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Mon, 9 Nov 2026 16:16:57 -0800 Received: from nvidia.com (10.127.8.9) by mail.nvidia.com (10.129.68.7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.56 via Frontend Transport; Mon, 9 Nov 2026 16:16:55 -0800 Date: Mon, 9 Nov 2026 16:16:53 -0800 From: Nicolin Chen To: Mostafa Saleh CC: , , , , , , , , , , , , , , , , Subject: Re: [PATCH v9 11/25] iommu/arm-smmu-v3-kvm: Add the kernel driver Message-ID: References: <20261015200903.2735565-1-smostafa@google.com> <20261015200903.2735565-12-smostafa@google.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN2PEPF0000A894:EE_|MN0PR12MB6344:EE_ X-MS-Office365-Filtering-Correlation-Id: 052168f3-9c1b-47cf-e8bc-08df3ebff909 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|1800799024|376014|7416014|23010399003|36860700016|261028144727099003|10067099003|11063799006|4143699003|56012099006|261021121427099003|261022075727099003|261022105027099003|261021135927099003|261009223027099003|261026140227099003|261102123227099003|261026121527099003|22082099003|18002099003|6133799003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: ZCTX0zLr47gHJcPHYTwZqvSZ0cSODxq0DwoEbbyvD2bctkLclvoFCmT5QzhtujTz/vMetUFJGHaD02jHzdA/sg9fAsTq45eLyWU7RKbtBfBM0+DjFNXRwEVk8KQU0krwKglVHE0UzToxZQ0MGY1glUVCKGktpOcf2EmnC/YcHhaMpatxg5bY8KT9K2KUDmZGDj5sJU9z0w8uR1zDdhW/d+pPWTqet+ugCN7oOt/3JDFGDO5L4EDQg9jyaadWwN36sjXVqifw26BAi4lkdiD1DtEhSjbUEcFuAkRx3NHDEF2L6zNiFDH+1ZaJPUlL5TuKuWcwW5bw8537vn3nivN/i6eXiZabc2bTXqEWIrqbtCotKZX5ZQrrg/oPiUMihDxgqUkZrVY0ZRUyyDekix9E7UEfPgbU1Rm0GAOvR6HueyX6Wcgl9dstC45jIJbzPu7m X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Nov 2026 00:17:14.5815 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 052168f3-9c1b-47cf-e8bc-08df3ebff909 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: BN2PEPF0000A894.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN0PR12MB6344 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261109_161723_806114_86EDAD8E X-CRM114-Status: GOOD ( 22.08 ) X-Spam-Score: -2.1 (--) 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=-10.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=ham 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 Mon, Nov 09, 2026 at 10:47:46AM +0000, Mostafa Saleh wrote: > On Thu, Nov 05, 2026 at 01:06:18PM -0800, Nicolin Chen wrote: > > On Thu, Oct 15, 2026 at 08:08:42PM +0000, Mostafa Saleh wrote: > > > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > > > +#ifdef CONFIG_ARM_SMMU_V3_PKVM > > > +/* > > > + * Two devices are involved: the aux device bound to this driver, and the > > > + * physical platform device bound to the pKVM init driver, which only uses it > > > + * for discovery. This driver keeps using the platform device, as it carries > > > + * the fwnode the IOMMU core and consumers link to, the DMA configuration and > > > + * the IRQs. > > > > It would be nicer to have a diagram or so to show the co-relationship > > among different devices and drivers. > > > > I assume the regular arm-smmu-v3 driver is a part of the picture too, > > when the pkvm driver binding fails? > > > > I can add some ASCII diagram. > If pKVM driver fails, no aux devices are created and the main driver > probes the platform SMMUv3 devices as usual. I didn't check closely, but would it be safe to do so? Is pkvm aware of the missing SMMU device and handling it properly? When pkvm is enabled and the SMMU device is supposed to be a pkvm device, should it not fall back to the main driver? Nicolin