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=-2.5 required=3.0 tests=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 47052C10F14 for ; Tue, 23 Apr 2019 10:49:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1B4992177B for ; Tue, 23 Apr 2019 10:49:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727616AbfDWKtc (ORCPT ); Tue, 23 Apr 2019 06:49:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36822 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727458AbfDWKtc (ORCPT ); Tue, 23 Apr 2019 06:49:32 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 340FD81F0F; Tue, 23 Apr 2019 10:49:32 +0000 (UTC) Received: from dhcp-128-65.nay.redhat.com (ovpn-12-71.pek2.redhat.com [10.72.12.71]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7591B60142; Tue, 23 Apr 2019 10:49:28 +0000 (UTC) Date: Tue, 23 Apr 2019 18:49:24 +0800 From: Dave Young To: Junichi Nomura Cc: Kairui Song , "linux-kernel@vger.kernel.org" , Borislav Petkov , Thomas Gleixner , Chao Fan , Baoquan He , "x86@kernel.org" , "kexec@lists.infradead.org" Subject: Re: [PATCH] x86/kexec: always ensure EFI systab region is mapped Message-ID: <20190423104924.GA1730@dhcp-128-65.nay.redhat.com> References: <20190422092804.15534-1-kasong@redhat.com> <965f770a-b103-72fb-eaef-cb337ebe8290@ce.jp.nec.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <965f770a-b103-72fb-eaef-cb337ebe8290@ce.jp.nec.com> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Tue, 23 Apr 2019 10:49:32 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/23/19 at 06:20am, Junichi Nomura wrote: > 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? Hmm, guess it should be mapped by luck, here is the range on the T420: da99f000 - dae9efff Reserved (efi systab fall in this region) daf9f000 - daffefff ACPI tables Thanks Dave