From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.skyhub.de ([2a01:4f8:190:11c2::b:1457]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1hEwLF-0006LJ-Rz for kexec@lists.infradead.org; Fri, 12 Apr 2019 13:35:45 +0000 Date: Fri, 12 Apr 2019 15:35:29 +0200 From: Borislav Petkov Subject: Re: [PATCH v4] x86/boot: Use efi_setup_data for searching RSDP on kexec-ed kernel Message-ID: <20190412133528.GD19808@zn.tnic> References: <20190411080927.GA30080@zn.tnic> <20190411083738.GC30080@zn.tnic> <2946b5e3-90bf-d617-16a4-d2225b490b5d@ce.jp.nec.com> <20190411125822.GE30080@zn.tnic> <20190412025416.GA11070@jeru.linux.bs1.fc.nec.co.jp> <20190412084956.GC19808@zn.tnic> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190412084956.GC19808@zn.tnic> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Junichi Nomura Cc: Chao Fan , Kairui Song , Baoquan He , "x86@kernel.org" , "kexec@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Dave Young On Fri, Apr 12, 2019 at 10:49:56AM +0200, Borislav Petkov wrote: > Now I need to go figure out whether there's a reliable way to know in > the kexec kernel that it *is* a kexec kernel. Actually, thinking about this more, we don't need to know whether the kernel was kexeced or not. Why? Because if it is kexec'ed, kexec(1) passes the required info in setup_data. Now, if for whatever reason the kexec'ed kernel fails to parse that EFI info and get the systab to figure out the RDSP, then it doesn't have any other choice but fail booting. Because there's no way it can figure out where the EFI runtime has been mapped and recover by finding the RDSP from there. So I think we're perfectly fine with the old approach: if (!pa) pa = kexec_get_rsdp_addr(); if (!pa) pa = efi_get_rsdp_addr(); -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply. _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5FE2DC10F0E for ; Fri, 12 Apr 2019 13:35:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 22C452084D for ; Fri, 12 Apr 2019 13:35:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="VLMZE5yI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726963AbfDLNfh (ORCPT ); Fri, 12 Apr 2019 09:35:37 -0400 Received: from mail.skyhub.de ([5.9.137.197]:58026 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726765AbfDLNfh (ORCPT ); Fri, 12 Apr 2019 09:35:37 -0400 Received: from zn.tnic (p200300EC2F08840068A43035F0D96009.dip0.t-ipconnect.de [IPv6:2003:ec:2f08:8400:68a4:3035:f0d9:6009]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id A22581EC00FF; Fri, 12 Apr 2019 15:35:35 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1555076135; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=UPWzm4vt0PY0+c6ptfDK1JVk5pXwzJlg2U0OHKqmWuM=; b=VLMZE5yIeNBHSYJO5gtOS9RFE0nPnE/DxnEqxK4QL1cL/n30Mmy4QjFVOW8mvYBVD3fBip I7GycxOPpw2zTqEy5Z/Q8SqTq/2fp+58tKKkXVgj866G0jmydI5qCgpFFfdU9nCz91KHRb Tuc6kkH21HBgev+lEkrptFs/h9vFRJI= Date: Fri, 12 Apr 2019 15:35:29 +0200 From: Borislav Petkov To: Junichi Nomura Cc: Dave Young , Chao Fan , Baoquan He , Kairui Song , "x86@kernel.org" , "kexec@lists.infradead.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v4] x86/boot: Use efi_setup_data for searching RSDP on kexec-ed kernel Message-ID: <20190412133528.GD19808@zn.tnic> References: <20190411080927.GA30080@zn.tnic> <20190411083738.GC30080@zn.tnic> <2946b5e3-90bf-d617-16a4-d2225b490b5d@ce.jp.nec.com> <20190411125822.GE30080@zn.tnic> <20190412025416.GA11070@jeru.linux.bs1.fc.nec.co.jp> <20190412084956.GC19808@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190412084956.GC19808@zn.tnic> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 12, 2019 at 10:49:56AM +0200, Borislav Petkov wrote: > Now I need to go figure out whether there's a reliable way to know in > the kexec kernel that it *is* a kexec kernel. Actually, thinking about this more, we don't need to know whether the kernel was kexeced or not. Why? Because if it is kexec'ed, kexec(1) passes the required info in setup_data. Now, if for whatever reason the kexec'ed kernel fails to parse that EFI info and get the systab to figure out the RDSP, then it doesn't have any other choice but fail booting. Because there's no way it can figure out where the EFI runtime has been mapped and recover by finding the RDSP from there. So I think we're perfectly fine with the old approach: if (!pa) pa = kexec_get_rsdp_addr(); if (!pa) pa = efi_get_rsdp_addr(); -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.