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 u+73EcBc 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early generation CXL platforms. > > So isn't the problem that CLFLUSH and friends take a linear address > rather than a physical address? I suppose we can use our 1:1 mapping in > this case, is all of CXL in the 1:1 map? Currently CXL on the unplug path does: arch_remove_memory() /* drop direct map */ cxl_region_invalidate_memregion() /* wbinvd_on_all_cpus() */ cxl_region_decode_reset() /* physically unmap memory */ ...and on the plug path: cxl_region_decode_commit() /* physically map memory */. cxl_region_invalidate_memregion() /* wbinvd_on_all_cpus() */ arch_add_memory() /* setup direct map */ Moving this to virtual address based flushing would need some callbacks from the memory_hotplug code to run flushes for memory spaces that are being physically reconfigured. ...unplug: arch_remove_memory() clwb_on_all_cpus_before_unmap() cxl_region_decode_reset() ...plug: cxl_region_decode_commit() arch_add_memory() clflushopt_on_all_cpus_before_use() However, this raises a question in my mind. Should not all memory hotplug drivers in the kernel be doing cache management when the physical contents of a memory range may have changed behind a CPUs back? Unless I am missing something it looks like the ACPI memory hotplug driver, for example, has never considered that an unplug/replug event may leave stale data in the CPU cache. I note drm_clflush_pages() is existing infrastructure and perhaps CXL should uplevel/unify on that common helper?