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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id AE2FBEEB580 for ; Sat, 9 Sep 2023 14:59:05 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qezPQ-0001Hx-Bo; Sat, 09 Sep 2023 10:58:04 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qezPO-0001Hn-OB for qemu-devel@nongnu.org; Sat, 09 Sep 2023 10:58:02 -0400 Received: from mx0b-00069f02.pphosted.com ([205.220.177.32]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qezPK-0001AN-Ex for qemu-devel@nongnu.org; Sat, 09 Sep 2023 10:58:02 -0400 Received: from pps.filterd (m0246630.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 389DWU5e001139; Sat, 9 Sep 2023 14:57:55 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=message-id : date : subject : to : cc : references : from : in-reply-to : content-type : content-transfer-encoding : mime-version; s=corp-2023-03-30; bh=GhN3VtMh0MCH4eH3BzF0fzbMTbij8bvRdt932bd4DC8=; b=c1sC/NXYHuq4JmkRAf6yi0HTYthMSJtCVZBsA3RcGsNVRQ76WcIDJnnJKKzU2aOqHCKp Otr6mwzEI6C7hJVD46EynlGXqOejNFHSryPTARXJusijunifnqXPuP29qYqg4HHHVA6e zgWkuOVks/LvK1dxm5LVJI3WbccV6DH1V4rzyidv38oHF3drUoWUJhOLeMxhEH3gxlfu yX3SPy7a/hY6C/54vpgnWBYAQJkGfTFTaA/mVfvot1SELDDOQZ++can1PLQEFdoQgOte bDXNMSc8W7GYMvpaEKbIVz4CfDIAiv/WfO/M4BPWdaou8R042FS90Q/t+3meVqPpSBJA 3A== Received: from iadpaimrmta01.imrmtpd1.prodappiadaev1.oraclevcn.com (iadpaimrmta01.appoci.oracle.com [130.35.100.223]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 3t0sjg01ug-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 09 Sep 2023 14:57:55 +0000 Received: from pps.filterd (iadpaimrmta01.imrmtpd1.prodappiadaev1.oraclevcn.com [127.0.0.1]) by iadpaimrmta01.imrmtpd1.prodappiadaev1.oraclevcn.com (8.17.1.19/8.17.1.19) with ESMTP id 389E0qsM002265; Sat, 9 Sep 2023 14:57:54 GMT Received: from nam11-co1-obe.outbound.protection.outlook.com (mail-co1nam11lp2170.outbound.protection.outlook.com [104.47.56.170]) by iadpaimrmta01.imrmtpd1.prodappiadaev1.oraclevcn.com (PPS) with ESMTPS id 3t0f58w8c8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 09 Sep 2023 14:57:54 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=X7KxHSeaX12uUq1zeGYTqQrjK17c2ZC0VH9kHgudaJSKeqEWDboKSkm1Si99Uf4F73xJ2QPGRlDTfLvUwQwIVUvnGyXhpsYsF3bC172ryTvtKRRPQqMdSo+kd20JdMPulJImQ16fZvKoMRqAqaMtidUORGyqHdb/DVY0Ek+StGlp4qZ8c1nSUwMkR4BMOmK48A4h6nFzEfXzXuQ6Y192ZmTqDqtbxmvLclPKrN7TJ3vKdQXzJSnxm6+GoOeTy7tsFLbyyzXInyY/N9UmZztUAwSD0plwFNYa5R2+X4tW7izvfCS3SEtUWSUkkSOnFtPvJEmk8DKEw+Iu1+uWbhl1pA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=GhN3VtMh0MCH4eH3BzF0fzbMTbij8bvRdt932bd4DC8=; b=VoLD6IyDjdYZm4v3fI9s3fmbWGiDIrNdQlSn48S3WOmimEi8bS2kqeBUk5x4BuDk57XHLdXTCNTqmR5ZegCsBrokIidj3rQ6QcL/2dV2ynI+NOl3z+1gC1XmOnd6XkaLgzu1iB/9uPXNOXAy/RYpIEQtKiOSaeYuYSZ42ZvaWjIyYJ69aVoQeWISK5Xk6XL6Yopid9kCT4csf0JZ9y0pWau0t/8Fw65yP3pbm89u8SxJfbGG5DfIqcrohQ80FuZ5/5Z6/QmJWDmW+d4GtRPFpnByhGtmMD2vL0VLHhN9OuUuiuEjZs75+HzXlyW30I8ZiJ/8oxgiY2Wh/9rNojDo7Q== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=oracle.com; dmarc=pass action=none header.from=oracle.com; dkim=pass header.d=oracle.