From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: [PATCH v1 2/2] KVM: VMX: always require WB memory type for EPT Date: Thu, 10 Aug 2017 14:30:56 -0400 Message-ID: <20170810183056.GY2547@char.us.oracle.com> References: <20170810133512.13442-1-david@redhat.com> <20170810133512.13442-3-david@redhat.com> <4e7e54e0-87fe-26ea-c90b-1472aa973398@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Hildenbrand , kvm@vger.kernel.org, Radim =?utf-8?B?S3LEjW3DocWZ?= , Bandan Das To: Paolo Bonzini Return-path: Received: from aserp1040.oracle.com ([141.146.126.69]:23670 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752639AbdHJSbM (ORCPT ); Thu, 10 Aug 2017 14:31:12 -0400 Content-Disposition: inline In-Reply-To: <4e7e54e0-87fe-26ea-c90b-1472aa973398@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Thu, Aug 10, 2017 at 04:42:02PM +0200, Paolo Bonzini wrote: > On 10/08/2017 15:35, David Hildenbrand wrote: > > We already always set that type but don't check if it is supported. Also > > for nVMX, we only support WB for now. Let's just require it. > > > > Signed-off-by: David Hildenbrand > > It may only happen on a broken nested hypervisor, so the patch is okay. Is there one in the wild? > > Paolo > > > --- > > arch/x86/kvm/vmx.c | 9 +++++++-- > > 1 file changed, 7 insertions(+), 2 deletions(-) > > > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > > index f6638ed..023c6dc 100644 > > --- a/arch/x86/kvm/vmx.c > > +++ b/arch/x86/kvm/vmx.c > > @@ -1200,6 +1200,11 @@ static inline bool cpu_has_vmx_ept_4levels(void) > > return vmx_capability.ept & VMX_EPT_PAGE_WALK_4_BIT; > > } > > > > +static inline bool cpu_has_vmx_ept_mt_wb(void) > > +{ > > + return vmx_capability.ept & VMX_EPTP_WB_BIT; > > +} > > + > > static inline bool cpu_has_vmx_ept_ad_bits(void) > > { > > return vmx_capability.ept & VMX_EPT_AD_BIT; > > @@ -4302,7 +4307,6 @@ static u64 construct_eptp(struct kvm_vcpu *vcpu, unsigned long root_hpa) > > { > > u64 eptp = VMX_EPTP_MT_WB | VMX_EPTP_PWL_4; > > > > - /* TODO write the value reading from MSR */ > > if (enable_ept_ad_bits && > > (!is_guest_mode(vcpu) || nested_ept_ad_enabled(vcpu))) > > eptp |= VMX_EPTP_AD_ENABLE_BIT; > > @@ -6638,7 +6642,8 @@ static __init int hardware_setup(void) > > init_vmcs_shadow_fields(); > > > > if (!cpu_has_vmx_ept() || > > - !cpu_has_vmx_ept_4levels()) { > > + !cpu_has_vmx_ept_4levels() || > > + !cpu_has_vmx_ept_mt_wb()) { > > enable_ept = 0; > > enable_unrestricted_guest = 0; > > enable_ept_ad_bits = 0; > > >