From 72e9cbdb43384ceacc49e2fb6b8c8fb7c5988778 Mon Sep 17 00:00:00 2001 From: Ladi Prosek Date: Wed, 11 Oct 2017 16:54:43 +0200 Subject: [PATCH] KVM: nVMX: fix SMI injection in guest mode Entering SMM while running in guest mode wasn't working very well because several pieces of the vcpu state were left set up for nested operation. Some of the issues observed: * L1 was getting unexpected VM exits (using L1 interception controls but running in SMM execution environment) * SMM handler couldn't write to vmx_set_cr4 because of incorrect validity checks predicated on nested.vmxon * MMU was confused (walk_mmu was still set to nested_mmu) Intel SDM actually prescribes the logical processor to "leave VMX operation" upon entering SMM in 34.14.1 Default Treatment of SMI Delivery. What we need to do is basically get out of guest mode and set nested.vmxon to false for the duration of SMM. All this completely transparent to L1, i.e. L1 is not given control and no L1 observable state changes. To avoid code duplication this commit takes advantage of the existing nested vmexit and run functionality, perhaps at the cost of efficiency. To get out of guest mode, nested_vmx_vmexit with exit_reason == -1 is called, a trick already used in vmx_leave_nested. Re-entering is cleaner, using enter_vmx_non_root_mode. This commit fixes running Windows Server 2016 with Hyper-V enabled in a VM with OVMF firmware (OVMF_CODE-need-smm.fd). Signed-off-by: Ladi Prosek Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx.c | 60 +++++++++++++++++++++++++++++++++++++--------- 1 file changed, 49 insertions(+), 11 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 6f4e29b343a8..c460b0b439d3 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -486,6 +486,14 @@ struct nested_vmx { u64 nested_vmx_cr4_fixed1; u64 nested_vmx_vmcs_enum; u64 nested_vmx_vmfunc_controls; + + /* SMM related state */ + struct { + /* in VMX operation on SMM entry? */ + bool vmxon; + /* in guest mode on SMM entry? */ + bool guest_mode; + } smm; }; #define POSTED_INTR_ON 0 @@ -11401,8 +11409,11 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason, leave_guest_mode(vcpu); if (likely(!vmx->fail)) { - prepare_vmcs12(vcpu, vmcs12, exit_reason, exit_intr_info, - exit_qualification); + if (exit_reason == -1) + sync_vmcs12(vcpu, vmcs12); + else + prepare_vmcs12(vcpu, vmcs12, exit_reason, exit_intr_info, + exit_qualification); if (nested_vmx_store_msr(vcpu, vmcs12->vm_exit_msr_store_addr, vmcs12->vm_exit_msr_store_count)) @@ -11466,7 +11477,7 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason, */ kvm_make_request(KVM_REQ_APIC_PAGE_RELOAD, vcpu); - if (enable_shadow_vmcs) + if (enable_shadow_vmcs && exit_reason != -1) vmx->nested.sync_shadow_vmcs = true; /* in case we halted in L2 */ @@ -11490,12 +11501,13 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason, INTR_INFO_VALID_MASK | INTR_TYPE_EXT_INTR; } - trace_kvm_nested_vmexit_inject(vmcs12->vm_exit_reason, - vmcs12->exit_qualification, - vmcs12->idt_vectoring_info_field, - vmcs12->vm_exit_intr_info, - vmcs12->vm_exit_intr_error_code, - KVM_ISA_VMX); + if (exit_reason != -1) + trace_kvm_nested_vmexit_inject(vmcs12->vm_exit_reason, + vmcs12->exit_qualification, + vmcs12->idt_vectoring_info_field, + vmcs12->vm_exit_intr_info, + vmcs12->vm_exit_intr_error_code, + KVM_ISA_VMX); load_vmcs12_host_state(vcpu, vmcs12); @@ -11920,18 +11932,44 @@ static void vmx_setup_mce(struct kvm_vcpu *vcpu) static int vmx_smi_allowed(struct kvm_vcpu *vcpu) { + /* we need a nested vmexit to enter SMM, postpone if run is pending */ + if (to_vmx(vcpu)->nested.nested_run_pending) + return 0; return 1; } static int vmx_pre_enter_smm(struct kvm_vcpu *vcpu, char *smstate) { - /* TODO: Implement */ + struct vcpu_vmx *vmx = to_vmx(vcpu); + + vmx->nested.smm.guest_mode = is_guest_mode(vcpu); + if (vmx->nested.smm.guest_mode) + nested_vmx_vmexit(vcpu, -1, 0, 0); + + vmx->nested.smm.vmxon = vmx->nested.vmxon; + vmx->nested.vmxon = false; return 0; } static int vmx_pre_leave_smm(struct kvm_vcpu *vcpu, u64 smbase) { - /* TODO: Implement */ + struct vcpu_vmx *vmx = to_vmx(vcpu); + int ret; + + if (vmx->nested.smm.vmxon) { + vmx->nested.vmxon = true; + vmx->nested.smm.vmxon = false; + } + + if (vmx->nested.smm.guest_mode) { + vcpu->arch.hflags &= ~HF_SMM_MASK; + ret = enter_vmx_non_root_mode(vcpu, false); + vcpu->arch.hflags |= HF_SMM_MASK; + if (ret) + return ret; + + vmx->nested.smm.guest_mode = false; + } return 0; } -- 2.30.2