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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?BxiW19NR+PXHCfWRJORY2dlgB8f0HeQI7WkjRhJV5AgnDSsbFobN4ZlH4tU+?= =?us-ascii?Q?Csb13aFhRNwyVanlPqk5ka4cky/gFNfp+Kynn2bmUnmBzqww4R2uHLxL9wn4?= =?us-ascii?Q?ynRIDmqgiDB+J4YTuy6DndyRfVxVfkfZjKjA+kHgIyFwBMBJU0rU73IGJx/+?= =?us-ascii?Q?WG/KjFx9oBFN7WP0ZxWbE1DKBI1JG8Lu7BI2mKkUAGc0tdpFQzD1/hHRNZkP?= =?us-ascii?Q?d25BKSnTfXqfCss0qT6ieufnGnWNLQd2tRCbZJxCygup8o/X7mrMFwehEBjs?= =?us-ascii?Q?dtSWRQMbWRGyAj8yRG5vJxirECnBreREypytZmbGK3Bt1Ayne9aU23myZwrN?= =?us-ascii?Q?OAPiJ1rCLf/SD6HGBq/ZRDPmVxPGJnH0Hw4kq9xOcdvOBKUabxxdJMiOJ6IO?= =?us-ascii?Q?X38eEe5BKz8yIlS7mYT/HB7IOPcmKwnNJ8AtHljQZJMJlQlMQfICVFZFyclU?= =?us-ascii?Q?owS9vRTztUjvfK9S0AEd1me9E6rXzVZB3RKTodiRGJU8LVENxq7hNGiW3DKX?= =?us-ascii?Q?iBHpeTee82wFU7P77vGb0SatKpZtTOTC0jd8EXCXjAz96AHioCob+fbG7V+y?= =?us-ascii?Q?YBKHyhorkcOe6iUn21yKcxUZLg8x0uaavGI27Uf0Zf7doC1MvaZZUceGz+Gu?= =?us-ascii?Q?zIdTPhnckAn8zSCgH+ZJ7Ta6m2ODUJ9qmZEIjAQPIwBlQVpH5dLniaY4HqPO?= =?us-ascii?Q?DwRwrxelNWsAGQw0WY9DcQx6N6xiZofTryIOyD3H/HcFM0wGEzTSXRikelOD?= =?us-ascii?Q?QK0J6UpbgcLgMmEkNElTPXQmIAg+nX7K/MUD0LwvjnKQpak65E2DunR/pyo6?= =?us-ascii?Q?DmFO3/Pq08YTK09Bx2r5geWuoE4anIh4RM0chzdIFImjhm8YVI9GsQJSd8hf?= =?us-ascii?Q?eA9gvnUOOIwZyA3PO/OBQAJdV/sakSmn2ytP6upvzevwWdGNaifgAP9FjZck?= =?us-ascii?Q?dmQnE3czPz6DHYgUnvw0D9+fo1kMHry53WQtVJQreuFx3zPyKPWlZVtdYoWv?= =?us-ascii?Q?rwqkR0Epp5ZVM7G0L+RZBuMLxAQ9a5gx+oa2nGhvkEuqItNYiwxKrfViLFsh?= =?us-ascii?Q?RxhKj9fhhDrTrfSZZPTS/Dbn01Vv/yskXc73yEFFXCi8fXnCttfRcThb26lQ?= =?us-ascii?Q?+/JRvfGRmfz8gj71vVZpbE9yki67Ej0Z5cbB0KusBqo98BuB0d9BTaUPbai5?= =?us-ascii?Q?JwufobIh+9etYQnipWVWStzIg6B2obuQD/76msaC1ccgFQcsfLInhpbaAu95?= =?us-ascii?Q?fO0K5oadpQgh6ScwKDKUdYhoTCEoFfbZ8ZAGudAh8v4VVshlosvXHKtUW6se?= =?us-ascii?Q?iPFzgihQW7XI9I9/U0dNvGl0ZGd2EGmx2ZeGNQB5duwTmYnKy6whx3WFtX/f?= =?us-ascii?Q?3W3j02s/5WRV/O4JwvMiXIIqcXFOYR6EvBZlKtXtJ9wEru/K5GdbIPec1m++?= =?us-ascii?Q?bbX4LnY7am9UOiDGtBTCFglbRkN4yPj4XSMU2NvYWkkqazIW3OX7i7AmM4r3?= =?us-ascii?Q?mALQtnujPsziUYhMPhoh0Z7DnxXziQADNwyTKzA8MP8DyfcX4omsV+f1vZT5?= =?us-ascii?Q?LgxLk7MBGRyd3v+6GTGhQs1VMkCnTwVnPeiZUkNlTf53GZ36Ty4sZeDu7EV2?= =?us-ascii?Q?k8JIh2wmnemyz+chPTXd3qb74ZURf6LMaE+9QjpZnMxvP78CO14T+3Pr+rYc?= =?us-ascii?Q?NlqhDAxLLdLqgNHhIDlve2gq4wZqFl7/Ngw0ONY/s2EKl9Xv0kTvKTh51EAN?= =?us-ascii?Q?D3nDgO0UXw=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: fe923d0f-e0fb-4261-b4ba-08de62746f65 X-MS-Exchange-CrossTenant-AuthSource: LV8PR12MB9620.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 Feb 2026 16:02:15.9557 (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: ZlRi36ExSPcG9pwcuzKjQFTGN9BvK2jyGRt+JDm8sHGumIxLnHsEvD+om9CUV0cx X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ1PR12MB6364 On Mon, Feb 02, 2026 at 07:33:34PM +0800, Wei Wang wrote: > The ACS Enhanced Capability introduces several new access controls to > improve device isolation. These new controls are particularly important > for device passthrough in virtualization scenarios. > > For example, a DMA transaction from a device may target a guest physical > address that lies within the memory aperture of the switch's upstream > port, but not within any memory aperture or BAR space of a downstream > port. In such cases, the switch would generate an Unsupported Request (UR) > response to the device, which is undesirable. Enabling Unclaimed Request > Redirect Control ensures that these DMA requests are forwarded upstream > instead of being rejected. > > The ACS DSP and USP Memory Target Access Control and ACS I/O Request > Blocking features similarly enhance device isolation. Device grouping in > Linux assumes that devices are properly isolated. Therefore, enable these > controls by default if PCI_ACS_ECAP is supported by the hardware. As with > other basic ACS access controls, these new controls can be configured via > the config_acs= boot parameter. > > Signed-off-by: Wei Wang > --- > .../admin-guide/kernel-parameters.txt | 23 +++++++++++++------ > drivers/pci/pci.c | 13 ++++++++++- > include/uapi/linux/pci_regs.h | 7 ++++++ > 3 files changed, 35 insertions(+), 8 deletions(-) Reviewed-by: Jason Gunthorpe Jason