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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?iB+vBr+RP9FVCrqa7ICAME8NCb1w38JWnrLkyV4TYPUGbSOES1cN4ztX3hS+?= =?us-ascii?Q?pHG54ghGl/ic3nuJBU0mkSHFlxcXqusSo6ZjDnuruwGnY5XYcWee0bmP3Mea?= =?us-ascii?Q?4Omb3QVr5rJ3P2Jn84hrcgX5M0JCq098s0db8+OcWFsrUPBs49Gw1JnXD3AM?= =?us-ascii?Q?wq29CcyKA1k+D9SPTMP9Euc1j8eITQjzVurH3KYI51ObpxnpdYSYHj0QL9lj?= =?us-ascii?Q?uw73bwl16NQAAVqDtu9AGCt+STPOcJ9Zt1XDnAeK2D6w/8B0h5kRG8nMcFEK?= =?us-ascii?Q?bg4tGCTOfSYsVsc0QWkIGpAXjR2sxribxg5JS/WwHIwJt5+gTzwujJzxwE71?= =?us-ascii?Q?c1gk3eQaSGoWaiTgNhEi1UHivZtR0SCMk8+r6jbcaoEcgx4wcOdUPhuXgaQW?= =?us-ascii?Q?NhxdKwOZBN7PASZHbavqkipjov6rQ5e6ThL4NH5xmskq+uwKVrkuOot7VkP9?= =?us-ascii?Q?RYELBcKKwUg0BMYBlXEdDvrjIGD0HW4y4LFUIYPnj32Kf5X2DLAMzFDQxwlG?= =?us-ascii?Q?+T5SHnuqOBK8092Pnt42/OO7Q8/HarWbRd/gGGM9nmq4trVBYUFPGkv/KfiH?= =?us-ascii?Q?puaOKFauKrVgzridFxkXd4hBF0jktUJbdQiYd54iZHKFr6zXVOxRA9G1FQ3U?= =?us-ascii?Q?NEC/gJwqHoXLdZ7SVcjFYcFHGoO5boJy852BxYNzWYgu+ODGXEj6O0wv5OTy?= =?us-ascii?Q?bibnf9OB7LxtuUfd55TVtpZDrQ1UZ9NWfnBdpvBS9ROorLAzb4nFAdv5giJW?= =?us-ascii?Q?EHOXHhcirbRQjzmqvEPH/wVv6e/jLysMXyo4HahC+L3fgqnA2V/jg1BTe4nN?= =?us-ascii?Q?SfMuMj5OUIAEtiOZTBPxZeyppjS5Uo1Z5iF89ZMyGH1oFOhmBEeZJkkXJIRr?= =?us-ascii?Q?CbmF7xle/LZ6tdLOrZPfKPgfFyKHDC8T6SzPXLww2H3IR4CKb3d9rQcC9189?= =?us-ascii?Q?zqwePIRJHmmcTRxhv9/d9zcZm25c6FmoxHJw8ste37rwLjfSaWGOKakXyldC?= =?us-ascii?Q?gfMJyT+714Kyks5wbGCuQ1yqGUXgidboKLFin/e43ui+tVCZ3a9mTwBJ8H9r?= =?us-ascii?Q?MKE+wpi1fOKzQZ/pmXmQQhhRKAhLdOBMlCIDtNejQZGlOM5kfId4c+QCmLGm?= =?us-ascii?Q?Whhep/grvVWRsYL9Y7rLfmsCEny63Lf+Rem5wLNY5bfntk3ZLcDVwaRcisOb?= =?us-ascii?Q?8ecmMq5X5oIuEBOW5p7QwHVjM8TWwLh9PbCd5lf/+E3KNrN6jzq7KOv0soU2?= =?us-ascii?Q?PZKDVPyEwTjj/z4f/4GgC3WlcweYb9uqCzkupiWzFY0I/E2DMU5P5gspnHdg?= =?us-ascii?Q?SlfY4MWZ9mo+a9DhWYb5ulmNcoy2FYGlm9iLAW4t3ooDgg/bEZeKbjOVU5zz?= =?us-ascii?Q?1AwtE+5IVrFdMRGmfMw8AX4jGTAhTc79BPd2/zt8fkF/Rk9+2kxP6dKq2HJ0?= =?us-ascii?Q?rtcBckAs6AJ+2Rlflocko44Xp3mQDTG0Tf2xQQ+MpVGG6xXrjddgwu+RbfTP?= =?us-ascii?Q?3CeG2fTd0Dq3bFnBgQ8MbSPkvByV4inr1VgUKDDpjzWF42AxcIzcZoLgzM01?= =?us-ascii?Q?omMNSgbMnpKncmnYwZnDjSRR9EJi6ARkPXpeKwGEpR7V0Prvl4GuaqcogTX0?= =?us-ascii?Q?iGl0Y1O/6kW8N8XbhNMFiX2moEXFAp9CthN9iLeKwW+GMvWaXnkQKURva7az?= =?us-ascii?Q?2bfwqwSB10WyG8FVdxaouG8sCAeWAurOrGhcwkQycwn0y4bs?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: f653df9a-ff90-460d-f838-08df14c077ff X-MS-Exchange-CrossTenant-AuthSource: CHBPR12MB731189.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 17 Sep 2026 13:34:59.0345 (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: 24yjeOr//gTQuKVNlogv/eLm0nsM40iZB2d8+m8vFzkt30iJOmV7lwjIilcGHxo1 X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN7PR12MB8769 On Thu, Sep 17, 2026 at 04:18:16PM +0530, sonang patel wrote: > On Wed, 9 Sep 2026 20:32:49 -0700, Nicolin Chen wrote: > > + * @tdisp_t1: device uses its confidential IOMMU's T=1 stream. A zero value > > + * means T=0, where the T=1 stream remains blocked while the core > > + * owns required DMA operations such as ATS. > > What happens when the TDI transitions to ERROR, and how does this bit > signify it? > A TDI can drop to ERROR asynchronously, and at that point the device is > outside the trust boundary again. The bit reflects how the kernel expects the device to do DMA. It does not change when the TDISP state changes. A device that falls to error can no longer do T=1 DMA, the device is expected to halt that internally. It must not start doing T=0 DMA in error either or it will corrupt random shared memory since T=0/T=1 are different IOVA spaces on ARM and Intel. To recover out of error the userpace would have to cycle it through err/unlocked/locked/run and tell the kernel driver to start it up again. During that time the device must not do any T=0 DMA because nothing has been mapped to it in the T=0 regime. >From the driver perspecitve the device simply stops doing DMA for a while and when it comes back in RUN it is able to do DMA again. It is sort of like existing RAS flows where a device crashes. Jason