Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932189AbWHVRQe (ORCPT ); Tue, 22 Aug 2006 13:16:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932238AbWHVRQe (ORCPT ); Tue, 22 Aug 2006 13:16:34 -0400 Received: from mailout1.vmware.com ([65.113.40.130]:7345 "EHLO mailout1.vmware.com") by vger.kernel.org with ESMTP id S932189AbWHVRQd (ORCPT ); Tue, 22 Aug 2006 13:16:33 -0400 Message-ID: <44EB3BF0.3040805@vmware.com> Date: Tue, 22 Aug 2006 10:16:32 -0700 From: Zachary Amsden User-Agent: Thunderbird 1.5.0.5 (X11/20060719) MIME-Version: 1.0 To: Andi Kleen Cc: virtualization@lists.osdl.org, Alan Cox , Jeremy Fitzhardinge , Andrew Morton , Chris Wright , Linux Kernel Mailing List Subject: Re: [PATCH] paravirt.h References: <1155202505.18420.5.camel@localhost.localdomain> <44DB7596.6010503@goop.org> <1156254965.27114.17.camel@localhost.localdomain> <200608221544.26989.ak@muc.de> In-Reply-To: <200608221544.26989.ak@muc.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1326 Lines: 35 Andi Kleen wrote: > I don't see why paravirt ops is that much more sensitive > than most other kernel code. > > >> It would be a lot safer if we could have the struct paravirt_ops in >> protected read-only const memory space, set it up in the core kernel >> early on in boot when we play "guess todays hypervisor" and then make >> sure it stays in read only (even to kernel) space. >> > > By default we don't make anything read only because that would > mess up the 2MB kernel mapping. > > In general i don't think making select code in the kernel > read only is a good idea, because as long as you don't > protect everything including stacks etc. there will be always > attack points where supposedly protected code relies > on unprotected state. If someone can write to kernel > memory you already lost. > > And it adds TLB pressure. > And it doesn't work for VMI or lhype, both of which might modify paravirt_ops way later in the boot process, when loaded as a module. Where did this conversation come from? I don't see it on any list I'm subscribed to. Zach - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/