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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?