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 CA5A4D2FEC8 for ; Tue, 27 Jan 2026 17:51:43 +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:In-Reply-To:Content-Type: MIME-Version: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=loP3z5G593SBJMbOigdLWtpGpmlyccRB1f+6XAa+5aA=; b=nbQmg8xH5hW5EPljkveImlJ5qe VhDSa3IUPiWoQhpYbMnB8vSaKOFsUTY9Ei4xQr4I6IiTbHRmODXCq7Tz2GhVMgv7GEOZO+4IRXc4A Q6bGnh5IxN+P91vmI744bUyaQlf489sez6k42CLjbmUp/LpT03VGaMyxTE1CUh3WdH+htySzRRAQg ZQeQnvgMVIWy9mjigZNQAup573ndAbKey8fZsWAIZUSkd3EsnKFUT6BpKUYR/yqYmBVyfUeDYKXrZ sFZb1tfkKD3ONoW8u63Ocb2SgUJVxJ03/NgclL4Gn+qh6hQ7MB4hxy4p8kH0mFADod8rIVb1aU1Fp TI4IAENw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vknE1-0000000EkwO-0wdH; Tue, 27 Jan 2026 17:51:37 +0000 Received: from mail-westcentralusazlp170100005.outbound.protection.outlook.com ([2a01:111:f403:c112::5] helo=CY7PR03CU001.outbound.protection.outlook.com) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vknDq-0000000Ekva-2dxR for linux-arm-kernel@lists.infradead.org; Tue, 27 Jan 2026 17:51:36 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=kXmJAtAr2XGR5POYWSTMvWKy0jKOJ0xZvlcBV7LYnq2fIBZNS2kbx+oHGKEgOCgf8lmFAsEces8Vi5C7RSGdPvh565/ebIR1UgPHgVcYbu7kRX9ilDR552QTa8O3O2Z/Dox0JbClFX/vAcsrrD8VzY2V3tpR3Q85WU+LmWKJHPqsnYmljqTJbsBtNO74LdAf7+tqnXBaEOZXPjZniufAz8FGaeGmWCC9VCNw211gVU5XZbFXtHybpQIP6m+7Hy8kc6N4N0lC19KuVu+Lfqvzl6JCduT8KNQb2FrnIOJxRMXxESIPaLjJ8x+8nXmK9WzAty3HmneDftM4llTpbvUfeA== 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=loP3z5G593SBJMbOigdLWtpGpmlyccRB1f+6XAa+5aA=; b=PumyF0iLgFUC3RK7kCXBfDbXwo3ilJ0lG0rLOqOTQ0o2ElRIJho9QjVIIucwy8IYzdUu0CX7XQH8w7RawnMCKjeh2BSJGzSHWFwXgpHn7cBGV+TtXx/OAl6Kc8JD8O68KSXxThOIKDj3rwNKuv01eTkUCs5Xc276SMA7UdWsxHk6SCCIBaLe0UZ44/mBRbsweTNFIOJe92NvuzIYOpWPuL2o9Ycd4NTd6rCS2i1cDglsKRRSpwL11v+XISeR6OQIcFrBOq587x6G5x1jT32mwjDWG6jyjCakLVXJcUQPYEdrkVFG1Db5GzRxNkR2V0amU81zzxrYrR27l5Hs2T60SQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 216.228.117.161) smtp.rcpttodomain=kernel.org smtp.mailfrom=nvidia.com; dmarc=pass (p=reject sp=reject pct=100) action=none header.from=nvidia.com; dkim=none (message not signed); arc=none (0) 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=loP3z5G593SBJMbOigdLWtpGpmlyccRB1f+6XAa+5aA=; b=uB3+vvLfRmZ0i1MGd+vdzcCvx8BxfO0WSmhVX3/EwaPygFIsLARbiuV+TUTyP5gt+k91EmSECYb8BCgHpnXKZQzNsnnKfzwdDdb+mFFeA5XKJL4UBc5r4u7vzIhZP4IDCoZiaOJld9RVDl3F1D7TlOxeugiYOyXj25vDAd7uTnvIzNLI5O4i9ouLnWgF1qBF8L556k13cMbgbYaCn/vErt+1y5wW/xHtnb1n109jzkp9a4EYXgWvtg0eyoq35k++JpU3ppsLayOJW51lvGfugq06Zw4tcQvp2iXgEdMFPsEd+50WvfKrfMR+EhNffajKwO7GfUaJrZOy0X0AuR5ihQ== Received: from BN9PR03CA0952.namprd03.prod.outlook.com (2603:10b6:408:108::27) by PH8PR12MB7448.namprd12.prod.outlook.com (2603:10b6:510:214::11) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9542.16; Tue, 27 Jan 2026 17:51:20 +0000 Received: from BN2PEPF00004FBD.namprd04.prod.outlook.com (2603:10b6:408:108:cafe::79) by BN9PR03CA0952.outlook.office365.com (2603:10b6:408:108::27) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.20.9542.16 via Frontend Transport; Tue, 27 Jan 2026 17:51:16 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 216.228.117.161) smtp.mailfrom=nvidia.