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.onmicrosoft.com; s=selector2-oracle-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=GhN3VtMh0MCH4eH3BzF0fzbMTbij8bvRdt932bd4DC8=; b=aXU1ZnjOlPcK9vfU7vU5xYw5IHk7Q4LzNhKR4iLQM8kZxB0EK/70E7H4zAyccGkjJyLp0fWiWlP9KOmfxTkmZ0f+1aCJeT4Sw525BCEsdGmKP/OsSgLbP8klJAytbnb51u/ZDEwlJhRnM7vLF3d4GSzT/YdQqoQU4cO3IBM3pTM= Received: from BLAPR10MB4835.namprd10.prod.outlook.com (2603:10b6:208:331::11) by DS0PR10MB7066.namprd10.prod.outlook.com (2603:10b6:8:140::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6745.34; Sat, 9 Sep 2023 14:57:52 +0000 Received: from BLAPR10MB4835.namprd10.prod.outlook.com ([fe80::2867:4d71:252b:7a67]) by BLAPR10MB4835.namprd10.prod.outlook.com ([fe80::2867:4d71:252b:7a67%7]) with mapi id 15.20.6768.029; Sat, 9 Sep 2023 14:57:51 +0000 Message-ID: <40a7a752-7bdd-968d-ec5a-2a58f72a6d32@oracle.com> Date: Sat, 9 Sep 2023 15:57:44 +0100 Subject: Re: [PATCH 1/1] migration: skip poisoned memory pages on "ram saving" phase Content-Language: en-US To: William Roche , Peter Xu Cc: Paolo Bonzini , Juan Quintela , Leonardo Bras , qemu-devel@nongnu.org References: <20230906135951.795581-1-william.roche@oracle.com> <20230906135951.795581-2-william.roche@oracle.com> <3968a8e5-4010-0c97-7e1b-0dcba64ade01@oracle.com> From: Joao Martins In-Reply-To: <3968a8e5-4010-0c97-7e1b-0dcba64ade01@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-ClientProxiedBy: PA7P264CA0015.FRAP264.PROD.OUTLOOK.COM (2603:10a6:102:2d3::19) To BLAPR10MB4835.namprd10.prod.outlook.com (2603:10b6:208:331::11) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BLAPR10MB4835:EE_|DS0PR10MB7066:EE_ X-MS-Office365-Filtering-Correlation-Id: a10bc056-c759-4764-785f-08dbb14523a1 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255; CTRY:; LANG:en; SCL:1; SRV:; IPV:NLI; SFV:NSPM; H:BLAPR10MB4835.namprd10.prod.outlook.com; PTR:; CAT:NONE; SFS:(13230031)(376002)(39860400002)(396003)(366004)(136003)(346002)(1800799009)(186009)(451199024)(31686004)(36756003)(86362001)(31696002)(66899024)(478600001)(38100700002)(2616005)(26005)(5660300002)(83380400001)(2906002)(6512007)(41300700001)(6666004)(6486002)(53546011)(6506007)(66556008)(66476007)(66946007)(54906003)(4326008)(8676002)(110136005)(8936002)(316002)(45980500001); DIR:OUT; SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?aHRtRkFQT0xkVUhPV0NyRG1kV2ZnWGZnU0JqdDV6emtod3VDbUo0NXloQjg5?= =?utf-8?B?TmZKcGF1SUNKMURMSnBXN2MxNW0zc0FCblh1b05MbXJaNDZJNXU1YjZCcEdl?= =?utf-8?B?bnhLUVpsWXh3TnRtZGFxeDhWQXhNNExDQ3RhQWNmaDFNbEQrUU16WG5YRXo2?= =?utf-8?B?K1REVWtsYll0eFpmS2RYa1VvYzVveWlWd0tQWDhpSFVKUnB5OC9NM2V6Vkda?= =?utf-8?B?YXo3VkphWi81ODliUUliUWZOSmtiRjJtZ2RGOXNwQ1FSaG5vdjJQc0t6Ky81?= =?utf-8?B?Q1h0UTJ1d0VqWnVZL2FFR1FheVNRc0wxV0g5bmtXZW9QWXIrR0x5aEh1eEhj?= =?utf-8?B?MTYzTHZzUFVSSTgrdnR1bEhHbWZYUmU4TWNZdnBpVWNyZjRMVmpFME5FSWF0?= =?utf-8?B?Y2dYckNYd3ZtRnRuSFE0c1Z1SEVPKzlIOWJuSURkcnNyUlV4c2NDMHkvakNk?= =?utf-8?B?SkE5eHp1RXh0SVRtVVlxYlpQbzVHd3BqbzhVVmo5bTMzUktwdDZUbXJrblNj?= =?utf-8?B?STFpWC9wdk5DdWo1UHNMeEFaM2RCNGtjeVVqMG1MVFFjWFdWUHJiVFJ6bjJu?