From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Egger Subject: Re: why xen use x86_emulation() in page_fault Date: Thu, 13 Oct 2011 14:21:48 +0200 Message-ID: <4E96D7DC.8010807@amd.com> References: <20111011081829.GB88076@ocelot.phlegethon.org> <20111011112900.GF88076@ocelot.phlegethon.org> <20111011122107.GG88076@ocelot.phlegethon.org> <20111013114752.GG44937@ocelot.phlegethon.org> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20111013114752.GG44937@ocelot.phlegethon.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Tim Deegan Cc: cc Luit , "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org On 10/13/11 13:47, Tim Deegan wrote: > At 21:07 +0800 on 11 Oct (1318367233), cc Luit wrote: >>>> Why don't you just use EPT/NPT instead of shadow pagetables? That code >>>> is a lot simpler and the end result is easier to validate than shadow >>>> pagetables are. Is it particularly important to support shadow >>> pagetables? >>> >> yeah, we have consider that, and of course the EPT is much more convenient, >> BTW, do you know is there any simulator that can well support EPT of xen? >> the shadow page's problem is a little relevent to the selection of >> simulator~ > > There's experimental support in Xen itself for running a hypervisor > inside a HVM guest. On AMD, that includes (and indeed requires) NPT in > the guest hypervisor. Not quite right: guest hypervisor can use NPT but this is not required. It may use shadow paging. But an AMD cpu with NPT capability is required since shadow-on-shadow is not supported. > Unfortunately, on Intel it does not include EPT. > > There may be some other simulators that have EPT/NPT - I don't know. > > Cheers, > > Tim. -- ---to satisfy European Law for business letters: Advanced Micro Devices GmbH Einsteinring 24, 85689 Dornach b. Muenchen Geschaeftsfuehrer: Alberto Bozzo, Andrew Bowd Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen Registergericht Muenchen, HRB Nr. 43632