From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932800AbbCQSn2 (ORCPT ); Tue, 17 Mar 2015 14:43:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60840 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932324AbbCQSnX (ORCPT ); Tue, 17 Mar 2015 14:43:23 -0400 Date: Tue, 17 Mar 2015 19:43:15 +0100 From: Kashyap Chamarthy To: Radim =?utf-8?B?S3LEjW3DocWZ?= Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Paolo Bonzini , Marcelo Tosatti , stable@vger.kernel.org Subject: Re: [PATCH RESEND] KVM: nVMX: mask unrestricted_guest if disabled on L0 Message-ID: <20150317184315.GP31340@tesla.redhat.com> References: <1426597352-4115-1-git-send-email-rkrcmar@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1426597352-4115-1-git-send-email-rkrcmar@redhat.com> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 17, 2015 at 02:02:32PM +0100, Radim Krčmář wrote: > If EPT was enabled, unrestricted_guest was allowed in L1 regardless of > L0. L1 triple faulted when running L2 guest that required emulation. > > Another side effect was 'WARN_ON_ONCE(vmx->nested.nested_run_pending)' > in L0's dmesg: > WARNING: CPU: 0 PID: 0 at arch/x86/kvm/vmx.c:9190 nested_vmx_vmexit+0x96e/0xb00 [kvm_intel] () > > Prevent this scenario by masking SECONDARY_EXEC_UNRESTRICTED_GUEST when > the host doesn't have it enabled. > > Fixes: 78051e3b7e35 ("KVM: nVMX: Disable unrestricted mode if ept=0") > Cc: stable@vger.kernel.org > Tested-By: Kashyap Chamarthy Thanks Radim, for resending it. I was trying to find it in one of the recent pull requests. :-) Just for forerence, test confirmation: http://article.gmane.org/gmane.comp.emulators.kvm.devel/133075 Complete thread related to this topic: http://thread.gmane.org/gmane.comp.emulators.kvm.devel/132863 -- /kashyap > Signed-off-by: Radim Krčmář > --- > The resend Cc'd stable, as recommended by Bandan, and added Tested-by. > > arch/x86/kvm/vmx.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 10a481b7674d..ae4f6d35d19c 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -2479,8 +2479,7 @@ static void nested_vmx_setup_ctls_msrs(struct vcpu_vmx *vmx) > if (enable_ept) { > /* nested EPT: emulate EPT also to L1 */ > vmx->nested.nested_vmx_secondary_ctls_high |= > - SECONDARY_EXEC_ENABLE_EPT | > - SECONDARY_EXEC_UNRESTRICTED_GUEST; > + SECONDARY_EXEC_ENABLE_EPT; > vmx->nested.nested_vmx_ept_caps = VMX_EPT_PAGE_WALK_4_BIT | > VMX_EPTP_WB_BIT | VMX_EPT_2MB_PAGE_BIT | > VMX_EPT_INVEPT_BIT; > @@ -2494,6 +2493,10 @@ static void nested_vmx_setup_ctls_msrs(struct vcpu_vmx *vmx) > } else > vmx->nested.nested_vmx_ept_caps = 0; > > + if (enable_unrestricted_guest) > + vmx->nested.nested_vmx_secondary_ctls_high |= > + SECONDARY_EXEC_UNRESTRICTED_GUEST; > + > /* miscellaneous data */ > rdmsr(MSR_IA32_VMX_MISC, > vmx->nested.nested_vmx_misc_low, > -- > 2.3.2 >