= =?utf-8?B?N0NzRXdWZldRbWNYTHhRTndBdmllMHgyTHQ0d2p6VHNsOElZNTVtK0pneGJL?= =?utf-8?B?NDgwMXRiS2l2NTkvUkJIZEM1ODhmTmFJUnBzQnBtRVROalJTNnhyUjhlZVJ6?= =?utf-8?B?VHV1TWNPS0piQ0hiaGU5ZFNVbVV5ZTRSWmhxenRnV0VyNVk3WDI3TmRRUjVE?= =?utf-8?B?MWoxS2xyVVdGOE1ySXpYbk5KeXowdjFjNHdKZHNoc2dyQ0Z6cllLbXQzUW5k?= =?utf-8?B?L3dVSEtMT3piVUpNNnZUbXJSQmx1MWZqK1JCMHQ3ak1DeWZyd05tZUI5R3J2?= =?utf-8?B?Zlp1U3U5MStLUXlzS3kxUmEzSXlvQ1R6a2JiMkh3WDdzenFkd3YxL29GL1VO?= =?utf-8?B?VndpV1VEdDA3ZzdXRmlKSWNRcUE4WFVDLzNQaVhRV21EM0w5Ti9Ka016RnR1?= =?utf-8?B?dGdXRUlMQmJPVGc2eDVmQlBxLzcvZGR4MzBzb1U5WXNSM1g5dU9MOVY5VWFa?= =?utf-8?B?dGU2S2c5VjRGUXpyblZ4TXhpT3RwV1NnL2xsR3BrL1ZidFkxOG04WEozMUt6?= =?utf-8?B?WmNERWQ2MGtxSUVnd1Bvb09pclVjYkNpUG1WR1dySERjUEJ6MmVBbDZJMjBH?= =?utf-8?B?MTh3eUcxYnNiVzdlSExQYjhVTTZFUzFpL096cnZuSVIycGF2Tlk1Tm5QOGlL?= =?utf-8?B?TmRqSmZ2dEVSdkM4T2ZicWxwOSt3MzZiRUFwV0V1UlI1NzdxVk1HY0g3Mnp4?= =?utf-8?B?S1I4TkpNd2c0Q2NNWG9saTY2S0dpeCtTQ3VJZ2gvUFNPenRIVnJ3NE5oQS9X?= =?utf-8?B?dC9ZQ2gvSUhJVnJZaVJNMlhCK2FUSzVvUTlHMjA0QThsVnZhUThBdTVqSmhJ?= =?utf-8?B?OWQyZEsrLzVueXNteXZrUEhmWWxhMkxIK1k1MUdvSDBiMkVyUVFub1R2aUpG?= =?utf-8?B?R21BbEpTdkdhbExLNEZzVURKVkdMcXJmT1FVWlJyOHQ4K1QvQi9OOGlVR21O?= =?utf-8?B?ajZOTXdqZk5XVUxvMlVuK1U3RWhUbU5OZndqZGhoL2VFeTZGRE90eVk4OXZW?= =?utf-8?B?cURpc1dKU29jbEpTdmVRMy9GOWFWbmt3dXA5dStvZGRiWjB1QjNjd2tMSWpZ?= =?utf-8?B?VWtCQlhRUHAwZXM2VDRMc09WM2FzejhOSkdXZzcrSGE5NkZucFFoc2J0K0Zl?= =?utf-8?B?dzhhblNLdnJDdUhDZlRwVWV1eDRVajEwbmhOTnFnU3l2ZTRFVzZQNWNydEo1?= =?utf-8?B?S2ZnNXpNZURxOWp2Ni9BeWtJNEJRU2xhQ2wzRnNuMWdVM08wWGI1dkJSUXFz?= =?utf-8?B?M1IvaUpiWjZpczVjc25tbzFoNThhQ21XZmJKeGFYSVBWWHp6NHJWL1RhY0Vl?= =?utf-8?B?Zi9XekVIV05RbjZzQkRvSFhGQll3b0xkbHlsSWtPZlcrZ2ZoL0tnUzJBVGZM?= =?utf-8?B?eTJzT0c4cVVDLzFqdmZDNmo1M2JqMFRNQW91QzcyakQrTkltNTdxbEtDL1Qx?= =?utf-8?B?V3EwcVlCNTB5czVyOWlqZ3R0K3pQTzVNZHdYZklJc05HRkRIUTJZUzdpWXFN?= =?utf-8?B?VlMwS3IvaCthak1DQldLOGd0M01EaFIySVF6dTN5RS9qWm1lVFNsRWliOFpG?= =?utf-8?B?bWc9PQ==?= X-MS-Exchange-AntiSpam-ExternalHop-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-ExternalHop-MessageData-0: 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 X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-Network-Message-Id: a10bc056-c759-4764-785f-08dbb14523a1 X-MS-Exchange-CrossTenant-AuthSource: BLAPR10MB4835.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Sep 2023 14:57:51.3593 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: WuE0tyNbM6X24zVr5GELSpsLHjJCp0ynucdb5wgZIu+1AIi4yiVS9cG4whcDxqz/j4AtTHks0OPBEotrrxBy+UgINDmvzAiN/ctbv59Uc2U= X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR10MB7066 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.267,Aquarius:18.0.957,Hydra:6.0.601,FMLib:17.11.176.26 definitions=2023-09-09_13,2023-09-05_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 mlxscore=0 bulkscore=0 adultscore=0 phishscore=0 spamscore=0 mlxlogscore=999 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2308100000 definitions=main-2309090135 X-Proofpoint-ORIG-GUID: T_kE36D2UV4NfU0Gpzql2OSpg-hhMKn9 X-Proofpoint-GUID: T_kE36D2UV4NfU0Gpzql2OSpg-hhMKn9 Received-SPF: pass client-ip=205.220.177.32; envelope-from=joao.m.martins@oracle.com; helo=mx0b-00069f02.pphosted.