Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754727AbbB0I4a (ORCPT ); Fri, 27 Feb 2015 03:56:30 -0500 Received: from mail-lb0-f181.google.com ([209.85.217.181]:46816 "EHLO mail-lb0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752093AbbB0I42 (ORCPT ); Fri, 27 Feb 2015 03:56:28 -0500 MIME-Version: 1.0 In-Reply-To: <20150215062755.GA2603@ywang-linux> References: <1422979097-2203-1-git-send-email-fanwenyi0529@gmail.com> <20150215062755.GA2603@ywang-linux> From: Wincy Van Date: Fri, 27 Feb 2015 16:56:06 +0800 Message-ID: Subject: Re: [PATCH resend v5 6/6] KVM: nVMX: Enable nested posted interrupt processing To: Yong Wang Cc: Paolo Bonzini , "gleb@kernel.org" , "Zhang, Yang Z" , Wanpeng Li , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Jan Kiszka , mtosatti@redhat.com Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2566 Lines: 77 On Sun, Feb 15, 2015 at 2:27 PM, Yong Wang wrote: > > Wincy, our QA found regressions with this patch that 64bit L2 linux guest > fails to boot up when running nested kvm on kvm. > > Environment: > ------------ > Host OS (ia32/ia32e/IA64):ia32e > Guest OS (ia32/ia32e/IA64):ia32e > Guest OS Type (Linux/Windows):Linux > kvm.git Commit:6557bada461afeaa920a189fae2cff7c8fdce39f > qemu.kvm Commit:5c697ae74170d43928cb185f5ac1a9058adcae0b > Host Kernel Version:3.19.0-rc3 > Hardware:Ivytown_EP, Haswell_EP > > > Bug detailed description: > -------------------------- > create 64bit linux guest as L2 guest, the guest boot up fail > > note: > 1. create a 32bit linux guest as L2 guest, the guest boots up fine. > 2. create a 64bit windows guest as L2 guest, the guest boots up fine. > 3. this should be a kernel bug: > kvm + qemu = result > 6557bada + 5c697ae7 = bad > 8fff5e37 + 5c697ae7 = good > > Reproduce steps: > ---------------- > 1 create L1 guest: > qemu-system-x86_64 -enable-kvm -m 8G -smp 4 -net nic,macaddr=00:12:31:34:51:31 -net tap,script=/etc/kvm/qemu-ifup nested-kvm.qcow -cpu host > > 2. create L2 guest > qemu-system-x86_64 -enable-kvm -m 2G -smp 2 -net none rhel6u5.qcow > > Current result: > ---------------- > create 64bit linux guest as L2 guest, the guest boots up fail > > Expected result: > ---------------- > create 64bit linux guest as L2 guest, the guest boots up fine > > Please take a look. > Yong, according to the logs, I found that L1 may have disabled x2apic, and the MSR_BITMAP field will be modified by following vmx_set_efer in prepare_vmcs02. So I think we can fix this issue by: diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index f7b20b4..f6e3457 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2168,7 +2168,10 @@ static void vmx_set_msr_bitmap(struct kvm_vcpu *vcpu) { unsigned long *msr_bitmap; - if (irqchip_in_kernel(vcpu->kvm) && apic_x2apic_mode(vcpu->arch.apic)) { + if (is_guest_mode(vcpu)) + msr_bitmap = vmx_msr_bitmap_nested; + else if (irqchip_in_kernel(vcpu->kvm) && + apic_x2apic_mode(vcpu->arch.apic)) { if (is_long_mode(vcpu)) msr_bitmap = vmx_msr_bitmap_longmode_x2apic; else Thanks, Wincy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/