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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21CC2C77B7C for ; Wed, 10 May 2023 20:41:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236634AbjEJUl0 (ORCPT ); Wed, 10 May 2023 16:41:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33838 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236605AbjEJUlU (ORCPT ); Wed, 10 May 2023 16:41:20 -0400 Received: from NAM11-CO1-obe.outbound.protection.outlook.com (mail-co1nam11on2074.outbound.protection.outlook.com [40.107.220.74]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CE88872AA; Wed, 10 May 2023 13:41:13 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=IKsiHOD9pT3TtMA4taQ36Iz2WwlqJU3KmSRaj5ICVngnuCo34c/rleIariqdXQRfiRCwpBIJ4UVlS6y5GBfIeyOt0UKG1TovEV3KbJKaKhSHdRIBy3iOc3ym3IxQwdwf846GrP/GBhQuzE3ucyhCfnckogaeZcZaIXWxmyBDYbAnXUeP7MLrT9Y13BGKfghGtu09YiFfomb0U/vrb+SHra+b9DQFLoPvbRvCWN9J82TrJwvesQFi0+rf02yq8m/xCmvpJwWstrv9xNcDBArsUU0L+Px8sM9UtwKYOZvTjX6zSRDD3lfrRM+Skbti4ShE7BXsXj1DrlcXm2TLbAcyiQ== 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=2Y9Tm61cFnRT0R3ck4L5v5CpwL7iXFI7jmnXzGD1ZAo=; b=jAqYsCptyL7BKpK7BRayQNfwPtvF+G4zGBgXqe2XlEnq5AoT4omTmMPzODteYpgwqBUm9tmdJTPswJF9rkzUuJudmHZhUk6t59RTxF3V7W19TgaP6/K5W2sVeTjTC3CfOcOD6sS3yTXXRZR+mqxPPCWbGv1sktgcGS89cQeWDNv5P709bGNI+slzhAMdqnGPaogQt3kxjQ/DT/0kHpc7/HdzrhYI/oZS+SPAtGlPnKuCccFk4WK9qifhQ9v1VWbPhmG3kJdoUIVmJsLJfFVEzVEtxN9hz3ZBSUbFL0R9pLWOjprHo/waT5doKPT47vrK50LZbhtPDqGqAT/0IL7ltw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com; dkim=pass header.d=nvidia.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=2Y9Tm61cFnRT0R3ck4L5v5CpwL7iXFI7jmnXzGD1ZAo=; b=KGUO5UAZeLoL9xnB6NpEebMtdXH6nOypyXaKfp/uLiM8OrIP5WllNucc9oWKjjnruOMvMy7aTrmLHNhaQyrjDaRcutSjIQD7ewXxe5zTK3HfeDI8OBZz8opHi4t474e6rlY0m1fb5zmmEureTRy6uulec8JRJGV4WTzRwgAlH+O0FAR09W4XFuJq1chkBd2ofZ+vfSOVON0fQsakcGSYts9rZOq66XXUMCzpxkvBYdUPvtVDHZCDJFEh0qaLU+FkBxGkUAIUCrkfScgoUpi2v+Hi37Jid5UM8uL4mWjxEfE5PbiiLXtcv9nC2epiPNh+F38cSY3+v9VxguiCWi5qYA== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from LV2PR12MB5869.namprd12.prod.outlook.com (2603:10b6:408:176::16) by BY5PR12MB4966.namprd12.prod.outlook.com (2603:10b6:a03:1da::15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6387.19; Wed, 10 May 2023 20:41:09 +0000 Received: from LV2PR12MB5869.namprd12.prod.outlook.com ([fe80::f7a7:a561:87e9:5fab]) by LV2PR12MB5869.namprd12.prod.outlook.com ([fe80::f7a7:a561:87e9:5fab%6]) with mapi id 15.20.6363.032; Wed, 10 May 2023 20:41:08 +0000 Date: Wed, 10 May 2023 17:41:06 -0300 From: Jason Gunthorpe To: Alex Williamson Cc: Yan Zhao , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, kevin.tian@intel.com, yishaih@nvidia.com, shameerali.kolothum.thodi@huawei.com, =?utf-8?Q?C=C3=A9dric?= Le Goater Subject: Re: [PATCH] vfio/pci: take mmap write lock for io_remap_pfn_range Message-ID: References: <20230508125842.28193-1-yan.y.zhao@intel.com> <20230508145715.630fe3ae.alex.williamson@redhat.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230508145715.630fe3ae.alex.williamson@redhat.com> X-ClientProxiedBy: MW4PR04CA0217.namprd04.prod.outlook.com (2603:10b6:303:87::12) To LV2PR12MB5869.namprd12.prod.outlook.com (2603:10b6:408:176::16) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: LV2PR12MB5869:EE_|BY5PR12MB4966:EE_ X-MS-Office365-Filtering-Correlation-Id: f01f2d22-6c17-4fdb-720d-08db5196e24b 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:LV2PR12MB5869.