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De Francesco" , Terry Bowman , Joshua Hahn References: <20260110114705.681676-1-rrichter@amd.com> <125a0a77-b966-410c-b9e4-a7d81e462576@intel.com> Content-Language: en-US From: Dave Jiang In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2/4/26 5:58 AM, Robert Richter wrote: > Hi Dave, > > On 03.02.26 11:52:02, Dave Jiang wrote: >> >> >> On 1/10/26 4:46 AM, Robert Richter wrote: >>> This patch set adds support for address translation using ACPI PRM and >>> enables this for AMD Zen5 platforms. The current approach bases on v4 >>> and is in response to earlier attempts to implement CXL address >>> translation: >>> >>> * v1: [1] and the comments on it, esp. Dan's [2], >>> * v2: [3] and comments on [4], esp. Dave's [5], >>> * v3: [6] and comments on it, esp. Dave's [7], >>> * v4: [8]. >>> >>> This version addresses Alison's review comments to change the >>> implementation to disable HPA/SPA translation handler. There are a >>> view minor but no major changes otherwise. See the changelog for >>> details. Thank you all for your reviews and testing. >>> >>> Documentation of CXL Address Translation Support will be added to the >>> Kernel's "Compute Express Link: Linux Conventions". This patch >>> submission will be the base for a documentation patch that describes CXL >>> Address Translation support accordingly. >>> >>> The CXL driver currently does not implement address translation which >>> assumes the host physical addresses (HPA) and system physical >>> addresses (SPA) are equal. >>> >>> Systems with different HPA and SPA addresses need address translation. >>> If this is the case, the hardware addresses esp. used in the HDM >>> decoder configurations are different to the system's or parent port >>> address ranges. E.g. AMD Zen5 systems may be configured to use >>> 'Normalized addresses'. Then, CXL endpoints have their own physical >>> address base which is not the same as the SPA used by the CXL host >>> bridge. Thus, addresses need to be translated from the endpoint's to >>> its CXL host bridge's address range. >>> >>> To enable address translation, the endpoint's HPA range must be >>> translated to the CXL host bridge's address range. A callback is >>> introduced to translate a decoder's HPA to the CXL host bridge's >>> address range. The callback is then used to determine the region >>> parameters which includes the SPA translated address range of the >>> endpoint decoder and the interleaving configuration. This is stored in >>> struct cxl_region which allows an endpoint decoder to determine that >>> parameters based on its assigned region. >>> >>> Note that only auto-discovery of decoders is supported. Thus, decoders >>> are locked and cannot be configured manually. >>> >>> Finally, Zen5 address translation is enabled using ACPI PRMT. >>> >>> This series bases on v6.19-rc1. >> >> Applied to cxl/next. Including the conventions doc. >> 00bc604c96bb762f0f050460e25de2729edb1699 > > Thank you for applying the series, I noticed wrong authorship of > a0a135b410f57702ac6a463005c656f291eb7b90, could you fix that? Sorry about that. Not sure how it happened. Fixed now. cxl/next repushed. 63fbf275fa9f18f7020fb8acf54fa107e51d0f23 > > Thank you, > > -Robert