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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 9714BC2D0E4 for ; Mon, 23 Nov 2020 08:23:19 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E05AB20719 for ; Mon, 23 Nov 2020 08:23:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="PiVBmoy4" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E05AB20719 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:46556 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kh781-0005U8-Tg for qemu-devel@archiver.kernel.org; Mon, 23 Nov 2020 03:23:17 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:37516) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kh6xS-0001Cg-30 for qemu-devel@nongnu.org; Mon, 23 Nov 2020 03:12:23 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:47596) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kh6xQ-0007xs-JK for qemu-devel@nongnu.org; Mon, 23 Nov 2020 03:12:21 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606119139; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=N9aXAV4ugHm3jPLNYZMcT2DUbKXs9ePfP19cI1qQjSY=; b=PiVBmoy4eEeUrUn+SbD62M+F6qBZYHaFb+WDJyR/tJ9N6556mgZJFpGNnDGgVUHLwoOZR1 w2y4B1pGH4RMTLW24Lasvc9JBXUY9DyTvgXknI+photJ+Bg82PG5uGGwJuZJI+bj49e6wc XoSRe0SWnJh5JTqhzaS37cAOyoXtxvc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-256-_QBO8e7dP8uq6lKqmgpDQg-1; Mon, 23 Nov 2020 03:12:15 -0500 X-MC-Unique: _QBO8e7dP8uq6lKqmgpDQg-1 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id 2B469108E1AC; Mon, 23 Nov 2020 08:12:05 +0000 (UTC) Received: from thuth.remote.csb (ovpn-113-17.ams2.redhat.com [10.36.113.17]) by smtp.corp.redhat.com (Postfix) with ESMTP id 46BE960864; Mon, 23 Nov 2020 08:12:03 +0000 (UTC) Subject: Re: [PATCH v2 2/2] pc-bios: s390x: Clear out leftover S390EP string To: Christian Borntraeger , Eric Farman , Cornelia Huck References: <20201120160117.59366-1-farman@linux.ibm.com> <20201120160117.59366-3-farman@linux.ibm.com> <4738082f-ec10-e2a3-7756-9180a57329bb@redhat.com> <1ad47eb6-5aca-a766-3bad-aa38924b5ef8@de.ibm.com> From: Thomas Huth Message-ID: Date: Mon, 23 Nov 2020 09:12:02 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <1ad47eb6-5aca-a766-3bad-aa38924b5ef8@de.ibm.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=thuth@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=thuth@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jason Herne , qemu-s390x@nongnu.org, Janosch Frank , Matthew Rosato , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 23/11/2020 09.07, Christian Borntraeger wrote: > > > On 23.11.20 09:05, Thomas Huth wrote: >> On 23/11/2020 08.39, Christian Borntraeger wrote: >>> On 20.11.20 17:01, Eric Farman wrote: >>>> A Linux binary will have the string "S390EP" at address 0x10008, >>>> which is important in getting the guest up off the ground. In the >>>> case of a reboot (specifically chreipl going to a new device), >>>> we should defer to the PSW at address zero for the new config, >>>> which will re-write "S390EP" from the new image. >>>> >>>> Let's clear it out at this point so that a reipl to, say, a DASD >>>> passthrough device drives the IPL path from scratch without disrupting >>>> disrupting the order of operations for other boots. >>>> >>>> Rather than hardcoding the address of this magic (again), let's >>>> define it somewhere so that the two users are visibly related. >>> >>> >>> Hmmm, this might have side effects, e.g. if you do something like a kdump >>> or kexec to a non-Linux binary that happens to have code at 0x10008, no? >> >> Do these scenarios really go through the s390-ccw bios again, or do they >> rather bypass the bios and jump directly into the new kernel? > > Right they jump directly into the new kernel. So this patch could actually > be "good enough" for 5.2 as is? I think it should be fine, yes. I'll give it a try with my usual s390-ccw bios tests, and if there are no regressions (and no other objections on the mailing list here), I'll prepare a pull request. Thomas