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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 BL02EPF00021F69.mail.protection.outlook.com (10.167.249.5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.428.7 via Frontend Transport; Wed, 16 Sep 2026 18:39:56 +0000 Received: from rnnvmail202.nvidia.com (10.129.68.7) 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 15.2.2562.49; Wed, 16 Sep 2026 11:39:21 -0700 Received: from nvidia-4028GR-scsim.nvidia.com (10.126.230.37) by rnnvmail202.nvidia.com (10.129.68.7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.46; Wed, 16 Sep 2026 11:39:12 -0700 From: To: , , , , , , , , , , , , , , , , , , , , CC: , , , , , , , , , , , Subject: [PATCH v5 21/27] vfio/cxl: Exclude the HDM decoder registers from direct BAR access Date: Thu, 17 Sep 2026 00:05:34 +0530 Message-ID: <20260916183540.3813685-22-mhonap@nvidia.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20260916183540.3813685-1-mhonap@nvidia.com> References: <20260916183540.3813685-1-mhonap@nvidia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: rnnvmail202.nvidia.com (10.129.68.7) To rnnvmail202.nvidia.com (10.129.68.7) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL02EPF00021F69:EE_|SJ0PR12MB5661:EE_ X-MS-Office365-Filtering-Correlation-Id: 21805d9f-38f2-490e-20ab-08df1421e7f0 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|23010399003|7416014|376014|36860700016|82310400026|11063799006|56012099006|10067099003|921020|22082099003|18002099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: YDRUhhLGSGfYXFF/MCK2Wep9Ztd6qPuXBOJ0lskKsoVKY7kgTa6S3WYo86V1w+Qnl4Hpoy8DVGazQHpUERQT7PUHV/680nb7F7t9lo8zRuA7K9g3zcTVPKS8pZQ+2G++HxNMCjMIzmT87v3uFk8+GoeCASdZhj77iRbVWgKJYsuRAGHT9QYb6nFYxsUTWQTXNAkQNQF2fMvNGKYp2gJSrCaA9CS5M41ArF6SmB+Hn9sTPakV8lYDCRqdO8tokZHa8B3IqNeWFfilXfCzwvs/cjw4HYFHH79Dngl/kOFKYtEocXKyBTvtSo83/u95ATnZ0fRxHAUrXblhN8kH2F2ocTjaqioCqYd3NljqdlMMzIk2fFc3FWmmm85Fxijgk/ZNTkw+KzfKoNE/2a3KJGutptiTV/3ow0vxzrQGfW1Ur2iis8jgPa8jf6WwUlCOCBe0 X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Sep 2026 18:39:56.5777 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 21805d9f-38f2-490e-20ab-08df1421e7f0 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: BL02EPF00021F69.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ0PR12MB5661 From: Manish Honap The HDM decoder register block lives in the component BAR that vfio-pci owns. The guest reads the decoder only through the trapped, read-only decoder region; it must not reach the physical registers through the BAR directly, and a host read of the range through a kernel mapping could abort as a fatal host SError. Add the block to the generic excluded-range list with VFIO_PCI_EXCLUDE_MMAP | VFIO_PCI_EXCLUDE_READ | VFIO_PCI_EXCLUDE_WRITE similar to the MSI-X exclusion. Assisted-by: LLM Signed-off-by: Manish Honap --- drivers/vfio/pci/cxl/vfio_cxl_core.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/drivers/vfio/pci/cxl/vfio_cxl_core.c b/drivers/vfio/pci/cxl/vfio_cxl_core.c index da04776356e4..37e8a3b54cfb 100644 --- a/drivers/vfio/pci/cxl/vfio_cxl_core.c +++ b/drivers/vfio/pci/cxl/vfio_cxl_core.c @@ -435,8 +435,25 @@ static int vfio_cxl_add_region(struct vfio_pci_core_device *vdev, u32 subtype, static int vfio_cxl_open_device(struct vfio_pci_core_device *vdev) { struct vfio_cxl_state *cxl = vdev->cxl; + struct pci_dev *pdev = vdev->pdev; int ret; + /* + * Keep the HDM decoder block out of the guest's direct BAR access: the + * guest reaches it only through the trapped decoder region, and a host + * read of the range through a kernel mapping could abort as an SError. + * Exclude it from mmap, fill reads with -1 and drop writes. The list is + * cleared on close, so re-add it per open. + */ + ret = vfio_pci_core_add_excluded_range(vdev, pdev->hdm->hdm_bar, + pdev->hdm->hdm_offset, + cxl->hdm_len, + VFIO_PCI_EXCLUDE_MMAP | + VFIO_PCI_EXCLUDE_READ | + VFIO_PCI_EXCLUDE_WRITE); + if (ret) + return ret; + /* * vfio_pci_core_disable() frees all dynamic regions on close, so register * them here per open rather than at bind. A failed first open never -- 2.25.1