TLB_CONTROL is reset to TLB_CONTROL_DO_NOTHING on nested transitions to L2. This is unnecessary because it should always be TLB_CONTROL_DO_NOTHING at this point. The flow for setting TLB_CONTROL is as follows: 1. In vcpu_enter_guest(), servicing a TLB flush request may set it to TLB_CONTROL_FLUSH_ASID in svm_flush_tlb_asid(). 2. In svm_vcpu_run() -> pre_svm_run(), it may get upgraded to TLB_CONTROL_FLUSH_ALL_ASID when assigning a new ASID. 3. In svm_cpu_run(), it gets reset to TLB_CONTROL_DO_NOTHING after the guest is run. Hence, TLB_CONTROL is reset after each run and there is no need to do it again on every nested transition to L2. There is a TODO in nested_svm_transition_tlb_flush() about this reset crushing pending TLB flushes. Remove it, as the reset is not really crushing anything as explained above. Signed-off-by: Yosry Ahmed <yosry.ahmed@xxxxxxxxx> --- arch/x86/kvm/svm/nested.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 12bb391884299..8e40ff21f7353 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -512,12 +512,7 @@ static void nested_svm_entry_tlb_flush(struct kvm_vcpu *vcpu) svm->nested.last_asid = svm->nested.ctl.asid; 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); } @@ -536,7 +531,7 @@ static void nested_svm_exit_tlb_flush(struct kvm_vcpu *vcpu) if (svm->nested.ctl.tlb_ctl == TLB_CONTROL_FLUSH_ALL_ASID) kvm_make_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu); - /* See nested_svm_entry_tlb_flush() */ + /* TODO: optimize unconditional TLB flush/MMU sync */ kvm_make_request(KVM_REQ_MMU_SYNC, vcpu); kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu); } @@ -717,9 +712,6 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm, /* Done at vmrun: asid. */ - /* Also overwritten later if necessary. */ - svm_clear_tlb_ctl_flush(vmcb02); - /* nested_cr3. */ if (nested_npt_enabled(svm)) nested_svm_init_mmu_context(vcpu); -- 2.48.1.362.g079036d154-goog
