From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934004AbdKCRNh (ORCPT ); Fri, 3 Nov 2017 13:13:37 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:16947 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933875AbdKCRNP (ORCPT ); Fri, 3 Nov 2017 13:13:15 -0400 Subject: Re: [PATCH v5 2/3] KVM: nVMX: Validate the IA32_BNDCFGS on nested VM-entry To: Wanpeng Li References: <1509670249-4907-1-git-send-email-wanpeng.li@hotmail.com> <1509670249-4907-2-git-send-email-wanpeng.li@hotmail.com> <0b1d82f7-2fc6-9fc0-15a4-3500413814bd@oracle.com> Cc: Paolo Bonzini , Radim Krcmar , kvm , "linux-kernel@vger.kernel.org" , Jim Mattson From: Krish Sadhukhan Message-ID: <7c2c39a3-8b24-e89a-1c67-385a5c6a2976@oracle.com> Date: Fri, 3 Nov 2017 10:13:08 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/02/2017 11:40 PM, Wanpeng Li wrote: > 2017-11-03 14:31 GMT+08:00 Krish Sadhukhan : >> >> On 11/02/2017 05:50 PM, Wanpeng Li wrote: >>> From: Wanpeng Li >>> >>> According to the SDM, if the "load IA32_BNDCFGS" VM-entry controls is 1, >>> the >>> following checks are performed on the field for the IA32_BNDCFGS MSR: >>> - Bits reserved in the IA32_BNDCFGS MSR must be 0. >>> - The linear address in bits 63:12 must be canonical. >>> >>> Reviewed-by: Konrad Rzeszutek Wilk >>> Cc: Paolo Bonzini >>> Cc: Radim Krčmář >>> Cc: Jim Mattson >>> Signed-off-by: Wanpeng Li >>> --- >>> v3 -> v4: >>> * simply condition >>> * use && instead of nested "if"s >>> >>> arch/x86/kvm/vmx.c | 5 +++++ >>> 1 file changed, 5 insertions(+) >>> >>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >>> index e6c8ffa..6cf3972 100644 >>> --- a/arch/x86/kvm/vmx.c >>> +++ b/arch/x86/kvm/vmx.c >>> @@ -10805,6 +10805,11 @@ static int check_vmentry_postreqs(struct kvm_vcpu >>> *vcpu, struct vmcs12 *vmcs12, >>> return 1; >>> } >>> + if (kvm_mpx_supported() && >>> + (is_noncanonical_address(vmcs12->guest_bndcfgs & >>> PAGE_MASK, vcpu) || >>> + (vmcs12->guest_bndcfgs & MSR_IA32_BNDCFGS_RSVD))) >>> + return 1; >>> + >>> return 0; >>> } >>> >> Hi Wanpeng, >> The SDM check is performed only when "load IA32_BNDCFGS" VM-entry control >> is 1. But vmx_mpx_supported() returns true when both "load IA32_BNDCFGS" and >> "store IA32_BNDCFGS" VM-entry controls are 1. Therefore your check is >> performed when both controls are 1. Did I miss something here ? > https://lkml.org/lkml/2017/11/2/748 Paolo hopes the simplification. > > Regards, > Wanpeng Li I got that simplification and your changes look good to me. However, I am still curious know the reason why vmx_mpx_supported() returns true only when both controls are true whereas the SDM states the following: "IA32_BNDCFGS (64 bits). This field is supported only on processors that support either the 1-setting of the “load IA32_BNDCFGS” VM-entry control or that of the “clear IA32_BNDCFGS” VM-exit control." Thanks, Krish