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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 5D7A8C3ABAC for ; Tue, 6 May 2025 16:27:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:MIME-Version:In-Reply-To: Content-Type:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=3CeKdELFEtKqoD6jWMI+oFnn0WaIXtBwP1CwPrybM4E=; b=nJZUXBVMdIlhev3alfHaBWroE6 5McAuLebG2UNF+RVoTDqyCR3wdzT4cBTSvUJTQG4QjP+9wlVEG2hzPyQ1bpHAJ4wvmDG71tDHFI5a 7P/YAu5YRQFvO4JMDe1WvoBw4UmX8itpZtU3Zy0lL2aLCJlqOYEUUM5tWlVsCvuDk87PZUl6POqAA 4UutQCjoJLOYPy2XhuHFPeD6ezJ1PojYXLra8ang247At0guN989rKug/pxsTU6MGXcFCWA6+VajU 9lqfLcISPuCIxpsV9MUcJiVdjitaT0NPLfoORWJcOWTrsQ9UoJNlr66WGm1gGjNebVX62WRftvz0w Y6coZVTw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uCL8G-0000000CfRv-2Jdb; Tue, 06 May 2025 16:27:00 +0000 Received: from mail-mw2nam10on2062c.outbound.protection.outlook.com ([2a01:111:f403:2412::62c] helo=NAM10-MW2-obe.outbound.protection.outlook.com) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uCHpq-0000000BzDz-0ENi for linux-arm-kernel@lists.infradead.org; Tue, 06 May 2025 12:55:47 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=Tzd+eJHLwQILvqUBF2a/Bbrw1xU6G0yfGGBG5eJWQtxZeeq+Dj7EdHqF/uZr06QAZCiFwSniF4GcODo7yHk/YZB9eWwAxydFyJ4L5Dpb5taeuKkr56UR/IrwUy2sEDFfHQuPriVIsp31X3fxRAJy+d8MwPjpYRmRhVvj03PuOXTSsatzbsEEK8xpWdsvtpTIbaqMfnT5TgXjvPHUnZF6aeb3z+0LxMSNyzm99YcLR8xOqMj88XC3d8qFWlj76Oi/1vhHq/Ns6HI88xXz5LpffecwVcMg/t8156x7c8b5SnHgTrs4Du6poZN44VjxLn+JfQGW+5pt/IXcmgxdlbmDmg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; 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=3CeKdELFEtKqoD6jWMI+oFnn0WaIXtBwP1CwPrybM4E=; b=lpLEl2+cg2yV59cvrE4gRaAQI9BWA/CP0pXMzT5RzJd3F82/1SSdw5/g9Fw8ZyfhmJ/lki3RDtMDbmYgTSFLjOLK3nUyUuIm+G35n3jnuIe5M+7SeJTDkN5kOe3roOq/1lXh23BSl5G9577QUd8oAyJjFYZrXEVbD/e7PtfZWk+EoZ+oPW2qar6z9yGDiABNStPSvfWpBc3s9LDeaYbne/QwurFPKHge9W6xIH/DcR+CQxI0UNde1Ht9haQQS/+8EZdUez9l4nUCYflFqQLRk3ha3VoQlUjtkHxOM60lGtpcQK2ogUnKhMVIsKXaCn5MyBqcZ3fatJ9U+QySNZiwHQ== 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=3CeKdELFEtKqoD6jWMI+oFnn0WaIXtBwP1CwPrybM4E=; b=QCtssXsxO27haJDeSOQg3VhEKs7AhhVIa1OlAOLQKVYMyHzFhGcsYJdbgmTqOwLznkLh3onSajxiMo6eK96AcYCH4tVA9LiAlLWW9oKHM6u9T+i56Vt8RjVdVeraqrVYEGHkfE6TaIrvv2OG+nBdblxa6Uz6v1iGG5Rd98RS3LXnWcAy4GhV2m0BU9WCcf6oo2N8IIcmXEPoTh8W1PDLakWRJ6Sn5AggRRPHwULG5xHnwi4KFxrpBveA8McQfVejk8Q0CBPF+GrNNnDlkQFYg5sjpa433+mQCCZcKWgGA8ci3E+KwjLL1MMPCjox/ZCrdp+HzrH0QJj/uZFhbIrTHw== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from