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 06/09/2023 22:29, William Roche wrote: > On 9/6/23 17:16, Peter Xu wrote: >> >> Just a note.. >> >> Probably fine for now to reuse block page size, but IIUC the right thing to >> do is to fetch it from the signal info (in QEMU's sigbus_handler()) of >> kernel_siginfo.si_addr_lsb. >> >> At least for x86 I think that stores the "shift" of covered poisoned page >> (one needs to track the Linux handling of VM_FAULT_HWPOISON_LARGE for a >> huge page, though.. not aware of any man page for that).  It'll then work >> naturally when Linux huge pages will start to support sub-huge-page-size >> poisoning someday.  We can definitely leave that for later. >> > > I totally agree with that ! > Provided this bug affects all qemu versions thus far, perhaps should be a follow up series, to make the changer easier to bring into stable tree. > >>>> --- a/migration/ram.c >>>> +++ b/migration/ram.c >>>> @@ -1145,7 +1145,8 @@ static int save_zero_page_to_file(PageSearchStatus >>>> *pss, QEMUFile *file, >>>>       uint8_t *p = block->host + offset; >>>>       int len = 0; >>>>   -    if (buffer_is_zero(p, TARGET_PAGE_SIZE)) { >>>> +    if ((kvm_enabled() && kvm_hwpoisoned_page(block, (void *)offset)) || >> >> Can we move this out of zero page handling?  Zero detection is not >> guaranteed to always be the 1st thing to do when processing a guest page. >> Currently it'll already skip either rdma or when compression enabled, so >> it'll keep crashing there. >> >> Perhaps at the entry of ram_save_target_page_legacy()? > > Right, as expected, using migration compression with poisoned pages crashes even > with this fix... > > The difficulty I see to place the poisoned page verification on the > entry of ram_save_target_page_legacy() is what to do to skip the found poison > page(s) if any ? > > Should I continue to treat them as zero pages written with > save_zero_page_to_file ? MCE had already been forward to the guest, so guest is supposed to not be using the page (nor rely on its contents). Hence destination ought to just see a zero page. So what you said seems like the best course of action. > Or should I consider the case of an ongoing compression > use and create a new code compressing an empty page with save_compress_page() ? > The compress code looks to be a tentative compression (not guaranteed IIUC), so I am not sure it needs any more logic that just adding at the top of ram_save_target_page_legacy() as Peter suggested? > And what about an RDMA memory region impacted by a memory error ? > This is an important aspect. > Does anyone know how this situation is dealt with ? And how it should be handled > in Qemu ? > If you refer to guest RDMA MRs that is just guest RAM, not sure we are even aware of those from qemu. But if you refer to the RDMA transport that sits below the Qemu file (or rather acts as an implementation of QemuFile), so handling in ram_save_target_page_legacy() already seems to cover it. > -- > Thanks, > William.