @@ static u32 *svm_vcpu_alloc_msrpm(void) return msrpm; } -static void svm_vcpu_init_msrpm(struct kvm_vcpu *vcpu, u32 *msrpm) +void svm_vcpu_init_msrpm(struct kvm_vcpu *vcpu, u32 *msrpm) { int i; @@ -675,7 +694,8 @@ static void svm_vcpu_init_msrpm(struct kvm_vcpu *vcpu, u32 *msrpm) } } -static void svm_vcpu_free_msrpm(u32 *msrpm) + +void svm_vcpu_free_msrpm(u32 *msrpm) { __free_pages(virt_to_page(msrpm), MSRPM_ALLOC_ORDER); } @@ -1268,7 +1288,6 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu) { struct vcpu_svm *svm; struct page *vmcb_page; - struct page *hsave_page; int err; BUILD_BUG_ON(offsetof(struct vcpu_svm, vcpu) != 0); @@ -1279,13 +1298,9 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu) if (!vmcb_page) goto out; - hsave_page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO); - if (!hsave_page) - goto error_free_vmcb_page; - err = avic_init_vcpu(svm); if (err) - goto error_free_hsave_page; + goto error_free_vmcb_page; /* We initialize this flag to true to make sure that the is_running * bit would be set the first time the vcpu is loaded. @@ -1293,21 +1308,12 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu) if (irqchip_in_kernel(vcpu->kvm) && kvm_apicv_activated(vcpu->kvm)) svm->avic_is_running = true; - svm->nested.hsave = page_address(hsave_page); - svm->msrpm = svm_vcpu_alloc_msrpm(); if (!svm->msrpm) - goto error_free_hsave_page; + goto error_free_vmcb_page; svm_vcpu_init_msrpm(vcpu, svm->msrpm); - svm->nested.msrpm = svm_vcpu_alloc_msrpm(); - if (!svm->nested.msrpm) - goto error_free_msrpm; - - /* We only need the L1 pass-through MSR state, so leave vcpu as NULL */ - svm_vcpu_init_msrpm(vcpu, svm->nested.msrpm); - svm->vmcb = page_address(vmcb_page); svm->vmcb_pa = __sme_set(page_to_pfn(vmcb_page) << PAGE_SHIFT); svm->asid_generation = 0; @@ -1318,10 +1324,6 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu) return 0; -error_free_msrpm: - svm_vcpu_free_msrpm(svm->msrpm); -error_free_hsave_page: - __free_page(hsave_page); error_free_vmcb_page: __free_page(vmcb_page); out: @@ -1347,10 +1349,10 @@ static void svm_free_vcpu(struct kvm_vcpu *vcpu) */ svm_clear_current_vmcb(svm->vmcb); + svm_free_nested(svm); + __free_page(pfn_to_page(__sme_clr(svm->vmcb_pa) >> PAGE_SHIFT)); __free_pages(virt_to_page(svm->msrpm), MSRPM_ALLOC_ORDER); - __free_page(virt_to_page(svm->nested.hsave)); - __free_pages(virt_to_page(svm->nested.msrpm), MSRPM_ALLOC_ORDER); } static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu) @@ -4038,6 +4040,9 @@ static int svm_pre_leave_smm(struct kvm_vcpu *vcpu, const char *smstate) gpa_to_gfn(vmcb12_gpa), &map) == -EINVAL) return 1; + if (svm_allocate_nested(svm)) + return 1; + ret = enter_svm_guest_mode(svm, vmcb12_gpa, map.hva); kvm_vcpu_unmap(&svm->vcpu, &map, true); } diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index e7af21e..1d853fe 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -97,6 +97,8 @@ struct svm_nested_state { /* cache for control fields of the guest */ struct vmcb_control_area ctl; + + bool initialized; }; struct vcpu_svm { @@ -350,6 +352,10 @@ static inline bool gif_set(struct vcpu_svm *svm) #define MSR_INVALID 0xffffffffU u32 svm_msrpm_offset(u32 msr); +u32 *svm_vcpu_alloc_msrpm(void); +void svm_vcpu_init_msrpm(struct kvm_vcpu *vcpu, u32 *msrpm); +void svm_vcpu_free_msrpm(u32 *msrpm); + int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer); void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0); int svm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4); @@ -391,6 +397,8 @@ static inline bool nested_exit_on_nmi(struct vcpu_svm *svm) int enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa, struct vmcb *nested_vmcb); void svm_leave_nested(struct vcpu_svm *svm); +void svm_free_nested(struct vcpu_svm *svm); +int svm_allocate_nested(struct vcpu_svm *svm); int nested_svm_vmrun(struct vcpu_svm *svm); void nested_svm_vmloadsave(struct vmcb *from_vmcb, struct vmcb *to_vmcb); int nested_svm_vmexit(struct vcpu_svm *svm);