From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 07E10606A329 for ; Tue, 20 Oct 2026 14:10:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=RfJM/7ey; dkim=pass (2048-bit key, unprotected) header.d=Nvidia.com header.i=@Nvidia.com header.a=rsa-sha256 header.s=selector2 header.b=W+1Tpzxb 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=IAF6xD5cIQqwIJ5T8c6143w+PZ8zjeS48r8fgDdrypQ=; b=RfJM/7eyfCOmkvm26xSRUpjcSH OWESc2Kf318noLxOBy3VG1ZbpDgFzqxbrc0qUzU9gxpRNLATWCGjgag7gYaMR0Zpkv4vI15270nth 8CL62HSErZaVvyqkDd7vPXylRoSucMvXF7jHQ/Jg4JYnCPM2r1EWyw9apr5fbu7747PSDEisKPJPQ wlcViqXbDuzJzknneO3/WGlkBI7nw2HUCwL4Uzh71jG6tmr8XgQjQ0eZ3l/DIZeakhWCvMSZKyQTi 9D98GnP0T6tRM24Zq1S8sXrvrahD2pRm5O9pQBWy9kEur4pGc69NYq3xUlrQ1PXC1KR85tbs+qC/k 6vg2xp6A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xJAXM-00000009t3P-1vks; Tue, 20 Oct 2026 14:09:57 +0000 Received: from mail-westcentralusazon11013013.outbound.protection.outlook.com ([40.93.201.13] helo=CY3PR05CU001.outbound.protection.outlook.com) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xJAXK-00000009t2m-05qp for linux-arm-kernel@lists.infradead.org; Tue, 20 Oct 2026 14:09:55 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=XEFRx3FpCxoKBdz0GxWNR147hNCE5M/5SLCTz7DEgTRMVQpVBIHZK6lseTTuph0wuW4UGfu9qqQCL1KhXAbWgMTSwCZtWujB3Qwf8U9Ay9+x+/UNxzf1B2xGTPeBmJ/WTzvAzQFmItOWDRKzRdop6nYjjjF9cBs9fRMlZG05fxZEzDobiisB424mtUxeglgNP7zpa/a19IHuM/dscDgArGrZ3iMS3fcPRDD6PYFkv4c8HsKrWM/JiYCXKHZ/TFsL0MmYfeUZYYCFbke/FWZBj7V2WU8i3FAygaruNQTBVrR8HiFvrfPJjmHmfg8W6qgaAnYmCULJTbC2YvVteEQMng== 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=IAF6xD5cIQqwIJ5T8c6143w+PZ8zjeS48r8fgDdrypQ=; b=lwjoZ/hOH6b6ccSvkEh9HsbttwrzFJQMNR4glj9szOAfOy/tfAuKj4CmYh+3nf38fjnW5EHoiOuFnCSZR3M0xQ57502izd8UMWqPqCbKRBtE6Snh0YKznqzaV4a025hKzG+qRw2THgp3aAAnE5NXUcacIyttOo88IuEmhbB80R9eKYeWQhWo5grLg2VV929zceu/fBJ/zJN+Is0QoafUyT3/QuJQDOLOrq42mBT3+7pDUgsY92y/nk6A5/BoGz5ySD7wGCMuL/MbGRoq7Dp4asWx6jpNd9IHG7Il4pOqPYGBbxrFodXDH6rwfGsWQKQ6VV1oi0W/n7dGaENi+YJcKw== 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=IAF6xD5cIQqwIJ5T8c6143w+PZ8zjeS48r8fgDdrypQ=; b=W+1TpzxbsEfaA2Ml+KUj31px5w3L3wjRZYyB1Ixl9B/8VsF9dCduQU8hC1zEe2tzgMaMgLnnKttj9d45MUDyKUP6fx51va/oNamLdYijvNbZsECtJjtt8xjcqJhja/CQiRzkKHvXCgno3cuJFgyqGE5ld6ET967VKM1SwQlHTTDk786SZY/vgW07tNMuwDH8YM2gzqiya5vPHhm8+QmXM31TkNcCuvPe+OqUHuF2rqae3BYYVNm6JxEqXM8pLWqGEwqIjdgr9Gl0JnwwHq9MxjzSZnYZeqrpkCrbj2xK99B3bC+rqkhQiaDhaFckZOg1IViwM0YndrqsGDAko0C90A== Authentication-Results: mx.microsoft.com 1; dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from CHBPR12MB731189.namprd12.prod.outlook.com (2603:10b6:610:33d::12) by SN7PR12MB7978.namprd12.prod.outlook.com (2603:10b6:806:34b::9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.522.19; Tue, 20 Oct 2026 14:09:45 +0000 Received: from CHBPR12MB731189.namprd12.prod.outlook.com ([fe80::b0e5:123d:fe06:e10d]) by CHBPR12MB731189.namprd12.prod.outlook.com ([fe80::b0e5:123d:fe06:e10d%6]) with mapi id 15.21.0546.012; Tue, 20 Oct 2026 14:09:45 +0000 Date: Tue, 20 Oct 2026 11:09:44 -0300 From: Jason Gunthorpe To: Ryan Roberts Cc: Greg Kroah-Hartman , Arnd