From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kashyap Chamarthy Subject: Re: [PATCH RESEND] KVM: nVMX: mask unrestricted_guest if disabled on L0 Date: Tue, 17 Mar 2015 19:43:15 +0100 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-Transfer-Encoding: QUOTED-PRINTABLE Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Paolo Bonzini , Marcelo Tosatti , stable@vger.kernel.org To: Radim =?utf-8?B?S3LEjW3DocWZ?= Return-path: Content-Disposition: inline In-Reply-To: <1426597352-4115-1-git-send-email-rkrcmar@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Tue, Mar 17, 2015 at 02:02:32PM +0100, Radim Kr=C4=8Dm=C3=A1=C5=99 w= rote: > If EPT was enabled, unrestricted_guest was allowed in L1 regardless o= f > L0. L1 triple faulted when running L2 guest that required emulation. >=20 > 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] () >=20 > Prevent this scenario by masking SECONDARY_EXEC_UNRESTRICTED_GUEST wh= en > the host doesn't have it enabled. >=20 > Fixes: 78051e3b7e35 ("KVM: nVMX: Disable unrestricted mode if ept=3D0= ") > 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 --=20 /kashyap > Signed-off-by: Radim Kr=C4=8Dm=C3=A1=C5=99 > --- > The resend Cc'd stable, as recommended by Bandan, and added Tested-b= y. >=20 > arch/x86/kvm/vmx.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) >=20 > 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 v= cpu_vmx *vmx) > if (enable_ept) { > /* nested EPT: emulate EPT also to L1 */ > vmx->nested.nested_vmx_secondary_ctls_high |=3D > - SECONDARY_EXEC_ENABLE_EPT | > - SECONDARY_EXEC_UNRESTRICTED_GUEST; > + SECONDARY_EXEC_ENABLE_EPT; > vmx->nested.nested_vmx_ept_caps =3D 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 =3D 0; > =20 > + if (enable_unrestricted_guest) > + vmx->nested.nested_vmx_secondary_ctls_high |=3D > + SECONDARY_EXEC_UNRESTRICTED_GUEST; > + > /* miscellaneous data */ > rdmsr(MSR_IA32_VMX_MISC, > vmx->nested.nested_vmx_misc_low, > --=20 > 2.3.2 >=20