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Thu, 4 Dec 2025 04:22:25 +0000 Date: Wed, 3 Dec 2025 20:22:17 -0800 From: Alison Schofield To: Robert Richter CC: Vishal Verma , Ira Weiny , Dan Williams , Jonathan Cameron , Dave Jiang , "Davidlohr Bueso" , , , Gregory Price , "Fabio M. 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?pPpO0ZeaeP8EDKJTPWk6r9DW3WdA3D/t+GPTUCRNVeyj74tgVUhYJzQ94M4N?= =?us-ascii?Q?ADO+d43a/iefhUXR6abG6NnNx15xfJokUfdLoXC+KwDImzJYX8AUccvyf5XM?= =?us-ascii?Q?65jO+ZcR4Iods4vrcaAjEzPcGAWNnqgdBiQ1OrhbaajXsvTG9SkElHQQ1X2g?= =?us-ascii?Q?KTII9T0WK56fdvome19PkfDjPREHytpD6G2mxE1zJWpO26JZBkdSKwzO9FBJ?= =?us-ascii?Q?BAs1fDV6djm0BOv8JNeW8coikNBjwMryAl7MUsvd0b4PqTenU9MNd2kcJMaU?= =?us-ascii?Q?m+7IkxEspeC5GdD4mMZKU/WPceboDoCQzmT1LeZfUiA4f7AUB2I7D9deWllY?= =?us-ascii?Q?QQYNOVa1SHE8bj6m3210p++vWjuAKfrlpTdjzrHP4364NQ6ifqTgRzmEAC5Q?= =?us-ascii?Q?6bVcrRowvdozEPXSSN6dgm2mmW5gJ0W5X9P7MD1pBLGNpt84Fm8Y7vPsB/1s?= =?us-ascii?Q?xrOimyRYuih99RMVm6D7n+aifWlpKffFKZ4ar+a1af4kjdhidIQsRFTzaVe+?= =?us-ascii?Q?WgWV86bVLbhjSxmI8gkf12XlzWlTf5xHmDIO11/CSrLGnOl5qYY2zZc0FhtM?= =?us-ascii?Q?vojwIJ+132eTmgz9ykQkjhkC/aSwUUjfeM3EIuGLgE4uUvdo4FzTcDcvGMfJ?= =?us-ascii?Q?/GqzjbM6xW9UU58kJC/aNidQc72SIqX5oBisK5kOKrnhth3v+5rScDL2pomY?= =?us-ascii?Q?0w/ihEvl/ujYGz6gL9LLY3fA3zLpH/8hp/eb/3KEIvHbuIc05wdAi/uS5DZt?= =?us-ascii?Q?zwF6Na2zBsEJdMvDIw+ddyQl5eqpFmmCjnxyS6Mwm7aIcTgKZEBGprK9M5wr?= =?us-ascii?Q?vBv8HmcKi+8fvzBAtqMXJ3gyFlbvKBoVrwdweftZL3vX5PJSBFE0APeW6nrN?= =?us-ascii?Q?zzBm97gdikGlOOkl5CzWvjBPlOwS+uTXzdwpdayeeHSByXiczrtq/1yngT/w?= =?us-ascii?Q?j6Nu4kHeED1ulgAPAy7Vb+ACChK881bavKFSG/JNVhqTUyXz+u0ZXKYJP2xR?= =?us-ascii?Q?lwyO7coRvLmGgiNdf9STOfwEqGmO816g/Gp1MR+576lv9CQSLz0tcTPphZlc?= =?us-ascii?Q?yj+mJS+f/JRes1NvGxXrXEWr19v674+gHJGi7pnhJGHyssrWCoyQZrQ+k8RL?= =?us-ascii?Q?DWR+is6vedj3wxs3QSE4PiXORX8UfQRZ1bvlsGgmpExE9KwCN1Dcmd92ex5r?= =?us-ascii?Q?OMw9cBagkLDmbJctebKuvMtTePThZHsq7kU4mBkfzEK/FP/z/eErJg2HVffm?= =?us-ascii?Q?e1spFgkvuhdXkE1kUalePgqqS5X9Hv74CdJzSm6cZ71fOI7Scgy/qtS3G01s?= =?us-ascii?Q?4igNF+ivb4qG+5UfGrNGPngianp/VYukslE6FRDeO6Pow/V3vnqgJxgLyL+T?= =?us-ascii?Q?dLLBLbOs4vD69MY//tRHUw/BWjMqppkuSxnU5DbYxwcNLTF3j8BYzfE/BYuC?= =?us-ascii?Q?LVsuPp8OvU2qLyKOHcg7hGGRwT83p+YrSJpjSkQY99e3Uw/E4Xhrkncor4Ut?= =?us-ascii?Q?tU/Qojc9hV04XAQ/RXlTWOxkWtC+MN7iu11hoCVOxeNr+Z198CmoYN9MnQMJ?= =?us-ascii?Q?yH88686ho7+TzbjoPNFdxqhI9Gqph+jepzrH9i/rAa1fLQV5aR1bdn0EjHJo?= =?us-ascii?Q?rQ=3D=3D?= X-MS-Exchange-CrossTenant-Network-Message-Id: 5a0a5197-8c2d-4219-1b63-08de32ecba53 X-MS-Exchange-CrossTenant-AuthSource: DS4PPF0BAC23327.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Dec 2025 04:22:25.5737 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: iHCvfJOifEUTAkBWWsyyzoEIqrr2K/kc44n0zFyd2GI6eZ7hWWwIONy2A9czGLFrWm4iHIg0fgUxsODjFkLcZQIfLrXVxM4+ME0YBKR5PfU= X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH8PR11MB8108 X-OriginatorOrg: intel.com On Mon, Nov 17, 2025 at 03:58:40PM +0100, Robert Richter wrote: > On 14.11.25 12:01:29, Alison Schofield wrote: > > > Does this work 'as is', no changes required, to support DPA->SPA > > (used in CXL Events) or SPA->DPA (used in poison by region offset)? > > The PRM handler could be used for to-SPA translations, but it might > not fit well to other users such as profiling, tracing and error > handling. Those users are executing in a critical path from a > performance or stability point of view. Performing a firmware call > could cause problems here. Since the to-DPA translation is missing > too, a different approach to solve address translation might work > better, such as examining the region parameters. The kernel's address > translation library could possibly be extended and used too. That > needs to be figured out. Also, my main focus for the patches is region > enablement. I see a dpa-to-spa prm routine. I don't know enough about the cost of using it to say it's not worth using for CXl trace events that want to report a SPA (from a DPA). If we cannot trust what the address translation code will emit in this case, forcing it to ULLONG_MAX would be safest. -- Alison > > Thanks, > > -Robert