Stop clearing TLB_CONTROL when preparing the control area of vmcb02, as this potentially undoes pending TLB flushes for L2 (e.g. through KVM_REQ_TLB_FLUSH while L1 is running), and remove the associated TODO comment. This is currently harmless, because nested_svm_entry_tlb_flush() always requests KVM_REQ_TLB_FLUSH_CURRENT on nested VM-Enter, which sets TLB_CONTROL again before L2 is actually run. However, always flushing will soon go away with proper TLB handling for L2, at which point always clearing TLB_CONTROL would be a bug. Clearing TLB_CONTROL on nested VM-Enter was probably done because TLB_CONTROL is not cleared by the CPU on VM-Exit. However, KVM always clears TLB_CONTROL in the active VMCB after a successful VMRUN. Hence, at nested VM-Enter, TLB_CONTROL in vmcb02 can only be non-zero if a TLB flush is queued for L2 while L1 is running (i.e. KVM_REQ_TLB_FLUSH), and that should never be ignored. Signed-off-by: Yosry Ahmed --- arch/x86/kvm/svm/nested.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 8e4686b0d603a..738ec1f2ec869 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -723,12 +723,7 @@ static void nested_svm_entry_tlb_flush(struct kvm_vcpu *vcpu) kvm_make_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu); } - /* - * TODO: optimize unconditional TLB flush/MMU sync. A partial list of - * things to fix before this can be conditional: - * - * - Don't crush a pending TLB flush in vmcb02 on nested VMRUN - */ + /* TODO: optimize unconditional TLB flush/MMU sync */ kvm_make_request(KVM_REQ_MMU_SYNC, vcpu); kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu); } @@ -975,9 +970,6 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm) vmcb02->control.asid = svm->nested.asid02; - /* Overwritten later if necessary. */ - vmcb_clr_flush_asid(vmcb02); - /* Use vmcb01 MMU and format if guest does not use nNPT */ if (nested_npt_enabled(svm)) { vmcb02->control.misc_ctl &= ~SVM_MISC_ENABLE_GMET; -- 2.56.0.385.gd3acb90ef8-goog