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Wed, 02 Nov 2022 16:19:30 -0700 (PDT) Date: Wed, 2 Nov 2022 23:18:37 +0000 In-Reply-To: <20221102231911.3107438-1-seanjc@google.com> Mime-Version: 1.0 References: <20221102231911.3107438-1-seanjc@google.com> X-Mailer: git-send-email 2.38.1.431.g37b22c650d-goog Message-ID: <20221102231911.3107438-11-seanjc@google.com> Subject: [PATCH 10/44] KVM: VMX: Clean up eVMCS enabling if KVM initialization fails From: Sean Christopherson To: Paolo Bonzini , Marc Zyngier , Huacai Chen , Aleksandar Markovic , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Matthew Rosato , Eric Farman , Sean Christopherson , Vitaly Kuznetsov Content-Type: text/plain; charset="UTF-8" X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Sean Christopherson Cc: kvm@vger.kernel.org, David Hildenbrand , Atish Patra , linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-s390@vger.kernel.org, Chao Gao , Suzuki K Poulose , Yuan Yao , kvmarm@lists.linux.dev, Thomas Gleixner , Alexandru Elisei , linux-arm-kernel@lists.infradead.org, Isaku Yamahata , Fabiano Rosas , linux-mips@vger.kernel.org, Oliver Upton , James Morse , kvm-riscv@lists.infradead.org, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" To make it obvious that KVM doesn't have a lurking bug, cleanup eVMCS enabling if kvm_init() fails even though the enabling doesn't strictly need to be unwound. eVMCS enabling only toggles values that are fully contained in the VMX module, i.e. it's technically ok to leave the values as-is since they'll disappear entirely when the module is unloaded, but doing proper cleanup is relatively simple, and having a chunk of code that isn't unwound is confusing. Signed-off-by: Sean Christopherson --- arch/x86/kvm/vmx/vmx.c | 137 +++++++++++++++++++++++------------------ 1 file changed, 78 insertions(+), 59 deletions(-) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 05a747c9a9ff..b3fd4049de01 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -524,6 +524,8 @@ static inline void vmx_segment_cache_clear(struct vcpu_vmx *vmx) static unsigned long host_idt_base; #if IS_ENABLED(CONFIG_HYPERV) +static struct kvm_x86_ops vmx_x86_ops __initdata; + static bool __read_mostly enlightened_vmcs = true; module_param(enlightened_vmcs, bool, 0444); @@ -552,6 +554,71 @@ static int hv_enable_direct_tlbflush(struct kvm_vcpu *vcpu) return 0; } +static __init void hv_setup_evmcs(void) +{ + int cpu; + + if (!enlightened_vmcs) + return; + + /* + * Enlightened VMCS usage should be recommended and the host needs + * to support eVMCS v1 or above. + */ + if (ms_hyperv.hints & HV_X64_ENLIGHTENED_VMCS_RECOMMENDED && + (ms_hyperv.nested_features & HV_X64_ENLIGHTENED_VMCS_VERSION) >= + KVM_EVMCS_VERSION) { + + /* Check that we have assist pages on all online CPUs */ + for_each_online_cpu(cpu) { + if (!hv_get_vp_assist_page(cpu)) { + enlightened_vmcs = false; + break; + } + } + + if (enlightened_vmcs) { + pr_info("KVM: vmx: using Hyper-V Enlightened VMCS\n"); + static_branch_enable(&enable_evmcs); + } + + if (ms_hyperv.nested_features & HV_X64_NESTED_DIRECT_FLUSH) + vmx_x86_ops.enable_direct_tlbflush + = hv_enable_direct_tlbflush; + + } else { + enlightened_vmcs = false; + } +} +static void hv_cleanup_evmcs(void) +{ + struct hv_vp_assist_page *vp_ap; + int cpu; + + if (!static_branch_unlikely(&enable_evmcs)) + return; + + /* + * Reset everything to support using non-enlightened VMCS access later + * (e.g. when we reload the module with enlightened_vmcs=0) + */ + for_each_online_cpu(cpu) { + vp_ap = hv_get_vp_assist_page(cpu); + + if (!vp_ap) + continue; + + vp_ap->nested_control.features.directhypercall = 0; + vp_ap->current_nested_vmcs = 0; + vp_ap->enlighten_vmentry = 0; + } + + static_branch_disable(&enable_evmcs); +} + +#else /* IS_ENABLED(CONFIG_HYPERV) */ +static void hv_setup_evmcs(void) {} +static void hv_cleanup_evmcs(void) {} #endif /* IS_ENABLED(CONFIG_HYPERV) */ /* @@ -8435,29 +8502,8 @@ static void vmx_exit(void) kvm_exit(); -#if IS_ENABLED(CONFIG_HYPERV) - if (static_branch_unlikely(&enable_evmcs)) { - int cpu; - struct hv_vp_assist_page *vp_ap; - /* - * Reset everything to support using non-enlightened VMCS - * access later (e.g. when we reload the module with - * enlightened_vmcs=0) - */ - for_each_online_cpu(cpu) { - vp_ap = hv_get_vp_assist_page(cpu); + hv_cleanup_evmcs(); - if (!vp_ap) - continue; - - vp_ap->nested_control.features.directhypercall = 0; - vp_ap->current_nested_vmcs = 0; - vp_ap->enlighten_vmentry = 0; - } - - static_branch_disable(&enable_evmcs); - } -#endif vmx_cleanup_l1d_flush(); allow_smaller_maxphyaddr = false; @@ -8468,43 +8514,12 @@ static int __init vmx_init(void) { int r, cpu; -#if IS_ENABLED(CONFIG_HYPERV) - /* - * Enlightened VMCS usage should be recommended and the host needs - * to support eVMCS v1 or above. We can also disable eVMCS support - * with module parameter. - */ - if (enlightened_vmcs && - ms_hyperv.hints & HV_X64_ENLIGHTENED_VMCS_RECOMMENDED && - (ms_hyperv.nested_features & HV_X64_ENLIGHTENED_VMCS_VERSION) >= - KVM_EVMCS_VERSION) { - - /* Check that we have assist pages on all online CPUs */ - for_each_online_cpu(cpu) { - if (!hv_get_vp_assist_page(cpu)) { - enlightened_vmcs = false; - break; - } - } - - if (enlightened_vmcs) { - pr_info("KVM: vmx: using Hyper-V Enlightened VMCS\n"); - static_branch_enable(&enable_evmcs); - } - - if (ms_hyperv.nested_features & HV_X64_NESTED_DIRECT_FLUSH) - vmx_x86_ops.enable_direct_tlbflush - = hv_enable_direct_tlbflush; - - } else { - enlightened_vmcs = false; - } -#endif + hv_setup_evmcs(); r = kvm_init(&vmx_init_ops, sizeof(struct vcpu_vmx), __alignof__(struct vcpu_vmx), THIS_MODULE); if (r) - return r; + goto err_kvm_init; /* * Must be called after kvm_init() so enable_ept is properly set @@ -8514,10 +8529,8 @@ static int __init vmx_init(void) * mitigation mode. */ r = vmx_setup_l1d_flush(vmentry_l1d_flush_param); - if (r) { - vmx_exit(); - return r; - } + if (r) + goto err_l1d_flush; vmx_setup_fb_clear_ctrl(); @@ -8542,5 +8555,11 @@ static int __init vmx_init(void) allow_smaller_maxphyaddr = true; return 0; + +err_l1d_flush: + vmx_exit(); +err_kvm_init: + hv_cleanup_evmcs(); + return r; } module_init(vmx_init); -- 2.38.1.431.g37b22c650d-goog