CH3PR12MB8659.namprd12.prod.outlook.com (2603:10b6:610:17c::13) by DS0PR12MB9347.namprd12.prod.outlook.com (2603:10b6:8:193::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8699.24; Tue, 6 May 2025 12:55:37 +0000 Received: from CH3PR12MB8659.namprd12.prod.outlook.com ([fe80::6eb6:7d37:7b4b:1732]) by CH3PR12MB8659.namprd12.prod.outlook.com ([fe80::6eb6:7d37:7b4b:1732%6]) with mapi id 15.20.8699.026; Tue, 6 May 2025 12:55:37 +0000 Date: Tue, 6 May 2025 09:55:35 -0300 From: Jason Gunthorpe To: "Tian, Kevin" Cc: Nicolin Chen , Baolu Lu , "corbet@lwn.net" , "will@kernel.org" , "bagasdotme@gmail.com" , "robin.murphy@arm.com" , "joro@8bytes.org" , "thierry.reding@gmail.com" , "vdumpa@nvidia.com" , "jonathanh@nvidia.com" , "shuah@kernel.org" , "jsnitsel@redhat.com" , "nathan@kernel.org" , "peterz@infradead.org" , "Liu, Yi L" , "mshavit@google.com" , "praan@google.com" , "zhangzekun11@huawei.com" , "iommu@lists.linux.dev" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-tegra@vger.kernel.org" , "linux-kselftest@vger.kernel.org" , "patches@lists.linux.dev" , "mochs@nvidia.com" , "alok.a.tiwari@oracle.com" , "vasant.hegde@amd.com" Subject: Re: [PATCH v2 13/22] iommufd: Add mmap interface Message-ID: <20250506125535.GY2260709@nvidia.com> References: <7be26560c604b0cbc2fd218997b97a47e4ed11ff.1745646960.git.nicolinc@nvidia.com> <20250505165019.GM2260709@nvidia.com> <20250505172813.GS2260709@nvidia.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: BL1PR13CA0346.namprd13.prod.outlook.com (2603:10b6:208:2c6::21) To CH3PR12MB8659.namprd12.prod.outlook.com (2603:10b6:610:17c::13) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH3PR12MB8659:EE_|DS0PR12MB9347:EE_ X-MS-Office365-Filtering-Correlation-Id: 6c8d0cbc-0911-4557-7982-08dd8c9d4bdc X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|7416014|376014; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?J1K4CRa0PkJ6ISwBb42RRV3oPZp9liwcw0YosnVGwSJzDsSfY0GiWd99/rH8?= =?us-ascii?Q?DClvOODQeRAxZGNhdCVwz4iggK5Bb/5NktSDJhVBqsJvobwJ7WD4H1OgdrRt?= =?us-ascii?Q?bzGNGcF5ssddswx+jffYhK9hFiLbpv4+hIdMIgPEuywBdOMi45AJhyBSU83X?= =?us-ascii?Q?P3n3csvJe4pcqKEsQiSwfUjbnaul/1EY1rkTXedYcu3qns0eboheHXaKwdMh?