From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752398AbeBXAj0 (ORCPT ); Fri, 23 Feb 2018 19:39:26 -0500 Received: from aserp2130.oracle.com ([141.146.126.79]:50908 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751547AbeBXAjY (ORCPT ); Fri, 23 Feb 2018 19:39:24 -0500 MIME-Version: 1.0 Message-ID: <764f4da9-2d0c-41cf-a4a4-d9b3bf3447c2@default> Date: Fri, 23 Feb 2018 16:39:21 -0800 (PST) From: Liran Alon To: Cc: , Subject: Re: [PATCH] KVM: x86: move LAPIC initialization after VMCS creation X-Mailer: Zimbra on Oracle Beehive Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8813 signatures=668678 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=1 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1711220000 definitions=main-1802240006 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id w1O0dW82016771 ----- pbonzini@redhat.com wrote: > The initial reset of the local APIC is performed before the VMCS has > been > created, but it tries to do a vmwrite: > > vmwrite error: reg 810 value 4a00 (err 18944) > CPU: 54 PID: 38652 Comm: qemu-kvm Tainted: G W I > 4.16.0-0.rc2.git0.1.fc28.x86_64 #1 > Hardware name: Intel Corporation S2600CW/S2600CW, BIOS > SE5C610.86B.01.01.0003.090520141303 09/05/2014 > Call Trace: > vmx_set_rvi [kvm_intel] > vmx_hwapic_irr_update [kvm_intel] > kvm_lapic_reset [kvm] > kvm_create_lapic [kvm] > kvm_arch_vcpu_init [kvm] > kvm_vcpu_init [kvm] > vmx_create_vcpu [kvm_intel] > kvm_vm_ioctl [kvm] > > Move it later, after the VMCS has been created. > > Fixes: 851c1a18c5412fd321e387cfe60739387cdbf37d > Cc: Liran Alon > Signed-off-by: Paolo Bonzini > --- > arch/x86/kvm/lapic.c | 1 - > arch/x86/kvm/x86.c | 1 + > 2 files changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > index 924ac8ce9d50..cc5fe7a50dde 100644 > --- a/arch/x86/kvm/lapic.c > +++ b/arch/x86/kvm/lapic.c > @@ -2165,7 +2165,6 @@ int kvm_create_lapic(struct kvm_vcpu *vcpu) > */ > vcpu->arch.apic_base = MSR_IA32_APICBASE_ENABLE; > static_key_slow_inc(&apic_sw_disabled.key); /* sw disabled at reset > */ > - kvm_lapic_reset(vcpu, false); > kvm_iodevice_init(&apic->dev, &apic_mmio_ops); > > return 0; > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index c8a0b545ac20..ca90d9515137 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -7975,6 +7975,7 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu) > kvm_vcpu_mtrr_init(vcpu); > vcpu_load(vcpu); > kvm_vcpu_reset(vcpu, false); > + kvm_lapic_reset(vcpu, false); > kvm_mmu_setup(vcpu); > vcpu_put(vcpu); > return 0; > -- > 1.8.3.1 I agree with the bug and the fix. It makes sense to reset LAPIC in the same place other components are reset rather than in it's creation. However, I failed to understand why you mention it fixes commit: 851c1a18c541 ("KVM: nVMX: Fix injection to L2 when L1 don't intercept external-interrupts") Before and after that commit, vmx_hwapic_irr_update() did exactly the same because is_guest_mode(vcpu)==false at this point. Therefore, vmx_hwapic_irr_update() has always just called vmx_set_rvi() which has not changed in that commit. It seems to me that the commit which introduced this issue is actually: 4191db26b714 ("KVM: x86: Update APICv on APIC reset") What am I missing? -Liran