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IIUC, kvm_apic_update_hwapic_isr() >> guarantees an update to VMCS01's SVI even if the vCPU is in guest mode. >> >> And there is already a check against apicv_active right below. So, to be >> concise, how about: >> >> if (!apic->apicv_active) >> kvm_make_request(KVM_REQ_EVENT, vcpu); >> else >> kvm_apic_update_hwapic_isr(vcpu); > >Thank you very much for reminder. > >I missed the scenario when vCPU is in L2. The __nested_vmx_vmexit() will not >call kvm_apic_update_hwapic_isr() unless 'update_vmcs01_hwapic_isr' is set to true. > >However, can I remove the below WARN_ON_ONCE introduced by the commit >04bc93cf49d1 ("KVM: nVMX: Defer SVI update to vmcs01 on EOI when L2 is active >w/o VID")? > >Now we need to call vmx_hwapic_isr_update() when the vCPU is running with vmcs12 >VID configured. > >diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c >index f87c216d976d..d263dbf0b917 100644 >--- a/arch/x86/kvm/vmx/vmx.c >+++ b/arch/x86/kvm/vmx/vmx.c >@@ -6878,15 +6878,6 @@ void vmx_hwapic_isr_update(struct kvm_vcpu *vcpu, int >max_isr) > * VM-Exit, otherwise L1 with run with a stale SVI. > */ > if (is_guest_mode(vcpu)) { >- /* >- * KVM is supposed to forward intercepted L2 EOIs to L1 if VID >- * is enabled in vmcs12; as above, the EOIs affect L2's vAPIC. >- * Note, userspace can stuff state while L2 is active; assert >- * that VID is disabled if and only if the vCPU is in KVM_RUN >- * to avoid false positives if userspace is setting APIC state. >- */ >- WARN_ON_ONCE(vcpu->wants_to_run && >- nested_cpu_has_vid(get_vmcs12(vcpu))); Thanks for testing this. I think it is fine to remove it. The warning produced some false positives when added. That's why we have the vcpu->wants_to_run check here. Now that we have new false positives; the check is less useful than expected. But let's see what Sean thinks about this. A side topic: I am not quite sure how vmx_refresh_apicv_exec_ctrl() works for the nested case. If a KVM_REQ_APICV_UPDATE event is pending, __kvm_vcpu_update_apicv() is called to update VMCS controls. If the vCPU is in a nested case, vmcs01 isn't updated immediately. Instead, the update is delayed by setting the update_vmcs01_apicv_status flag and another KVM_REQ_APICV_UPDATE request is queued to do the update after the nested VM exits. So, __kvm_vcpu_update_apicv() gets called again. My theory is that the second call doesn't update vmcs01 either because the "if (apic->apicv_active == activate)" condition becomes true and so vmx_refresh_apicv_exec_ctrl() isn't called again. > to_vmx(vcpu)->nested.update_vmcs01_hwapic_isr = true; > return; > } >