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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 4171DC10F14 for ; Tue, 23 Apr 2019 06:21:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0BC3E214AE for ; Tue, 23 Apr 2019 06:21:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726154AbfDWGVP convert rfc822-to-8bit (ORCPT ); Tue, 23 Apr 2019 02:21:15 -0400 Received: from tyo162.gate.nec.co.jp ([114.179.232.162]:41186 "EHLO tyo162.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725882AbfDWGVP (ORCPT ); Tue, 23 Apr 2019 02:21:15 -0400 Received: from mailgate02.nec.co.jp ([114.179.233.122]) by tyo162.gate.nec.co.jp (8.15.1/8.15.1) with ESMTPS id x3N6KdCK014629 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Tue, 23 Apr 2019 15:20:39 +0900 Received: from mailsv01.nec.co.jp (mailgate-v.nec.co.jp [10.204.236.94]) by mailgate02.nec.co.jp (8.15.1/8.15.1) with ESMTP id x3N6KdqH016893; Tue, 23 Apr 2019 15:20:39 +0900 Received: from mail01b.kamome.nec.co.jp (mail01b.kamome.nec.co.jp [10.25.43.2]) by mailsv01.nec.co.jp (8.15.1/8.15.1) with ESMTP id x3N6ESia028768; Tue, 23 Apr 2019 15:20:39 +0900 Received: from bpxc99gp.gisp.nec.co.jp ([10.38.151.139] [10.38.151.139]) by mail02.kamome.nec.co.jp with ESMTP id BT-MMP-4548273; Tue, 23 Apr 2019 15:20:10 +0900 Received: from BPXM12GP.gisp.nec.co.jp ([10.38.151.204]) by BPXC11GP.gisp.nec.co.jp ([10.38.151.139]) with mapi id 14.03.0319.002; Tue, 23 Apr 2019 15:20:10 +0900 From: Junichi Nomura To: Kairui Song , "linux-kernel@vger.kernel.org" CC: Borislav Petkov , Thomas Gleixner , "Chao Fan" , Baoquan He , Dave Young , "x86@kernel.org" , "kexec@lists.infradead.org" Subject: Re: [PATCH] x86/kexec: always ensure EFI systab region is mapped Thread-Topic: [PATCH] x86/kexec: always ensure EFI systab region is mapped Thread-Index: AQHU+O3agAmzlxHZg0mE9lemKT/NC6ZIsHeA Date: Tue, 23 Apr 2019 06:20:09 +0000 Message-ID: <965f770a-b103-72fb-eaef-cb337ebe8290@ce.jp.nec.com> References: <20190422092804.15534-1-kasong@redhat.com> In-Reply-To: <20190422092804.15534-1-kasong@redhat.com> Accept-Language: en-US, ja-JP Content-Language: ja-JP X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.34.125.85] Content-Type: text/plain; charset="iso-2022-jp" Content-ID: <92F1F186A0F7274C960CCFCB661342A2@gisp.nec.co.jp> Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-TM-AS-MML: disable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/22/19 6:28 PM, Kairui Song wrote: > The reason is the systab region is not mapped by the identity mapping > provided by kexec. Currently kexec only create identity mapping for > mem regions, wihch won't cover the systab. So second kernel will be > accessing a not mapped memory region and cause fault. > But as kexec tend to pad the map region up to PUD size, the > systab could be included in the map by accident, so it worked on > some machines, but that will be broken easily and unstable. Is the mapping of ACPI tables just by luck, too? -- Jun'ichi Nomura, NEC Corporation / NEC Solution Innovators, Ltd.