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Thu, 9 Apr 2026 12:47:07 -0700 From: Nicolin Chen To: , , CC: , , , , , , , , , , Subject: [PATCH rc v1 0/4] iommu/arm-smmu-v3: Fix device crash on kdump kernel Date: Thu, 9 Apr 2026 12:46:49 -0700 Message-ID: X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ5PEPF00000203:EE_|CH3PR12MB8233:EE_ X-MS-Office365-Filtering-Correlation-Id: ef21bf16-a864-4c41-f02c-08de9670d3bc X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|36860700016|376014|82310400026|1800799024|13003099007|18002099003|56012099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.117.160;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge1.nvidia.com;CAT:NONE;SFS:(13230040)(7416014)(36860700016)(376014)(82310400026)(1800799024)(13003099007)(18002099003)(56012099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: ydUKGYi7z52fcyrSN55qnLcymtFiFrOUZ1yD4TPVXA/t2ElfX1yKgu4aEQI6DcKA3TD8/G1wpl2yG93Nx8h+z1uSAozOHJ7B+q76lOrrwKBge2fBh9M5eqoF0+jwWIGD292nu/LlyYRtBSkv/fy18eG7H/C8qRNd1bmT4CippqmcdGZ2qVI3ZCtPfzs+zjCdJUzfCE3bg01qbjJBJVkpM4gRcD909HCCAhh5UhCvSOhYhsvh2ZF7lnut1+A1m0HTePw/0JqfNpAinCXL61HdhYgkIf2Vwou22/eKx6xepnuPF0RVmju/hspiZvgxJ7dWvI3SdIRLscJlL82YEtY8FMAZtgOoaxYN6gdLHXDsZYenf2VQWaZittbvNPpIp7WQewTghOxOv3gsZeJWj22ig51ZuLYUR4Ly3pEge1x5YJdPqJObvsVwDp1XOuldlBXI X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Apr 2026 19:47:26.5806 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: ef21bf16-a864-4c41-f02c-08de9670d3bc X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: SJ5PEPF00000203.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB8233 When transitioning to a kdump kernel, the primary kernel might have crashed while endpoint devices were actively bus-mastering DMA. Currently, the SMMU driver aggressively resets the hardware during probe by clearing CR0_SMMUEN and setting the Global Bypass Attribute (GBPA) to ABORT. In a kdump scenario, this aggressive reset is highly destructive: a) If GBPA is set to ABORT, in-flight DMA will be aborted, generating fatal PCIe AER or SErrors that may panic the kdump kernel b) If GBPA is set to BYPASS, in-flight DMA targeting some IOVAs will bypass the SMMU and corrupt the physical memory at those 1:1 mapped IOVAs. To safely absorb in-flight DMA, the kdump kernel must leave SMMUEN=1 intact and avoid modifying STRTAB_BASE. This allows HW to continue translating in- flight DMA using the crashed kernel's page tables until the endpoint device drivers probe and quiesce their respective hardware. However, the ARM SMMUv3 architecture specification states that updating the SMMU_STRTAB_BASE register while SMMUEN == 1 is UNPREDICTABLE or ignored. This leaves a kdump kernel no choice but to adopt the stream table from the crashed kernel. In this series: - Introduce an ARM_SMMU_OPT_KDUMP - Skip SMMUEN and STRTAB_BASE resets in arm_smmu_device_reset() - Map the crashed kernel's stream tables into the kdump kernel [*] - Defer any default domain attachment to retain STEs until device drivers explicitly request it. [*] This is implemented via memremap, which only works on a coherent SMMU. Note that the entire series requires Jason's work that was merged in v6.12: 85196f5 ("iommu/arm-smmu-v3: Reorganize struct arm_smmu_strtab_cfg"). I have a backported version that is verified with a v6.8 kernel. I can send if we see a strong need after this version is accepted. This is on Github: https://github.com/nicolinc/iommufd/commits/smmuv3_kdump-v1 Nicolin Chen (4): iommu/arm-smmu-v3: Add arm_smmu_adopt_strtab() for kdump iommu/arm-smmu-v3: Implement is_attach_deferred() for kdump iommu/arm-smmu-v3: Retain SMMUEN during kdump device reset iommu/arm-smmu-v3: Detect ARM_SMMU_OPT_KDUMP in arm_smmu_device_hw_probe() drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 1 + drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 176 +++++++++++++++++++- 2 files changed, 174 insertions(+), 3 deletions(-) -- 2.43.0