diff options
| -rw-r--r-- | arch/x86/kvm/vmx/nested.c | 130 |
1 files changed, 12 insertions, 118 deletions
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index efca276c67f0..24a2d0fa1660 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -23,9 +23,6 @@ static bool __read_mostly enable_shadow_vmcs = 1; module_param_named(enable_shadow_vmcs, enable_shadow_vmcs, bool, S_IRUGO); -static bool __read_mostly nested_early_check = 0; -module_param(nested_early_check, bool, S_IRUGO); - #define CC KVM_NESTED_VMENTER_CONSISTENCY_CHECK /* @@ -2299,13 +2296,6 @@ static void prepare_vmcs02_constant_state(struct vcpu_vmx *vmx) return; vmx->nested.vmcs02_initialized = true; - /* - * If early consistency checks are enabled, stuff the EPT Pointer with - * a dummy *legal* value to avoid false positives on bad control state. - */ - if (enable_ept && nested_early_check) - vmcs_write64(EPT_POINTER, VMX_EPTP_MT_WB | VMX_EPTP_PWL_4); - if (vmx->ve_info) vmcs_write64(VE_INFORMATION_ADDRESS, __pa(vmx->ve_info)); @@ -2371,13 +2361,6 @@ static void prepare_vmcs02_early_rare(struct vcpu_vmx *vmx, else vmcs_write16(VIRTUAL_PROCESSOR_ID, vmx->vpid); } - - if (kvm_caps.has_tsc_control && nested_early_check) { - if (nested_cpu_has2(vmcs12, SECONDARY_EXEC_TSC_SCALING)) - vmcs_write64(TSC_MULTIPLIER, vmcs12->tsc_multiplier); - else - vmcs_write64(TSC_MULTIPLIER, 1); - } } static void prepare_vmcs02_early(struct vcpu_vmx *vmx, struct loaded_vmcs *vmcs01, @@ -3345,84 +3328,6 @@ static int nested_vmx_check_guest_state(struct kvm_vcpu *vcpu, return 0; } -static int nested_vmx_check_vmentry_hw(struct kvm_vcpu *vcpu) -{ - struct vcpu_vmx *vmx = to_vmx(vcpu); - unsigned long cr3, cr4; - bool vm_fail; - - if (!nested_early_check) - return 0; - - if (vmx->msr_autoload.host.nr) - vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, 0); - if (vmx->msr_autoload.guest.nr) - vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, 0); - - preempt_disable(); - - vmx_prepare_switch_to_guest(vcpu); - - /* - * Induce a consistency check VMExit by clearing bit 1 in GUEST_RFLAGS, - * which is reserved to '1' by hardware. GUEST_RFLAGS is guaranteed to - * be written (by prepare_vmcs02()) before the "real" VMEnter, i.e. - * there is no need to preserve other bits or save/restore the field. - */ - vmcs_writel(GUEST_RFLAGS, 0); - - cr3 = __get_current_cr3_fast(); - if (unlikely(cr3 != vmx->loaded_vmcs->host_state.cr3)) { - vmcs_writel(HOST_CR3, cr3); - vmx->loaded_vmcs->host_state.cr3 = cr3; - } - - cr4 = cr4_read_shadow(); - if (unlikely(cr4 != vmx->loaded_vmcs->host_state.cr4)) { - vmcs_writel(HOST_CR4, cr4); - vmx->loaded_vmcs->host_state.cr4 = cr4; - } - - vm_fail = __vmx_vcpu_run(vmx, (unsigned long *)&vcpu->arch.regs, - __vmx_vcpu_run_flags(vmx)); - - if (vmx->msr_autoload.host.nr) - vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, vmx->msr_autoload.host.nr); - if (vmx->msr_autoload.guest.nr) - vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, vmx->msr_autoload.guest.nr); - - if (vm_fail) { - u32 error = vmcs_read32(VM_INSTRUCTION_ERROR); - - preempt_enable(); - - trace_kvm_nested_vmenter_failed( - "early hardware check VM-instruction error: ", error); - WARN_ON_ONCE(error != VMXERR_ENTRY_INVALID_CONTROL_FIELD); - return 1; - } - - /* - * VMExit clears RFLAGS.IF and DR7, even on a consistency check. - */ - if (hw_breakpoint_active()) - set_debugreg(__this_cpu_read(cpu_dr7), 7); - local_irq_enable(); - preempt_enable(); - - /* - * A non-failing VMEntry means we somehow entered guest mode with - * an illegal RIP, and that's just the tip of the iceberg. There - * is no telling what memory has been modified or what state has - * been exposed to unknown code. Hitting this all but guarantees - * a (very critical) hardware issue. - */ - WARN_ON(!