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=nvidia.com; Received-SPF: Pass (protection.outlook.com: domain of nvidia.com designates 216.228.117.161 as permitted sender) receiver=protection.outlook.com; client-ip=216.228.117.161; helo=mail.nvidia.com; pr=C Received: from mail.nvidia.com (216.228.117.161) by BN2PEPF00004FBD.mail.protection.outlook.com (10.167.243.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9564.3 via Frontend Transport; Tue, 27 Jan 2026 17:51:20 +0000 Received: from rnnvmail203.nvidia.com (10.129.68.9) by mail.nvidia.com (10.129.200.67) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.20; Tue, 27 Jan 2026 09:50:58 -0800 Received: from rnnvmail201.nvidia.com (10.129.68.8) by rnnvmail203.nvidia.com (10.129.68.9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.20; Tue, 27 Jan 2026 09:50:57 -0800 Received: from Asurada-Nvidia (10.127.8.14) by mail.nvidia.com (10.129.68.8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.20 via Frontend Transport; Tue, 27 Jan 2026 09:50:56 -0800 Date: Tue, 27 Jan 2026 09:50:55 -0800 From: Nicolin Chen To: Jason Gunthorpe CC: , , , , , , , , , Subject: Re: [PATCH v2 10/10] iommu/arm-smmu-v3: Allow sharing domain across SMMUs Message-ID: References: <2882c7b6dcec7cf8bdc08bd4fd9f4c4373db5469.1769044718.git.nicolinc@nvidia.com> <20260127154111.GK1134360@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20260127154111.GK1134360@nvidia.com> X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN2PEPF00004FBD:EE_|PH8PR12MB7448:EE_ X-MS-Office365-Filtering-Correlation-Id: 42fc9683-021f-4b07-c4bc-08de5dccadbe X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|7416014|376014|1800799024|36860700013; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?VRB85TKfJQ+MVhojbq1f/45pI+mupzQyXH747AnPdFy3o3RfZUDJAj9bm0W1?= =?us-ascii?Q?v0x2hCbl2JRQXVm2boMvzx4N0T/rMEFrmgyW+io8WObXGfbpbwncV7NO3sNw?= =?us-ascii?Q?zLjtFEwbroUCDGpTsqopLcQVoTK9eNmNNJsGnq8WF8gklrR2TlxrO58vPAzP?= =?us-ascii?Q?c7l0cdmU550OwGFb2qvc/SRHCdpiz1H5XzNbzPTMLJdoQ8pBHc1C9Frb1KkZ?= =?us-ascii?Q?CJKF9QXP7DsAbX9POU+7/Pu6sfKwQwBxQOLH15ubImVlqbChfDn8VC82aUs7?= =?us-ascii?Q?mTCRR2DasSjo5hZ7frXbV5GaGn/gHOq277Ye4TKd40HMQ0VnDZF/r2Y28Ivv?= =?us-ascii?Q?hQgLkbiG31QqCULd6N1mijZ2clqUS9qlR8SBUkU8vXceTIbr/63qptHbKaG8?= =?us-ascii?Q?iWNpHuxIAKgBlTXg3PCnbmdTKYATD3g5sps3vApgNKa7mPuyydTfWGYbGmy8?= =?us-ascii?Q?Fkop71drX52vv/0fJ83p96CmFSGKPm42r3Var7D61dBPPdDhGuZjHiYhpUsm?= =?us-ascii?Q?3PTpxXWGAd+stYAuv0X6cVGbIBqK/jgW11uv3oPzk/C+gLfEX/mHqmv0u8hX?= =?us-ascii?Q?q8YT88Oh0cvq/EhyUeMOji+dRGn3naBS01TwGo0ZCfNL5lGRhBwy5F8k/aFZ?= =?us-ascii?Q?NKYA65H+4YFiVqX/CBENPsTd06O/JMHRYHg5RX/R5Uyv5NGnTO/Kpqb72yzs?= =?us-ascii?Q?POZJKm1G5F7ZWwL3wYIoPBlQ/PVpNUuRkca0pBpqC+z6gZrZvQrKxKSJlmNO?= =?us-ascii?Q?sCeNNpwnE+EfBWXkMvywFDROAL3UpLYxrjKT/27xN6qyGU/OEkHjUrF/Tq/s?