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230028)(4636009)(376002)(136003)(396003)(39860400002)(346002)(366004)(451199021)(2906002)(2616005)(4744005)(6486002)(54906003)(66556008)(66946007)(316002)(66476007)(478600001)(8936002)(186003)(8676002)(6506007)(6512007)(26005)(41300700001)(5660300002)(6916009)(4326008)(38100700002)(86362001)(36756003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?ksAbYT6KcOeHHutdwWZxPJft+lr4QWa/dXba0xznp7aTdafUoseZ614+D5l4?= =?us-ascii?Q?W7JHqGNC+d96TR1+WiuSb8LJJ0GavF3lGY1MA6adIIRmHMuJ8vRRM0sj5tfd?= =?us-ascii?Q?4zzGMRjDK+cugX5W7jLAxYpGN500xoIdMnGUZ+0J+q5k5+Cj4q5Y2l49tZhf?= =?us-ascii?Q?fNlohS+rxNKgavDl0VSJyYmP025CVa6uqXw8jgtueKoThgyFi3f8/yV923A2?= =?us-ascii?Q?D78fSK36dMZ5KDU1ZSDOoraMGY+TmeVSyDoMZPc53xTXnjUxYCu5v3z/8DUK?= =?us-ascii?Q?/hM7//cDAxSJFbbxOaHUrE+g9286W7F+P71zOfPePBVi9WdWArYPGbji4oBr?= =?us-ascii?Q?OqlOF1j+cGXKeofzxFbqxYqsC25XWDmWQJeV6KJxEQU9TIPrmSeLfxiJYTHB?= =?us-ascii?Q?LdSLdE04iqK3lIgCpMqefjgAYTzShae41THWq510jbVzjzCMK1A2k5QDbykV?= =?us-ascii?Q?uYGotkSkBhaiyJF28Jby9/w8X687nH14dFQHLyNDI0+qphiDZK956PKwMb9K?= =?us-ascii?Q?vOiSxa0T/7GRKSaorZ0+vR041M7qg4gz3eldL2LIRR+ipKDFvwSAxOo/uRDz?= =?us-ascii?Q?tltUkOr8xMK/CA4nwcEWpw1FgkG80D5Hd18CZuZQQpxNpDaV+J5KRSyHR973?= =?us-ascii?Q?0l4HyE/BD3doPzVRSJBnn1fS1467GzjDdRo5k+k85ylcRnQefTiCGGNCLPcn?= =?us-ascii?Q?BVzLVIItNjdWB2TMVa3rVg2XXmOcWay4qBpMzLg8Ge4vcRwXEGssdIwfFXZP?= =?us-ascii?Q?bnWCe3sKx4CJ84pDMJrzecQ79tx03lBqFu2RE6qAikOWUQ0TTOz1RSzsU9FO?= =?us-ascii?Q?E4OpqX56BTmrunXF7IIuYYUUsEC5yCvvPFy4t02692gbwk8HXK20ZpARsJNO?= =?us-ascii?Q?h24aVdDbVp+uyCFnOnPWPbiMJFYGYZkAjcrcdpp575rvKF29GUrzYPplcfe/?= =?us-ascii?Q?j0YJHqa3bsZYR+CdVgetjjmwv1S21nsn0UKrIz8mVoyjUKp/rn0ua0r0JN/R?= =?us-ascii?Q?4w6ZAUCdzHXbU6pq+GmunezgwJwzQew6iNSmLI7gQlWrplE8A9azQt3ioNPv?= =?us-ascii?Q?hT/K7uYb3JqLcQ3z4GMtiZZJ8ZAQYCHEEryQoTLkc9NbnACgcv+8q3usXoqZ?= =?us-ascii?Q?Y9rMhQc4RFBSlyUeBwQlNF2QODwCwqo+nhYpNomuBr2osh4Eh9I0RsEnmVVi?= =?us-ascii?Q?4jK4tibPBJwqljjQru+zbVi2JVU9bAPHtS9CtdLN5mx/Y80Tng0OT687hbNc?= =?us-ascii?Q?U36i3BB/yP5tWrJuSJmQqJaPmHQUq2gQYR2RtLc2TSLh1MJrHQa2HUuWTuxe?= =?us-ascii?Q?DgMHNnsLnQxp4loIpb4JPyerZGpJF7hxNPuXvT7sPYTbgKrMSKiyLq5Co9Od?= =?us-ascii?Q?DIRaAZgkQmWmBz0DukiUoFlmGBl9RoZAbz93sToFOWViSbD1GROJDMNOfp9n?= =?us-ascii?Q?lZ3bBfmWvMfrqghYTvgmcF7+nHkrOQsmnpCk+i8la8nJYekklwg0VE89p1un?= =?us-ascii?Q?pQsbz1ZnEJI7qSiZH5K3Dvl96V40KsNA9kIZ2ClDxS2h14chgc3gGqPyakgr?= =?us-ascii?Q?Myuvx7HLgLghbD+dW2I=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: f01f2d22-6c17-4fdb-720d-08db5196e24b X-MS-Exchange-CrossTenant-AuthSource: LV2PR12MB5869.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 May 2023 20:41:08.8051 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: PQWXhW9b/WNM2XhWIRQFQiRI8gtdVzZHvLADktS3Sp8/KVVQxJeEm35B6fPowOrU X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY5PR12MB4966 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, May 08, 2023 at 02:57:15PM -0600, Alex Williamson wrote: > We already try to set the flags in advance, but there are some > architectural flags like VM_PAT that make that tricky. Cedric has been > looking at inserting individual pages with vmf_insert_pfn(), but that > incurs a lot more faults and therefore latency vs remapping the entire > vma on fault. I'm not convinced that we shouldn't just attempt to > remove the fault handler entirely, but I haven't tried it yet to know > what gotchas are down that path. Thanks, I thought we did it like this because there were races otherwise with PTE insertion and zapping? I don't remember well anymore. I vaugely remember the address_space conversion might help remove the fault handler? Jason