Bergmann , Catalin Marinas , Will Deacon , Mark Rutland , Marc Zyngier , Oliver Upton , Alex Williamson , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Jean-Philippe Brucker , Oded Gabbay , Jonathan Corbet , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org, devicetree@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-doc@vger.kernel.org Subject: Re: [RFC PATCH v2 12/15] vfio: Support VFIO devices that access the CPU MMU Message-ID: <20261020140944.GA3008132@nvidia.com> References: <20261015142552.4128028-1-ryan.roberts@arm.com> <20261015142552.4128028-13-ryan.roberts@arm.com> <20261015164421.GD13920@nvidia.com> <95e0f9bd-0203-4c7a-9d09-622593bb3d4c@arm.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <95e0f9bd-0203-4c7a-9d09-622593bb3d4c@arm.com> X-ClientProxiedBy: YT4PR01CA0295.CANPRD01.PROD.OUTLOOK.COM (2603:10b6:b01:10e::6) To CHBPR12MB731189.namprd12.prod.outlook.com (2603:10b6:610:33d::12) X-Archived-By: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CHBPR12MB731189:EE_|SN7PR12MB7978:EE_ X-MS-Office365-Filtering-Correlation-Id: 00731ed5-fd8b-4d9d-cf5d-08df2eb3cb07 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|7416014|376014|23010399003|56012099006|4143699003|11063799006|10067099003|22082099003|18002099003; X-Microsoft-Antispam-Message-Info: Cz7BeM2k8TLaYCRI1wcVMG1vH3fs2+zCxx5jEUAxTsGXu7jXURwDzkbUO32iPvXgH/gNPhMVcU1rVID+1EV97Lv1jhKnVJ4RNPw/G0q7OOcu+O978/os12QkZbnUzbDX+I4d9y7TOGuJFKF5UO5JuxRUVqwaKw6FiG4kxxIsldoBbLG87vKhMRMW0Em29JK9OafDPpyj7yXvj4EY9IlUCsTPO/BiFUA7OrrdTiUBcLYbwO0F806pa1sjC15ACFm2vez6md0mWWLsN4yLonJUGDc8Z6sCZONTLOabIYY/GJoATIJ8sptlYJowG4i8+U7U2DQZuPJGc61UHmtwEHIzu+O60NUU9rF2PAzHiETKb42tsRbgcboiOBMV7O6uFBTO59Y0PeWbN2ce9Fu/K7j4tnLPWFYsyG3uQpLF/sozb+v5tXJu5ykhfZgxmGz8a4uGh0qkTekOjWJ68ZlMFM1EAfdBMI6ORqH4xIG9ug7fbUeF12FAolABleQONvvGIxw7Jx4eWjHxaY8yBfv/0XYFiGSi20sooN0yUYEkhm+NJP9C9TVUmKG95j1g+oHA/RzrxFOOBTcQTeReNGInm62kGsvrVd1ZS84g5Jj74UsgEV6JFq7HAoEzp3yk8MXFJ60E44vn6hso74Z4HKTGOyWXZfQp9vpWYlkHVR567+0qTFM= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CHBPR12MB731189.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(366016)(7416014)(376014)(23010399003)(56012099006)(4143699003)(11063799006)(10067099003)(22082099003)(18002099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?RbyNzpgHf4nBHZ0rmqq+8dp14yfsOCAN5A7BbBVb5oQlZ7TXCyBFWTdOPcTi?= =?us-ascii?Q?CrYGMD9L5tqjTjkrHytRKYwJ7MEUs6qJR0S/Zt+klnlVn9WBYvOGbQHYA9zq?= =?us-ascii?Q?L78MUywrzWMdFcwOerjNMU2h3RjWFp/1ht9FYILCLCVx4J8Qi6BLoc3J6uzj?= =?us-ascii?Q?4iro8pTblpcxnouP3i8Mp76GV4vTzP0xWjmlv9MPHPgPv45wV8/jsdvJ1BqB?= =?us-ascii?Q?asCk2zcD38m1iYq+dZYsjJ1CzxGkoPNB3MVdsZmwXJDt1NdE4o+2JRkUdDHR?= =?us-ascii?Q?LPApyRdwCiO2dqS2lgRrmybPgCJjb3XsXMU1k2uLoMezGomniqPFRNRYhiRN?= =?us-ascii?Q?olnyZeHNcszv6F9sOt/tOowVjwHXdwoU3MCIERucwoqRn8FPjrAalY7aIxG7?= =?us-ascii?Q?dsKdZmv+zjsDm8t/3e501gvN6RUR5rKgZCM4MByhOaKbuLIsmRCPzHWkG4Mj?= =?us-ascii?Q?kyRoT4QVNDoF9EDdXJy3uPU8RvIjq1tM+17eUxjrccQWgJlrx2dsnL7LBUrM?= =?us-ascii?Q?QYccQO2m+9weSyTzd1xbbQ7KE92HV2It5Y3yDK0rIRUUD+xNIgRNBXXb5plp?= =?us-ascii?Q?FF/gp1gF41g0EtBeMm57BM00EWOkrxM6WWTggbFaZtwNMkBELeJLEqOE+eWB?