diff options
| -rw-r--r-- | arch/x86/kvm/svm/nested.c | 2 | ||||
| -rw-r--r-- | arch/x86/kvm/vmx/nested.c | 11 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.h | 18 |
3 files changed, 21 insertions, 10 deletions
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 834b67672d50..6cd2cf7f6f68 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -1041,6 +1041,8 @@ int nested_svm_vmexit(struct vcpu_svm *svm) nested_svm_copy_common_state(svm->nested.vmcb02.ptr, svm->vmcb01.ptr); + kvm_nested_vmexit_handle_ibrs(vcpu); + svm_switch_vmcb(svm, &svm->vmcb01); /* diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index e073e3008b16..ebeb183270cf 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -5020,16 +5020,7 @@ void __nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 vm_exit_reason, vmx_switch_vmcs(vcpu, &vmx->vmcs01); - /* - * If IBRS is advertised to the vCPU, KVM must flush the indirect - * branch predictors when transitioning from L2 to L1, as L1 expects - * hardware (KVM in this case) to provide separate predictor modes. - * Bare metal isolates VMX root (host) from VMX non-root (guest), but - * doesn't isolate different VMCSs, i.e. in this case, doesn't provide - * separate modes for L2 vs L1. - */ - if (guest_cpu_cap_has(vcpu, X86_FEATURE_SPEC_CTRL)) - indirect_branch_prediction_barrier(); + kvm_nested_vmexit_handle_ibrs(vcpu); /* Update any VMCS fields that might have changed while L2 ran */ vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, vmx->msr_autoload.host.nr); diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index 88a9475899c8..832f0faf4779 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -121,6 +121,24 @@ static inline void kvm_leave_nested(struct kvm_vcpu *vcpu) kvm_x86_ops.nested_ops->leave_nested(vcpu); } +/* + * If IBRS is advertised to the vCPU, KVM must flush the indirect branch + * predictors when transitioning from L2 to L1, as L1 expects hardware (KVM in + * this case) to provide separate predictor modes. Bare metal isolates the host + * from the guest, but doesn't isolate different guests from one another (in + * this case L1 and L2). The exception is if bare metal supports same mode IBRS, + * which offers protection within the same mode, and hence protects L1 from L2. + */ +static inline void kvm_nested_vmexit_handle_ibrs(struct kvm_vcpu *vcpu) +{ + if (cpu_feature_enabled(X86_FEATURE_AMD_IBRS_SAME_MODE)) + return; + + if (guest_cpu_cap_has(vcpu, X86_FEATURE_SPEC_CTRL) || + guest_cpu_cap_has(vcpu, X86_FEATURE_AMD_IBRS)) + indirect_branch_prediction_barrier(); +} + static inline bool kvm_vcpu_has_run(struct kvm_vcpu *vcpu) { return vcpu->arch.last_vmentry_cpu != -1; |