= =?us-ascii?Q?np7Bet/oHxtT3JbaAklb7E81+ec49rwj1o8JpnycQhkknKlpQf/cNclQJ5QL?= =?us-ascii?Q?xCsbx6Bu0zmRwX5Wp8SBZrdeVgxHRaXivDPIMgRAbDfH70WTrENkpW1MP22b?= =?us-ascii?Q?G5YB8Wif1WUdRF8fRFTBDaRWWUCSMEKZ2+Sce6rouSqidRud7CHxwtaEVlYQ?= =?us-ascii?Q?m0ongkO1FAJBh5xdBk0t7s4SdvapZ8P0qru096m/Luhwx62EoKZBPsEK0lpQ?= =?us-ascii?Q?xpO0FIEDR6kVBY+8oxoOcpPP97joEq8J2TNZYnkz0ZOp48y8Rq2xkxgDWRlt?= =?us-ascii?Q?5M8IRL7I255vA2+CgH6H7EGQ+nCsrfTks1klrJBOhzpQ+bc++E205IzcGGWy?= =?us-ascii?Q?B7qJnDF1gQ1N2APfDAb6yOjE5re32L9IhGBLdSYjkgWilsjC+++sSwW72IZd?= =?us-ascii?Q?c5a5ytbn6+EDdwyYW+LQTDFU4QcdJHPSjTVHzyR6xqo3sWIJF5FHkP8BV7A3?= =?us-ascii?Q?X/wxtgAuohZSwNSU/Dqf107V9Ksq1qP5P38B1HUkuXykHYSJZBfZ+QqGVwL6?= =?us-ascii?Q?iZlQ/XnBAS/SGornfm41IQRmoHMSkbIRDrYuvRN/ihxqjcNQPC2HTfipHwDY?= =?us-ascii?Q?1snK+6vqouUzE4eNgp0ztL+Fy/ogx6f6X9E2l0//BcCgxxoV67toEPVHZ9rU?= =?us-ascii?Q?UC0Y1c0X71j7PJ4SYQ6rvp2iwHWw6PCGjN3pA9bhvKk6/HAur+c3Lbh8FRky?= =?us-ascii?Q?qM0FhCGTd7aMrUM7sIKypoyFp9DEpbpDpoKmxurW9RgBuGygcBIK9PzUbgX9?= =?us-ascii?Q?GcJeSZ3ZWOgNcuNhbA6vCfmiWNHHq0pWNn4u2prNLtg7xtjSVDNP3uVadQg6?= =?us-ascii?Q?7A/XBZpOfZ4B3BlzOQCA4Zzn52SEotrFeHx77HmH0lPGs6MSHQ1IEmC07JZ9?= =?us-ascii?Q?WxN9CdDBPbNl+3CYYszvLtT0JvvWwjTJLnbNsin4KTzabjrQjzkziYsQVt1H?= =?us-ascii?Q?MZkYWujTeL70TdkhEhcHJ1yLf48d0JRFJesHMXgGVDu4r4xA/AAcBArzCQ/T?= =?us-ascii?Q?AjESc0fbS4Ppo1MIAIbeloB1qRh9M1lLcChuoeve9GryJDT+6sG36BcX96K9?= =?us-ascii?Q?2Dpz5QKXijwqvZLomieIWvPWOkaTr1Mn6xd/XLu1CsUw56pVVn+ItigoXDgB?= =?us-ascii?Q?g2TuFzgEDHNghRL14zs25NMZ9SJdklf+fH9f6+S4gKxroZFwIA=3D=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CH3PR12MB8659.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(366016)(7416014)(376014);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?BR0Ir4c8oBENdy4BpBaTEhq6cho2rRpWSkyIGVXXM1PnUdGUNfReeaU26tNf?= =?us-ascii?Q?1OBjmo/PEtBdjjKz40acj/9nVRESdlHS41eZ87oy+DnSKklvgont87YFKl3a?= =?us-ascii?Q?rZqWAkfv4XROYDgqpLkwqeG6GGW9RdlmMnb9ohXjh7I7M9VGcLSf2swZ1JTQ?= =?us-ascii?Q?Qyq9aL+DxobOUWnVVtenLwdbHZs3y20/qWqHZ2vJPmFAOZYNnCirUUHdimbi?= =?us-ascii?Q?THM2iABalkBZLdDZW2xomx3D1BTmUFYUmYw10LCK4QmAuMBgIbhXJVjfQOgQ?= =?us-ascii?Q?ZP7gZT5fWfiiMFO8JTfOUc/+WOmrval3eT1huYO/fep4/6jfC5YUjfNT96Ef?= =?us-ascii?Q?H7rAqziJajrY0AQAPdegXqPNQZTcGAZFBMpOS+MEaX6hNaLEt9j3b5HzFmAM?= =?us-ascii?Q?UXmZ62w22a1LVJ/4PoG5AYO2bTzwJ2WsnLzSFUrthZxkYG4z71VZe7Rdy4l1?= =?us-ascii?Q?0cZybBHqkeQgKFnenmYyFGPElRbSsgq2NS625gkBRR7HVIRIoATY1ckvBVkb?