Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753665Ab3FFTip (ORCPT ); Thu, 6 Jun 2013 15:38:45 -0400 Received: from terminus.zytor.com ([198.137.202.10]:39674 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751552Ab3FFTio (ORCPT ); Thu, 6 Jun 2013 15:38:44 -0400 Message-ID: <51B0E522.4070005@zytor.com> Date: Thu, 06 Jun 2013 12:38:10 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130514 Thunderbird/17.0.6 MIME-Version: 1.0 To: Borislav Petkov CC: Matt Fleming , Linux EFI , Matthew Garrett , Jiri Kosina , X86-ML , LKML , Borislav Petkov Subject: Re: [PATCH 4/4] x86, efi: Map runtime services 1:1 References: <1370177770-26661-1-git-send-email-bp@alien8.de> <1370177770-26661-5-git-send-email-bp@alien8.de> <20130606131439.GI30420@console-pimps.org> <20130606132908.GE20972@pd.tnic> <20130606155822.GH20972@pd.tnic> <51B0E2D4.3040007@zytor.com> <20130606193612.GM20972@pd.tnic> In-Reply-To: <20130606193612.GM20972@pd.tnic> X-Enigmail-Version: 1.5.1 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1092 Lines: 26 On 06/06/2013 12:36 PM, Borislav Petkov wrote: > On Thu, Jun 06, 2013 at 12:28:20PM -0700, H. Peter Anvin wrote: >> Or we could materialize mappings for this specific PGD. However, >> adding a read of %cr3 in __do_page_fault sounds expensive. > > Yes, I think we want to make sure all mappings are there when we do an > EFI runtime call so that we never #PF while it executes. > > Matt mentioned on IRC that the it could be that his EFI runtime is > referencing EFI_RESERVED area which we don't map. However, we need to > confirm/disprove that first, as it is currently only a hunch. If it is true, then maybe a #PF handler which materializes mappings on demand might be the right thing to do. Again, it would be interesting to stop a WinX VM in the process of doing an EFI call and see exactly what it has set up in its page tables. -hpa -- 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/