From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932237Ab2IVAlr (ORCPT ); Fri, 21 Sep 2012 20:41:47 -0400 Received: from out02.mta.xmission.com ([166.70.13.232]:56012 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754747Ab2IVAlq (ORCPT ); Fri, 21 Sep 2012 20:41:46 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: "H. Peter Anvin" Cc: Linux Kernel Mailing List , "H. Peter Anvin" , Ingo Molnar , Thomas Gleixner , Linus Torvalds , Kees Cook , Linda Wang , Matt Fleming References: <1348256595-29119-1-git-send-email-hpa@linux.intel.com> <877grnows4.fsf@xmission.com> <505CE638.1030405@linux.intel.com> Date: Fri, 21 Sep 2012 17:41:34 -0700 In-Reply-To: <505CE638.1030405@linux.intel.com> (H. Peter Anvin's message of "Fri, 21 Sep 2012 15:12:08 -0700") Message-ID: <87sjaaj3cx.fsf@xmission.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=;;;mid=;;;hst=in01.mta.xmission.com;;;ip=98.207.153.68;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1+4YdxiIX21sal+zSocpMPelgR7EhQVvLs= X-SA-Exim-Connect-IP: 98.207.153.68 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 1.5 XMNoVowels Alpha-numberic number with no vowels * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -3.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa01 1397; Body=1 Fuz1=1 Fuz2=1] X-Spam-DCC: XMission; sa01 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;"H. Peter Anvin" X-Spam-Relay-Country: Subject: Re: [PATCH 00/11] x86: Supervisor Mode Access Prevention X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Fri, 06 Aug 2010 16:31:04 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org "H. Peter Anvin" writes: > On 09/21/2012 03:07 PM, Eric W. Biederman wrote: >> >> Have you tested kexec in this environment? >> >> This is the kind of cpu feature that when we enable it, frequently we >> have to do something on the kexec path. >> >> At a quick skim it looks like the kexec path is using kernel page table >> entries and clearing all bits from cr4 except X86_CR4_PAE so I don't >> actually expect this change will require anything on the kexec path. >> > > I have not, no, but as you quite correctly point out that shouldn't > affect things. > > We should also change the kernel to start clean with CR4 -- the purpose > of CR4 is to indicate which CPU features the OS is opting into. > > I think we do on x86-64 but not on x86-32 at the moment. > > This is an unrelated problem, though, and can be addressed later. Agreed. I just was just curious where things stood. Eric