= =?us-ascii?Q?Z+9uYWUofyKAFKmASDFXYUBl2n/tx8/TvP2TNO/+tDA0RSFjeThDZZgwqj27?= =?us-ascii?Q?96lAH2mGV9K02bttPtwhyyiQIAmsG5hyOKmk5dQ5v91pS0M9hv9l0zFiY+5v?= =?us-ascii?Q?Gr/F0YtLoZfD5Q9j9gaaVpT0YLoUuz6WJdAH4JE7DaSPuhjW2QTs57/c9OPW?= =?us-ascii?Q?M7NkhsO4MVPg5N+zx20yJ3rJ8nMcEPHEVYeeb/J3yT4Yt5g+JWXgmGCHFvFZ?= =?us-ascii?Q?73MV0z1Zo/iamIOOQ0fOxvKE3jKv+UbS9ml8gP9ZY7XoDieEjOhb/65d7Yzx?= =?us-ascii?Q?x1NwQz//es8QUp/ZAzbAEag30j1p++Kx5UtrXEbUGO1tPaN37XjeyhtxjN5T?= =?us-ascii?Q?uk+pIX3a3A2gr2wcmvRCmvoUr3a/pinWlT5FU3Jt3Gc2/cmu2hIv7ehANsfa?= =?us-ascii?Q?L+RRPebrwWzIyCopF5JpoFzejuOqDNH9NGcrEARh101PuUXDrYKSWzrPQfQ8?= =?us-ascii?Q?blHEUuoTpcaYT/9A9WmSnjrccMiVv5VPata2bLAn/bfnJ1O27/Owz7Hc8AuH?= =?us-ascii?Q?0vQDOPSWeOvkg2zfUrIxPKHzYUyEqZ9J+2ANeMtwhyRL/wCN8scKu8syI+X2?= =?us-ascii?Q?hHBYpJdCjkmk42psRYxyXN8cPOFkXidTm1VE9ogQo2CTFLdm8riTlZ1thhgz?= =?us-ascii?Q?0PHk8EOg/BQhOPzBjpSnazo6TZlxvNZ52UiJd47JWqEBRX/fQ75D0gFIsvAK?= =?us-ascii?Q?qvuYc+iifBWnJzWp9bbb8+DTlpu/D8NT2vWUy0DeSCRY7ia5CFxWpJNwHWz3?= =?us-ascii?Q?8GLyxjAZxTQxsLCfiOwpeMatwsuwSCLSTbKSj5MDrIKqr5gUYb1xSodGlWye?= =?us-ascii?Q?0lgUMDXpPhK2cUJE+HJUqNOJe5pkMcKeTtNMhTgsrFxurB6hz/eTSzl9d8hq?= =?us-ascii?Q?Zn6mx3hXqLoeAWJhvNEv+FmQOSPJ9NmqG9KbAqfXP/crUzn/TkUE6LYb/Upp?= =?us-ascii?Q?kfaundXd/3uxsnynkeRgCRX590FIJ2EKC0UXxpnYj9m9ifMIGJaYCWcE9EBi?= =?us-ascii?Q?RZGkMgRuyF93s17iUtRcxwMZ7AUYSHo7na4IJ570?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 6c8d0cbc-0911-4557-7982-08dd8c9d4bdc X-MS-Exchange-CrossTenant-AuthSource: CH3PR12MB8659.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 May 2025 12:55:36.9083 (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: ieiGCYz1gUq7qnDWdiPOiLqCfkRQ2SE87Q0MER+NPPXYuwtobLsMHtioWpjljSPB X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR12MB9347 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250506_055546_086988_A31A386B X-CRM114-Status: UNSURE ( 8.61 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, May 06, 2025 at 09:22:55AM +0000, Tian, Kevin wrote: > what Nicoline proposed in v3 adopts a similar policy. So it kind of > makes sense to me, except that we should not return -EBUSY in > vIOMMU destroy ioctl. Instead, just decrement the reference. It forces the userspace to unmap the vmas before it can destroy things which is not so nice when it is easy enough to fix up on the kernel side.. Jason