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_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 D6631C0650E for ; Fri, 5 Jul 2019 02:52:32 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (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 16F8C2184C for ; Fri, 5 Jul 2019 02:52:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 16F8C2184C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 45fzsV18GZzDqdZ for ; Fri, 5 Jul 2019 12:52:30 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=linux.ibm.com (client-ip=148.163.158.5; helo=mx0a-001b2d01.pphosted.com; envelope-from=arbab@linux.ibm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.ibm.com Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 45fzqf0GBkzDqcq for ; Fri, 5 Jul 2019 12:50:53 +1000 (AEST) Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x652lAEZ022873 for ; Thu, 4 Jul 2019 22:50:49 -0400 Received: from e11.ny.us.ibm.com (e11.ny.us.ibm.com [129.33.205.201]) by mx0a-001b2d01.pphosted.com with ESMTP id 2thr79repr-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 04 Jul 2019 22:50:49 -0400 Received: from localhost by e11.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 5 Jul 2019 03:50:46 +0100 Received: from b01ledav004.gho.pok.ibm.com (b01ledav004.gho.pok.ibm.com [9.57.199.109]) by b01cxnp22036.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x652oj5915336360 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 5 Jul 2019 02:50:45 GMT Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5DBC5112062; Fri, 5 Jul 2019 02:50:45 +0000 (GMT) Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3DBF9112061; Fri, 5 Jul 2019 02:50:45 +0000 (GMT) Received: from arbab-vm.localdomain (unknown [9.85.182.131]) by b01ledav004.gho.pok.ibm.com (Postfix) with ESMTP; Fri, 5 Jul 2019 02:50:45 +0000 (GMT) Received: from arbab-vm (localhost [IPv6:::1]) by arbab-vm.localdomain (Postfix) with ESMTP id 08944100235; Thu, 4 Jul 2019 21:50:42 -0500 (CDT) Date: Thu, 4 Jul 2019 21:50:42 -0500 From: Reza Arbab To: Nicholas Piggin Subject: Re: [v2 09/12] powerpc/mce: Enable MCE notifiers in external modules References: <20190702051932.511-1-santosh@fossix.org> <20190702051932.511-10-santosh@fossix.org> <1562047959.5y756f60wn.astroid@bobo.none> <20190703172008.aiyofnhqgbzi6ckw@arbab-vm> <1562207031.05iwu5t2xm.astroid@bobo.none> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <1562207031.05iwu5t2xm.astroid@bobo.none> Organization: IBM Linux Technology Center User-Agent: NeoMutt/20180716 X-TM-AS-GCONF: 00 x-cbid: 19070502-2213-0000-0000-000003A993D7 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00011381; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000286; SDB=6.01227588; UDB=6.00646368; IPR=6.01008826; MB=3.00027593; MTD=3.00000008; XFM=3.00000015; UTC=2019-07-05 02:50:48 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19070502-2214-0000-0000-00005F1CCF68 Message-Id: <20190705025042.nnov5s45jc4jd5ld@arbab-vm> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-07-04_10:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=835 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1907050036 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Santosh Sivaraj , "Aneesh Kumar K.V" , Mahesh Salgaonkar , Chandan Rajendra , linuxppc-dev Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, Jul 04, 2019 at 12:36:18PM +1000, Nicholas Piggin wrote: >Reza Arbab's on July 4, 2019 3:20 am: >> Since the notifier chain is actually part of the decision between (1) >> and (2), it's a hard limitation then that callbacks be in real address >> space. Is there any way to structure things so that's not the case? > >If we tested for KVM guest first, and went through and marked (maybe >in a paca flag) everywhere else that put the MMU into a bad / non-host >state, and had the notifiers use the machine check stack, then it >would be possible to enable MMU here. > >Hmm, testing for IR|DR after testing for KVM guest might actually be >enough without requiring changes outside the machine check handler... >Actually no that may not quite work because the handler could take a >SLB miss and it might have been triggered inside the SLB miss handler. > >All in all I'm pretty against turning on MMU in the MCE handler >anywhere. Hey, fair enough. Just making sure there really isnt't any room to make things work the way I was trying. >> Luckily this patch isn't really necessary for memcpy_mcsafe(), but we >> have a couple of other potential users of the notifier from external >> modules (so their callbacks would require virtual mode). > >What users are there? Do they do any significant amount of logic that >can not be moved to vmlinux? One I had in mind was the NVIDIA driver. When taking a UE from defective GPU memory, it could use the notifier to save the bad address to a blacklist in their nvram. Not so much recovering the machine check, just logging before the system reboots. The other user is a prototype driver for the IBM Research project we had a talk about offline a while back. We can make this patchset work for memcpy_mcsafe(), but I think it's back to the drawing board for the others. -- Reza Arbab