Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932137AbdCUE2s (ORCPT ); Tue, 21 Mar 2017 00:28:48 -0400 Received: from mail-wm0-f49.google.com ([74.125.82.49]:36950 "EHLO mail-wm0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751727AbdCUE2q (ORCPT ); Tue, 21 Mar 2017 00:28:46 -0400 MIME-Version: 1.0 In-Reply-To: <20170320145808.GA23433@potion> References: <1490012745-10122-1-git-send-email-wanpeng.li@hotmail.com> <20170320145808.GA23433@potion> From: Wanpeng Li Date: Tue, 21 Mar 2017 12:28:44 +0800 Message-ID: Subject: Re: [PATCH] KVM: nVMX: Fix L2 guest crash when VPID is disabled on L0 To: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= Cc: "linux-kernel@vger.kernel.org" , kvm , Paolo Bonzini , Wanpeng Li 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-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id v2L4Spvq025684 Content-Length: 2751 Lines: 72 2017-03-20 22:58 GMT+08:00 Radim Krčmář : > 2017-03-20 05:25-0700, Wanpeng Li: >> From: Wanpeng Li >> >> L2 guest crash during boot if VPID is enabled on L1 and disabled on L0. This >> also can be catched by kvm-unit-tests/vmx.flat when VPID is disabled on L0. >> >> KVM: entry failed, hardware error 0x7 >> EAX=00000000 EBX=00000000 ECX=00000000 EDX=000306c3 >> ESI=00000000 EDI=00000000 EBP=00000000 ESP=00000000 >> EIP=0000fff0 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0 >> ES =0000 00000000 0000ffff 00009300 >> CS =f000 ffff0000 0000ffff 00009b00 >> SS =0000 00000000 0000ffff 00009300 >> DS =0000 00000000 0000ffff 00009300 >> FS =0000 00000000 0000ffff 00009300 >> GS =0000 00000000 0000ffff 00009300 >> LDT=0000 00000000 0000ffff 00008200 >> TR =0000 00000000 0000ffff 00008b00 >> GDT= 00000000 0000ffff >> IDT= 00000000 0000ffff >> CR0=60000010 CR2=00000000 CR3=00000000 CR4=00000000 >> DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000 >> DR6=00000000ffff0ff0 DR7=0000000000000400 >> EFER=0000000000000000 > > I couldn't reproduce the hardware error. Unit test just got #UD and > exited, which seems to be because KVM doesn't add the exec controls in > vmcs02. I fix this unit test #UD in v2 1/3, and the above crash in v2 2/3. > >> The enable_vpid sysfs perm parameter miss the 0 prefix, so the enable_vpid >> is failed to be disabled though vmcs_config bit is not set. This patch fixes >> it by utilizing S_IRUGO which includes 0 prefix instead. >> >> Cc: Paolo Bonzini >> Cc: Radim Krčmář >> Signed-off-by: Wanpeng Li >> --- >> arch/x86/kvm/vmx.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >> index 98e82ee..a7e4880 100644 >> --- a/arch/x86/kvm/vmx.c >> +++ b/arch/x86/kvm/vmx.c >> @@ -66,7 +66,7 @@ static const struct x86_cpu_id vmx_cpu_id[] = { >> MODULE_DEVICE_TABLE(x86cpu, vmx_cpu_id); >> >> static bool __read_mostly enable_vpid = 1; >> -module_param_named(vpid, enable_vpid, bool, 0444); >> +module_param_named(vpid, enable_vpid, bool, S_IRUGO); > > Aren't "0444" and "(00400 | 00040 | 00004)" the same number? > > I'm not convinced this patch fixes anything and I think we have two Yeah, maybe I'm too tired yesterday and more coffee is really appreciated. :) > options when approaching VPID: > 1) hide and forbid VPIDs in L1 if they are disabled on L0 > 2) expose VPID hardware to L1 regardless of L0 settings > > We treat other features like (1), because it simplifies implementation, > so I'd do the same for VPID ... Good point. Please review v2. :) Regards, Wanpeng Li