[ndctl,v2,0/6] Add partitioning support for CXL memdevs

Message

Alison Schofield Jan. 12, 2022, 6:33 a.m. UTC

From: Alison Schofield <[e-mail]>

Users may want to view and change partition layouts of CXL memory
devices that support partitioning. Provide userspace access to
the device partitioning capabilities as defined in the CXL 2.0
specification.

The first 4 patches add accessors for all the information needed
to formulate a new partition layout. This info is accessible via
the libcxl API and a new option in the cxl list command:

    "partition_info":{
      "active_volatile_bytes":273535729664,
      "active_persistent_bytes":0,
      "next_volatile_bytes":268435456,
      "next_persistent_bytes":273267294208,
      "total_bytes":273535729664,
      "volatile_only_bytes":0,
      "persistent_only_bytes":0,
      "partition_alignment_bytes":268435456
    }

Patch 5 introduces the libcxl interfaces for the SET_PARTITION_INFO
mailbox command and Patch 6 adds the new CXL command: 

# cxl set-partition-info
 usage: cxl set-partition-info <mem0> [<mem1>..<memN>] [<options>]

    -v, --verbose         turn on debug
    -s, --volatile_size <n>
                          next volatile partition size in bytes

The CXL command does not offer the IMMEDIATE mode option defined
in the CXL 2.0 spec because the CXL kernel driver does not support
immediate mode yet. Since userspace could use the libcxl API to
send a SET_PARTITION_INFO mailbox command with immediate mode
selected, a kernel patch that rejects such requests is in review
for the CXL driver.

Tested with one memdev in a Simics environment. Still need to
expand that Simics config, use cxl_test, and add a unit test.

Repo: https://github.com/AlisonSchofield/ndctl/tree/as/partitions

Changes in v2:
- Rebase onto https://github.com/pmem/ndctl.git djbw/meson.
- Clarify that capacities are reported in bytes. (Ira)
  This led to renaming accessors like *_capacity to  *_bytes and 
  a spattering of changes in the man pages and commit messages.
- Add missing cxl_cmd_unref() when creating json objects. (Ira)
- Change the cxl list option to: -I --partition (Dan) 
- Use OPT_STRING for the --volatile_size parameter (Dan, Vishal)
- Drop extra _get_ in accessor names. (Vishal)
- Add an accessor for the SET_PARTITION_INFO mbox cmd flag.
- Display usage_with_options if size parameter is missing.
- Drop the OPT64 define patch. Use OPT_STRING instead.

Alison Schofield (6):
  libcxl: add GET_PARTITION_INFO mailbox command and accessors
  libcxl: add accessors for capacity fields of the IDENTIFY command
  libcxl: return the partition alignment field in bytes
  cxl: add memdev partition information to cxl-list
  libcxl: add interfaces for SET_PARTITION_INFO mailbox command
  cxl: add command set-partition-info

 Documentation/cxl/cxl-list.txt               |  23 ++++
 Documentation/cxl/cxl-set-partition-info.txt |  27 ++++
 Documentation/cxl/partition-description.txt  |  15 +++
 Documentation/cxl/partition-options.txt      |  20 +++
 cxl/builtin.h                                |   1 +
 cxl/cxl.c                                    |   1 +
 cxl/json.c                                   | 114 +++++++++++++++++
 cxl/lib/libcxl.c                             | 124 ++++++++++++++++++-
 cxl/lib/libcxl.sym                           |  15 ++-
 cxl/lib/private.h                            |  18 +++
 cxl/libcxl.h                                 |  15 ++-
 cxl/list.c                                   |   5 +
 cxl/memdev.c                                 | 101 +++++++++++++++
 util/json.h                                  |   1 +
 util/size.h                                  |   1 +
 15 files changed, 477 insertions(+), 4 deletions(-)
 create mode 100644 Documentation/cxl/cxl-set-partition-info.txt
 create mode 100644 Documentation/cxl/partition-description.txt
 create mode 100644 Documentation/cxl/partition-options.txt


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