From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [RFC 0/6] Enlightened VMCS support for KVM on Hyper-V Date: Tue, 16 Jan 2018 15:27:33 +0100 Message-ID: References: <20180115173105.31845-1-vkuznets@redhat.com> <87inc2huux.fsf@vitty.brq.redhat.com> <87tvvlhplx.fsf@vitty.brq.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit 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 To: Vitaly Kuznetsov , David Hildenbrand Return-path: In-Reply-To: <87tvvlhplx.fsf@vitty.brq.redhat.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 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