= =?us-ascii?Q?aN+z1TJTLThzw/VrC8RDD8roNqlWzFy/X0cB78qDkK4ljbFUi/rtJzVB+UcU?= =?us-ascii?Q?36HxLqG/8EXAjA++5vp2kHYXLVuCzaPCVx09lEDOiavIUnxh+WfEt+d4L/aJ?= =?us-ascii?Q?AhOzxAEhsFB4oJEMqtkBz56OjiPXE5SAMAvLqQNVK1h0/jegcyy5Pj3lAFTI?= =?us-ascii?Q?SeKyV11GaCqn3DrbjzHLCXS0QGdceK9ALN3Fzj0tMI3Ka2pjWZrAu8Y2ICNu?= =?us-ascii?Q?it/8mcXlHq5aHc6ZMlgtq6cDAZlRDFyWFIQGR715HhVFp8i104CmlISHWh/n?= =?us-ascii?Q?NdVITBxU20kEeZ+GJhx8oQfqzhAnCwQa9C3fbatWYg0A8m9vFmLOGBkjbr+V?= =?us-ascii?Q?7j8dWiV+JmkMQQq3qEy6d48txeuaH5TSp6iD8jtvsK2dFvNzUYmkLiAAFKZY?= =?us-ascii?Q?49dpAeDT+l+UgC8V6vKC2v78asIbwTRRhadUDKHVAjaOf8FbrtkvbF1fjsZB?= =?us-ascii?Q?P9R6gd+k0g3qUyjGkx0ztCHhKiv2tRfeF+zcuXGKRG1T508XPQCkhc4tVha4?= =?us-ascii?Q?SciINO3gveoT9n4dlw1KfEflnkX6DdXqKNEvwRGSXCeONx4LvNWVWEQmRPeH?= =?us-ascii?Q?9Zs0inPk3i8OAkYeKyz1M4etBs/8Y+HOERdPHW9heVR51EFfBQd1dKkY908x?= =?us-ascii?Q?k8WBEKaE1H1xSpDs3J2VJVtTskxqs8CkZx+oEBaz6t5CB2YGV/h6oSG0rzjY?= =?us-ascii?Q?v+m1zxjDLLzPo4I8s+XItZIsh8mbclUvNB9j/977yyiQTGGS12ZjQ1jtlSum?= =?us-ascii?Q?4SVhQpeaD0Nr4NEAjijEj0QN7sv5G+/Y1zwveupz6o10XiBvMXiXyG8BMUZr?= =?us-ascii?Q?Ww0L0Q=3D=3D?= X-Forefront-Antispam-Report: CIP:216.228.117.161;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge2.nvidia.com;CAT:NONE;SFS:(13230040)(82310400026)(7416014)(376014)(1800799024)(36860700013);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 27 Jan 2026 17:51:20.1021 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 42fc9683-021f-4b07-c4bc-08de5dccadbe X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BN2PEPF00004FBD.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH8PR12MB7448 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260127_095126_670978_FB2ED8EF X-CRM114-Status: GOOD ( 22.77 ) 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, Jan 27, 2026 at 11:41:11AM -0400, Jason Gunthorpe wrote: > On Wed, Jan 21, 2026 at 05:24:28PM -0800, Nicolin Chen wrote: > > VMM needs a domain holding the mappings between gPA to hPA. It can be an S1 > > domain or an S2 nesting parent domain, depending on whether the VM is built > > with a vSMMU or not. > > > > Given that the IOAS for this gPA mapping is the same across SMMU instances, > > this domain can be shared across devices even if they sit behind different > > SMMUs, so long as the underlying page table is compatible between the SMMU > > instances. > > > > There is no direct information about the page table from the master device, > > but a comparison can be done between the physical SMMU that the domain was > > allocated for and the physical SMMU that the device is behind. > > I would very much prefer this works by inspecting the cfg from the > iopgtable.. > > You can get it by doing > > struct io_pgtable_cfg *pgtbl_cfg = > &io_pgtable_ops_to_pgtable(domain->pgtbl_ops)->cfg; OK. I will make it a detailed scan > I think it is important that the domain->smmu pointer be removed as > well I will try that too. There are smmu_domain->smmu validations in two SVA functions, which presumably might be replaced with this can_share() too. Thanks Nicolin