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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?HWQur8mpGTaYRNuNeZsm3vyk46/bInYJ+ffGoVJaDjysxWH9jATxbI7g/NJp?= =?us-ascii?Q?j4bIhmPPkQ2JtGADXRQV2m/5YeMDXEypk+lMHQsm/3nD36ibhqBYrRYLvuHw?= =?us-ascii?Q?kN+fBctlHHkNMO1OIOVcnsuhsMKEqfleZKtwUB3qu3tlAkeFgIM4Mo7ze0k3?= =?us-ascii?Q?r3QCX7K8pkNMcczxAg15D5XfXmNRFmI+Bga3v9VOgZwGrtadr9hRPGgLsKRv?= =?us-ascii?Q?e99plptfR+iUA4uYWV8g1vA7ZXhA+qDeNKHmFE/HAxhrWqcZfAxm2S0wNp82?= =?us-ascii?Q?Fg1RoNnLFsKU74vProuHCPXYt7fyBfcLk/Ce7RVGwoo5MWGR1vSfdwOiRYIJ?= =?us-ascii?Q?LduHgZDAVnlq50Q1ZAursvZmPeYspNIFS3O/xk+MBAfsKE1MaMjYM1vxZf/l?= =?us-ascii?Q?Qb9mOsKxLLVDnUSHLMtyuFFzGpxE+wPB7xmava3v2v8V0lBdgJ677eFnVkAY?= =?us-ascii?Q?1CS0UixwgI0PWKqT8SsL53dR9LkejaFBpKkO+RCjA+J2NH7lRKpEgGuiHMXW?= =?us-ascii?Q?Tf3OvgBuIgG75PQl6wdJZiNttpRZ2n1VCdqqmOztOmXNZdwRE30LGk/8T/0Q?= =?us-ascii?Q?FSAGt77Z2KMLsMlDadk+Om5u3rZyzypvLdoh94itY5LBRLix/HByWc6W6y6O?= =?us-ascii?Q?5FaYAM0FMvh5DZiOHARdL+/8vbOx8+JHD+XMHSe/HhehLvmVhBOJqwydlBXK?= =?us-ascii?Q?f7aXlNRwAVfWvI1vaQCgNPqhXe6zgbMn+J6JmLgVFMtnNN+nU3xqRVPhyuBl?= =?us-ascii?Q?Ugu1iV1/dC111y51hcCOC0MYPr82Vy68ZA+WDGkJnKGibk6qwUFxf71uIlOt?= =?us-ascii?Q?oxA8/Z3QajusdvUODnl0M5djFcJ3FzCLTsnUKWztsERYjoamPmsYHMwbBtph?= =?us-ascii?Q?Ixef/0DLHT0rzZlSh6pXEJC4UQeJFJCoGgPL8fNADKGwOufF0gmz3CZWCvQs?= =?us-ascii?Q?HGCObdNCffnzG0Ks1g1t5M685jkI78sXYq8R87ViQo5++aKj2sY0XbtGCEqK?= =?us-ascii?Q?SPupGWtzb4wUQJo8Lup3Yzv7pKeK8EvnaIJPl58140iWYuP+jAOo0ULq5uxJ?= =?us-ascii?Q?UgiBKKRir6XvPJ9UdVfKXERQeH6BwZJT2Av+Wn6vdEYLxvbtPvjMRXyOh/8o?= =?us-ascii?Q?onG2d9krmjzv7p0wMihFxRs89UXuiZMhZU5DLQdudzPU6u2+ntuqrsZ0FWlA?= =?us-ascii?Q?JOVjD88Y7NOJT3RPsKlzWQyJFJBFp6Wh9IgPtbR+FvcvLQNlIKBU/KkCYrK1?= =?us-ascii?Q?LKxz1/IwpkjzqQElpWsDMq9r1bKEckDQ7Rj22myJHM38udnEzokjTYbVRbXq?= =?us-ascii?Q?3Sz7g7A7KvyvwuMvIkhWNirYVgCuQC4SSkarDQwgUy31aTSXX36lXiKDevFV?= =?us-ascii?Q?J8KqxbyVaSdgqSoeHquuM0LzYSHxTERLQGiV2+MLyRbdrE98O0LMu5AENqa4?= =?us-ascii?Q?cSQctH9nbO/yriUhVkL+CYItpmjZra/3O3gnhGHI8TDeUn8QQ9GlGciJKCqc?= =?us-ascii?Q?H0ZuavoNGY0CcK4qseEJl+iEG5ocIU03mCgBuww9h6KL5CUluH0Ca8DF33ws?= =?us-ascii?Q?dwpV7A9eL2zz4QGltYM=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: dc728ff3-2ffc-43c7-2ace-08de25f101a4 X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB3613.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 17 Nov 2025 15:50:17.9569 (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: DLi8JcM86Lz9a7WNfYP5qnh61YN4kTSZfg2UqiVR3TPqVnFzBqB2ixQ6Q2UEfbtK X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR12MB7848 On Thu, Nov 13, 2025 at 11:37:12AM -0700, Alex Williamson wrote: > > The latest series for interconnect negotation to exchange a phys_addr is: > > https://lore.kernel.org/r/20251027044712.1676175-1-vivek.kasireddy@intel.com > > If this is in development, why are we pursuing a vfio specific > temporary "private interconnect" here rather than building on that > work? What are the gaps/barriers/timeline? I broadly don't expect to see an agreement on the above for probably half a year, and I see no reason to hold this up for it. Many people are asking for this P2P support to be completed in iommufd. Further, I think the above will be easier to work on when we have this merged as an example that can consume it in a different way. Right now it is too theoretical, IMHO. > I don't see any uAPI changes here, is there any visibility to userspace > whether IOMMUFD supports this feature or is it simply a try and fail > approach? So far we haven't done discoverably things beyond try and fail. I'd be happy if the userspace folks doing libvirt or whatever came with some requests/patches for discoverability. It is not just this feature, but things like nesting and IOMMU driver support and so on. > The latter makes it difficult for management tools to select > whether to choose a VM configuration based on IOMMUFD or legacy vfio if > p2p DMA is a requirement. Thanks, In alot of cases it isn't really a choice as you need iommufd to do an accelerated vIOMMU. But yes, it would be nice to eventually automatically use iommufd whenever possible. Thanks, Jason