= =?us-ascii?Q?/I0sqVj9Ufkn3YY6f6RA8zqKXg6WzoWs8PeVPzeRcW3I0BUxMCqun9CH2HBi?= =?us-ascii?Q?ce5i5eZb6l82RdXp/3N8/OvlmK11CCZM+HpUyybqV3Tu6OLd8OIlZ9FWROCB?= =?us-ascii?Q?6m6pMQwKsYe7O78DkDGfX1DKaF2EdiY5/tmLvrG/8cAkLE2SPd/AAgyXI2OU?= =?us-ascii?Q?Z+jd2lXpwPYZekQlhDCjjfFTP5R8qnxiL7yW8RK7DYz4KS2bo0gcvLWiVbeQ?= =?us-ascii?Q?b0YkRMS98C50RMzi2bk6qcFqBvKpOqQQg0yBv7Rjwe8A7K6QeW/k+2BC7Dpb?= =?us-ascii?Q?hqU+x0xsAwtSwQA27pFhchGpVa1qDKEFaIpnOzcnu4nvUSUcdQoVHAT1BVOl?= =?us-ascii?Q?4R1CM32x+fJYLe4vMvbBmLOnGEEDA9P46ByUs00EMLGwkZQEMqKooj/ErcQu?= =?us-ascii?Q?Kn1vl8rvugFy2G3N39LoAHh7lQSi/DUqxemP7fT/bp8FwheR0efQAzyiSkmh?= =?us-ascii?Q?Q09EZjyIO7nclvrc+w5wUkSXI766nFaJUW9vXPaR/tJPsBLS2KFOp86AFzNt?= =?us-ascii?Q?TiEqCMaFpIidHLPofWcde6LeOTBJ/TK8TSpWo58KjNoAizzhfAd2dXuG1X/Z?= =?us-ascii?Q?WK/zYwz9Go9IAK1+4ZTuD9C8PUEWjZShkUJnEczVdroqlWzjq138g3sIT8tm?= =?us-ascii?Q?WEFzQ3YGZI4nL7CCEnu1G6sdVnwnITWXi6b18zyQPFsiagilw3YiE1IoH0jN?= =?us-ascii?Q?oTlKwXmlRdIOpJbdOekjc5Bm/wU7ZvgMNN1Ln+8n/8Y36NToP+2h7fLujjHj?= =?us-ascii?Q?qGKNYJkVpZcrykrYCVwZTlaM737Ach8nmAQ8Z84QyW2UNcnFQy6OXQMFZR3Q?= =?us-ascii?Q?TvSgu8hjUCUwE59zSCM9y3Z1bx2kgvkN/M37P2uZU3fuTyjQwEzSxzBwJeBz?= =?us-ascii?Q?yOc9ZBo524xv69aFddCRpaMNKHv0RdQhyUSxBYAaLWl6uRnQugKFjHTRURgP?= =?us-ascii?Q?+DovbPiRd4HphqfdnBSBT5gPBmapPMlP0xR9eXz5cR3vt9G7aC2bKeCVw+5n?= =?us-ascii?Q?5e8ysMQjtiTnZPOvEcdELx9eg9Ws+xNwnkG4g+ao9ETHXanU?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 00731ed5-fd8b-4d9d-cf5d-08df2eb3cb07 X-MS-Exchange-CrossTenant-AuthSource: CHBPR12MB731189.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Oct 2026 14:09:45.1097 (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: b0/fzE02P456IsXRnIUoxWq7jQnhLycnba1Cjf+inB2OpAFE7rqieT3Gsr6Gmouk X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN7PR12MB7978 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261020_070954_064462_CA629666 X-CRM114-Status: GOOD ( 16.72 ) X-Spam-Score: -2.4 (--) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" X-Spam-Status: No, score=-6.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Tue, Oct 20, 2026 at 12:51:26PM +0100, Ryan Roberts wrote: > > However.. you still have to affirm which single mm is the mm that the > > device is going to be doing DMA against. The process the opens the fd > > should not be forced to be the mm that it gets linked to. > > What is the mm representing here? Ultimately we want to install the KVM > instance's stage2 pgtables and (pinned) VMID. We currently get that via the > bound KVM instance (which looks like it still works using the cdev interface?) > > The guest will then install the stage1 pgtables and (pinned) ASID associated > with the relevant (guest) mm_struct. > > Do we _need_ an mm association in the host? Ah.. I see, I didn't quite follow that. OK.. Ah everyone else doing this is using iommufd with a viommu to establish their connection between device an KVM. eg Jacob Pan's series. That's a probably a better idea to stay aligned with the common path. Though your reasons are a little different.. If you manage to get pinned VMID out of KVM then we can implement SMMU BTM as well! Jason