From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ryan Harper Subject: Re: [RFC][PATCH] ignore set_cr3 GP fault in non-pae mode Date: Tue, 18 Sep 2007 17:03:08 -0500 Message-ID: <20070918220308.GF7519@us.ibm.com> References: <20070918190516.GC7519@us.ibm.com> <46F023D8.90905@codemonkey.ws> <97D612E30E1F88419025B06CB4CF1BE1037F9013@scsmsx412.amr.corp.intel.com> <20070918212509.GE7519@us.ibm.com> <1190152700.8353.14.camel@bodhitayantram.eng.vmware.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, Ryan Harper To: Zachary Amsden Return-path: Content-Disposition: inline In-Reply-To: <1190152700.8353.14.camel-cxY/u30q8FloTgUnLF1by8fTvwmfpRNyZeezCHUQhQ4@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org * Zachary Amsden [2007-09-18 16:59]: > On Tue, 2007-09-18 at 16:25 -0500, Ryan Harper wrote: > > * Nakajima, Jun [2007-09-18 16:22]: > > > Anthony Liguori wrote: > > > > Ryan Harper wrote: > > > > > Playing around with running VMware-server within a KVM guest and > > > noticed > > > > > that whenever we launch a VM within the guest, KVM reports a GP > > > fault in > > > > > set_cr3. Removing the fault injection (raised for attempting to set > > > > > reserved bits) for the non-pae case allows memtest to boot and run > > > > > within VMWare Server, running in a KVM Linux guest. > > > > > > > > > > This same test (Linux, VMware-server, booting/running memtest iso) > > > works > > > > > fine on bare-metal. Thoughts? > > > > > > > > > > > > > Setting reserved bits is different from setting MBZ bits since the > > > > behaviors undefined. If something as common as VMware is depending on > > > > being able to set a reserved bit then perhaps the right thing to do > > > from > > > > KVM's perspective is to let it. > > > > > > > > I'm curious if Zach or Jun have any comments about the right thing to > > > do > > > > here. > > > > > > > > > > As long as the guest is protected mode (unlike the long mode), the Intel > > > spec does _not_ say that reserved bits checking is enforced for CR3. As > > > far as I looked at the AMD spec, looks like #GP is caused even in > > > protected mode... Does the test work for AMD systems? > > > > I ran my test on an AMD host. > > We have a test which verifies #GP is not caused by setting the bits on > either AMD or Intel chips. "Stray" bits can get turned on in some cases > when switching between 64-bit, PAE and non-PAE address modes. > > Were you testing on a 64-bit host kernel? 64-bit Host running 32-bit KVM Guest. VMware-server shouldn't be seeing anything 64-bit AFAIK. > > Zach -- Ryan Harper Software Engineer; Linux Technology Center IBM Corp., Austin, Tx (512) 838-9253 T/L: 678-9253 ryanh-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/