[PATCH v4 0/8] cxl: support CXL memory RAS features

[<shiju.jose@huawei.com>]

From: Shiju Jose <shiju.jose@huawei.com>

Support for CXL memory EDAC features: patrol scrub, ECS, soft-PPR and
memory sparing.

Detailed history of the complete EDAC series with CXL EDAC patches[1].

The code is based on [2] v6.15-rc4.

1. https://lore.kernel.org/linux-cxl/20250212143654.1893-1-shiju.jose@huawei.com/
2. https://github.com/torvalds/linux.git

Userspace code for CXL memory repair features [3] and
sample boot-script for CXL memory repair [4].

[3]: https://lore.kernel.org/lkml/20250207143028.1865-1-shiju.jose@huawei.com/
[4]: https://lore.kernel.org/lkml/20250207143028.1865-5-shiju.jose@huawei.com/

Changes
=======
v3 -> v4:
1. Feedback from Dave Jiang on v3,
1.1. Changes for comments in EDAC scrub documentation for CXL use cases.
     https://lore.kernel.org/all/2df68c68-f1a8-4327-abc9-d265326c133d@intel.com/
1.2. Changes for comments in CXL memory sparing control feature.
     https://lore.kernel.org/all/4ee3323c-fb27-4fbe-b032-78fd54bc21a0@intel.com/
      
v2 -> v3:
1. Feedback from Dan Williams on v2,
   https://lore.kernel.org/linux-mm/20250320180450.539-1-shiju.jose@huawei.com/
  - Modified get_support_feature_info() in fwctl series generic to use in
    cxl/fxctl and cxl/edac and replace cxl_get_feature_entry() in the CXL edac
    series.
  - Add usecase note for CXL ECS in Documentation/edac/scrub.rst.
  - Add info message when device scrub rate set by a region overwritten with a
    local device scrub rate or another region's scrub rate.
  - Replace 'ps' with patrol_scrub in the patrol scrub feature.
  - Replaced usage of intermediate objects struct cxl_memdev_ps_params and
    enum cxl_scrub_param etc for patrol scrub and did same for ECS.
  - Rename CXL_MEMDEV_PS_* macros.
  - Rename scrub_cycle_hrs-> scrub_cycle_hours
  - Add if (!cxl_dev_name)
	return -ENOMEM;  to devm_cxl_memdev_edac_register()
  - Add  devm_cxl_region_edac_register(cxlr) for CXL_PARTMODE_PMEM case.
  - Add separate configurations for CXL scrub, ECS and memory repair
    CXL_EDAC_SCRUB, CXL_EDAC_ECS and CXL_EDAC_MEM_REPAIR.
  - Add 
       if (!capable(CAP_SYS_RAWIO))
             return -EPERM; for set attributes callbacks for CXL scrub, ECS and
    memory repair.  	       
  - In patch "cxl/mbox: Add support for PERFORM_MAINTENANCE mailbox command"
    * cxl_do_maintenance() -> cxl_perform_maintenance() and moved to cxl/core/edac.c 
    * kmalloc() -> kvzalloc()
  - In patch, "cxl: Support for finding memory operation attributes from the current boot"  
    * Moved code from drivers/cxl/core/ras.c to drivers/cxl/core/edac.c
    * Add few logics to releasing the cache to give safety with respect to error storms and burning
    * unlimited memory. 
    * Add estimated memory overhead expense of this feature documented in the Kconfig.
    * Unified various names such as attr, param, attrbs throughout the patches.
    * Moved > struct xarray rec_gen_media and struct xarray rec_dram; out of struct cxl_memdev
      to CXL edac object, but there is required a pointer to this object in struct cxl_memdev
      because the error records are reported and thus stored in the cxl_memdev context not
      in the CXL EDAC context.
      
2. Feedback from Borislav on v2,
  - In include/linux/edac.h 
    Replace EDAC_PPR -> EDAC_REPAIR_PPR
            EDAC_CACHELINE_SPARING -> EDAC_REPAIR_CACHELINE_SPARING etc.

v1 -> v2:
1. Feedback from Dan Williams on v1,
   https://lore.kernel.org/linux-mm/20250307091137.00006a0a@huawei.com/T/
  - Fixed lock issues in region scrubbing, added local cxl_acquire()
    and cxl_unlock.
  - Replaced CXL examples using cat and echo from EDAC .rst docs
    with short description and ref to ABI docs. Also corrections
    in existing descriptions as suggested by Dan.
  - Add policy description for the scrub control feature.
    However this may require inputs from CXL experts.
  - Replaced CONFIG_CXL_RAS_FEATURES with CONFIG_CXL_EDAC_MEM_FEATURES.
  - Few changes to depends part of CONFIG_CXL_EDAC_MEM_FEATURES.
  - Rename drivers/cxl/core/memfeatures.c as drivers/cxl/core/edac.c
  - snprintf() -> kasprintf() in few places.

2. Feedback from Alison on v1,
  - In cxl_get_feature_entry()(patch 1), return NULL on failures and
    reintroduced checks in cxl_get_feature_entry().
  - Changed logic in for loop in region based scrubbing code.
  - Replace cxl_are_decoders_committed() to cxl_is_memdev_memory_online()
    and add as a local function to drivers/cxl/core/edac.c
  - Changed few multiline comments to single line comments.
  - Removed unnecessary comments from the code.
  - Reduced line length of few macros in ECS and memory repair code.
  - In new files, changed "GPL-2.0-or-later" -> "GPL-2.0-only".
  - Ran clang-format for new files and updated.                                                                                                                                          
3. Changes for feedbacks from Jonathan on v1.
  - Changed few multiline comments to single line comments.

Shiju Jose (8):
  EDAC: Update documentation for the CXL memory patrol scrub control
    feature
  cxl: Update prototype of function get_support_feature_info()
  cxl/edac: Add CXL memory device patrol scrub control feature
  cxl/edac: Add CXL memory device ECS control feature
  cxl/edac: Add support for PERFORM_MAINTENANCE command
  cxl/edac: Support for finding memory operation attributes from the
    current boot
  cxl/edac: Add CXL memory device memory sparing control feature
  cxl/edac: Add CXL memory device soft PPR control feature

 Documentation/edac/memory_repair.rst |   31 +
 Documentation/edac/scrub.rst         |   76 +
 drivers/cxl/Kconfig                  |   71 +
 drivers/cxl/core/Makefile            |    1 +
 drivers/cxl/core/core.h              |    2 +
 drivers/cxl/core/edac.c              | 2082 ++++++++++++++++++++++++++
 drivers/cxl/core/features.c          |   17 +-
 drivers/cxl/core/mbox.c              |   11 +-
 drivers/cxl/core/memdev.c            |    1 +
 drivers/cxl/core/region.c            |   10 +
 drivers/cxl/cxl.h                    |   10 +
 drivers/cxl/cxlmem.h                 |   36 +
 drivers/cxl/mem.c                    |    4 +
 drivers/edac/mem_repair.c            |    9 +
 include/linux/edac.h                 |    7 +
 15 files changed, 2356 insertions(+), 12 deletions(-)
 create mode 100644 drivers/cxl/core/edac.c

-- 
2.43.0