(vmcs_read32(VM_EXIT_REASON) & - VMX_EXIT_REASONS_FAILED_VMENTRY)); - - return 0; -} - #ifdef CONFIG_KVM_HYPERV static bool nested_get_evmcs_page(struct kvm_vcpu *vcpu) { @@ -3679,22 +3584,18 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu, &vmx->nested.pre_vmenter_ssp_tbl); /* - * Overwrite vmcs01.GUEST_CR3 with L1's CR3 if EPT is disabled *and* - * nested early checks are disabled. In the event of a "late" VM-Fail, - * i.e. a VM-Fail detected by hardware but not KVM, KVM must unwind its - * software model to the pre-VMEntry host state. When EPT is disabled, - * GUEST_CR3 holds KVM's shadow CR3, not L1's "real" CR3, which causes - * nested_vmx_restore_host_state() to corrupt vcpu->arch.cr3. Stuffing - * vmcs01.GUEST_CR3 results in the unwind naturally setting arch.cr3 to - * the correct value. Smashing vmcs01.GUEST_CR3 is safe because nested - * VM-Exits, and the unwind, reset KVM's MMU, i.e. vmcs01.GUEST_CR3 is - * guaranteed to be overwritten with a shadow CR3 prior to re-entering - * L1. Don't stuff vmcs01.GUEST_CR3 when using nested early checks as - * KVM modifies vcpu->arch.cr3 if and only if the early hardware checks - * pass, and early VM-Fails do not reset KVM's MMU, i.e. the VM-Fail - * path would need to manually save/restore vmcs01.GUEST_CR3. + * Overwrite vmcs01.GUEST_CR3 with L1's CR3 if EPT is disabled. In the + * event of a "late" VM-Fail, i.e. a VM-Fail detected by hardware but + * not KVM, KVM must unwind its software model to the pre-VM-Entry host + * state. When EPT is disabled, GUEST_CR3 holds KVM's shadow CR3, not + * L1's "real" CR3, which causes nested_vmx_restore_host_state() to + * corrupt vcpu->arch.cr3. Stuffing vmcs01.GUEST_CR3 results in the + * unwind naturally setting arch.cr3 to the correct value. Smashing + * vmcs01.GUEST_CR3 is safe because nested VM-Exits, and the unwind, + * reset KVM's MMU, i.e. vmcs01.GUEST_CR3 is guaranteed to be + * overwritten with a shadow CR3 prior to re-entering L1. */ - if (!enable_ept && !nested_early_check) + if (!enable_ept) vmcs_writel(GUEST_CR3, vcpu->arch.cr3); vmx_switch_vmcs(vcpu, &vmx->nested.vmcs02); @@ -3707,11 +3608,6 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu, return NVMX_VMENTRY_KVM_INTERNAL_ERROR; } - if (nested_vmx_check_vmentry_hw(vcpu)) { - vmx_switch_vmcs(vcpu, &vmx->vmcs01); - return NVMX_VMENTRY_VMFAIL; - } - if (nested_vmx_check_guest_state(vcpu, vmcs12, &entry_failure_code)) { exit_reason.basic = EXIT_REASON_INVALID_STATE; @@ -5176,12 +5072,10 @@ void __nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 vm_exit_reason, /* * The only expected VM-instruction error is "VM entry with * invalid control field(s)." Anything else indicates a - * problem with L0. And we should never get here with a - * VMFail of any type if early consistency checks are enabled. + * problem with L0. */ WARN_ON_ONCE(vmcs_read32(VM_INSTRUCTION_ERROR) != VMXERR_ENTRY_INVALID_CONTROL_FIELD); - WARN_ON_ONCE(nested_early_check); } /* |