From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [RFC][PATCH] ignore set_cr3 GP fault in non-pae mode Date: Wed, 19 Sep 2007 10:08:15 -0500 Message-ID: <46F13B5F.4050107@codemonkey.ws> 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> <20070918220308.GF7519@us.ibm.com> <46F0E46C.1060905@qumranet.com> <20070919145536.GH7519@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Zachary Amsden , kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, Avi Kivity To: Ryan Harper Return-path: In-Reply-To: <20070919145536.GH7519-r/Jw6+rmf7HQT0dZR+AlfA@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 Ryan Harper wrote: > * Avi Kivity [2007-09-19 03:58]: > >> Ryan Harper wrote: >> >>>> 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. >>> >>> >> If the host is 64-bit, so is the guest, although the guest can choose to >> ignore the 64-bit capabilities (and 32-bit guest OSes do; but VMware >> might be doing something tricky). >> > > Hrm. I'm not sure I understand the distiction you are making. I'll > give a 32-bit host a try without the patch and see if I see the same > behavior. > On a 64-bit host, even if the guest kernel is 32-bit the guest could still detect the ability to run in 64-bit mode. The thinking is that VMware may be detecting 64-bit capabilities and doing something weird. I think that's somewhat orthogonal to this patch. It seems like ignoring setting of reserved bits is the right thing to do in 32-bit mode. Does anyone disagree with that? Regards, Anthony Liguori ------------------------------------------------------------------------- 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/