Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751097AbeAPO2f (ORCPT + 1 other); Tue, 16 Jan 2018 09:28:35 -0500 Received: from mx1.redhat.com ([209.132.183.28]:57828 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750779AbeAPO2d (ORCPT ); Tue, 16 Jan 2018 09:28:33 -0500 Subject: Re: [RFC 0/6] Enlightened VMCS support for KVM on Hyper-V To: Vitaly Kuznetsov , David Hildenbrand Cc: Wanpeng Li , kvm , the arch/x86 maintainers , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , "Michael Kelley (EOSG)" , Mohammed Gamal , Cathy Avery , Bandan Das , linux-kernel@vger.kernel.org References: <20180115173105.31845-1-vkuznets@redhat.com> <87inc2huux.fsf@vitty.brq.redhat.com> <87tvvlhplx.fsf@vitty.brq.redhat.com> From: Paolo Bonzini Message-ID: Date: Tue, 16 Jan 2018 15:27:33 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <87tvvlhplx.fsf@vitty.brq.redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Tue, 16 Jan 2018 14:28:28 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On 16/01/2018 14:58, Vitaly Kuznetsov wrote: >> Haven't looked into the details, but we have to watch out for other >> VCPUs trying to modify that vmcs12. >> >> Basically because other VCPUs could try to modify values in vmcs12 while >> we are currently building vmcs02. Nasty races could result in us copying >> stuff (probably unchecked) into vmcs02 and therefore running something >> that was not intended. >> > I don't think we share VMCS among vCPUs, do we? VMCS is just memory, so who knows what a malicious L1 guest will do. But for vmread/vmwrite we can go through hypervisor memory, for enlightened VMCS we cannot. Paolo