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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,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 314A7C072B5 for ; Wed, 22 May 2019 03:24:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 05BED217D9 for ; Wed, 22 May 2019 03:24:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728405AbfEVDYJ (ORCPT ); Tue, 21 May 2019 23:24:09 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47284 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727733AbfEVDYJ (ORCPT ); Tue, 21 May 2019 23:24:09 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 7B04933025F; Wed, 22 May 2019 03:24:09 +0000 (UTC) Received: from dhcp-128-65.nay.redhat.com (ovpn-12-78.pek2.redhat.com [10.72.12.78]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5581D646BB; Wed, 22 May 2019 03:24:06 +0000 (UTC) Date: Wed, 22 May 2019 11:24:02 +0800 From: Dave Young To: Baoquan He Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@kernel.org, bp@alien8.de, hpa@zytor.com, kirill.shutemov@linux.intel.com, x86@kernel.org Subject: Re: [PATCH v4 2/3] x86/kexec/64: Error out if try to jump to old 4-level kernel from 5-level kernel Message-ID: <20190522032402.GA31575@dhcp-128-65.nay.redhat.com> References: <20190509013644.1246-1-bhe@redhat.com> <20190509013644.1246-3-bhe@redhat.com> <20190522032029.GB31269@dhcp-128-65.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190522032029.GB31269@dhcp-128-65.nay.redhat.com> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Wed, 22 May 2019 03:24:09 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/22/19 at 11:20am, Dave Young wrote: > On 05/09/19 at 09:36am, Baoquan He wrote: > > If the running kernel has 5-level paging activated, the 5-level paging > > mode is preserved across kexec. If the kexec'ed kernel does not contain > > support for handling active 5-level paging mode in the decompressor, the > > decompressor will crash with #GP. > > > > Prevent this situation at load time. If 5-level paging is active, check the > > xloadflags whether the kexec kernel can handle 5-level paging at least in > > the decompressor. If not, reject the load attempt and print out error > > message. > > > > Signed-off-by: Baoquan He > > Acked-by: Kirill A. Shutemov > > --- > > arch/x86/kernel/kexec-bzimage64.c | 5 +++++ > > How about the userspace kexec-tools? It needs a similar detection, but > I'm not sure how to detect paging mode, maybe some sysfs entry or > vmcoreinfo in /proc/vmcore meant /proc/kcore ... Thanks Dave