Introduction: ============= CXL Persistent Memory (Pmem) devices region, namespace and content must be persistent across system reboot. In order to achieve this persistency, it uses Label Storage Area (LSA) to store respective metadata. During system reboot, stored metadata in LSA is used to bring back the region, namespace and content of CXL device in its previous state. CXL specification provides Get_LSA (4102h) and Set_LSA (4103h) mailbox commands to access the LSA area. nvdimm driver is using same commands to get/set LSA data.
There are three types of LSA format and these are part of following specifications: - v1.1: https://pmem.io/documents/NVDIMM_Namespace_Spec.pdf - v1.2: https://uefi.org/sites/default/files/resources/UEFI_Spec_2_7.pdf - v2.1: https://computeexpresslink.org/wp-content/uploads/2024/02/CXL-2.0-Specification.pdf Basic differences between these LSA formats: - v1.1: Support Namespace persistency. Size of Namespace Label is 128 bytes - v1.2: Support Namespace persistency. Size of Namespace Label is 256 bytes - v2.1: Support Namespace and Region persistency. Size of Namespace and Region Label is 256 bytes. Linux nvdimm driver supports only v1.1 and v1.2 LSA format. CXL pmem device require support of LSA v2.1 format for region and namespace persistency. Initial support of LSA 2.1 was add in [1]. This patchset adds support of LSA 2.1 in nvdimm and cxl pmem driver. Patch 1: Introduce NDD_CXL_LABEL flag and Update cxl label index as per v2.1 Patch 2-4: Update namespace label as per v2.1 Patch 5-12: Introduce cxl region labels and modify existing change accordingly Patch 13: Refactor cxl pmem region auto assembly Patch 14-18: Save cxl region info in LSA and region recreation during reboot Patch 19: Segregate out cxl pmem region code from region.c to pmem_region.c Patch 20: Introduce cxl region addition/deletion attributes Testing: ======== In order to test this patchset, I also added the support of LSA v2.1 format in ndctl. ndctl changes are available at [2]. After review, I’ll push in ndctl repo for community review. 1. Used Qemu using following CXL topology M2="-object memory-backend-file,id=cxl-mem1,share=on,mem-path=$TMP_DIR/cxltest.raw,size=512M \ -object memory-backend-file,id=cxl-lsa1,share=on,mem-path=$TMP_DIR/lsa.raw,size=1M \ -object memory-backend-file,id=cxl-mem2,share=on,mem-path=$TMP_DIR/cxltest2.raw,size=512M \ -object memory-backend-file,id=cxl-lsa2,share=on,mem-path=$TMP_DIR/lsa2.raw,size=1M \ -device pxb-cxl,bus_nr=10,bus=pcie.0,id=cxl.1 \ -device cxl-rp,port=1,bus=cxl.1,id=root_port11,chassis=0,slot=1 \ -device cxl-type3,bus=root_port11,memdev=cxl-mem1,lsa=cxl-lsa1,id=cxl-pmem1,sn=1 \ -device cxl-rp,port=2,bus=cxl.1,id=root_port12,chassis=0,slot=2 \ -device cxl-type3,bus=root_port12,memdev=cxl-mem2,lsa=cxl-lsa2,id=cxl-pmem2,sn=2 \ -M cxl-fmw.0.targets.0=cxl.1,cxl-fmw.0.size=4G,cxl-fmw.0.interleave-granularity=8k" 2. Create cxl region on both devices cxl create-region -d decoder0.0 -m mem0 cxl create-region -d decoder0.0 -m mem1 root@QEMUCXL6060pmem:~# cxl list [ { "memdevs":[ { "memdev":"mem0", "pmem_size":536870912, "serial":2, "host":"0000:0c:00.0", "firmware_version":"BWFW VERSION 00" }, { "memdev":"mem1", "pmem_size":536870912, "serial":1, "host":"0000:0b:00.0", "firmware_version":"BWFW VERSION 00" } ] }, { "regions":[ { "region":"region0", "resource":45365592064, "size":536870912, "type":"pmem", "interleave_ways":1, "interleave_granularity":256, "decode_state":"commit", "qos_class_mismatch":true }, { "region":"region1", "resource":45902462976, "size":536870912, "type":"pmem", "interleave_ways":1, "interleave_granularity":256, "decode_state":"commit", "qos_class_mismatch":true } ] } ] 3. Re-Start Qemu and we could see cxl region persistency using "cxl list" 4. Create namespace for both regions root@QEMUCXL6060pmem:~# ndctl create-namespace --mode=fsdax --region=region0 --size=128M { "dev":"namespace0.0", "mode":"fsdax", "map":"dev", "size":"124.00 MiB (130.02 MB)", "uuid":"3f6dcdc5-d289-4b0c-ad16-82636c82bec1", "sector_size":512, "align":2097152, "blockdev":"pmem0" } root@QEMUCXL6060pmem:~# ndctl create-namespace --mode=fsdax --region=region1 --size=256M { "dev":"namespace1.0", "mode":"fsdax", "map":"dev", "size":"250.00 MiB (262.14 MB)", "uuid":"6b9083c9-cb1a-447b-894d-fdfd2f3dbed2", "sector_size":512, "align":2097152, "blockdev":"pmem1" } root@QEMUCXL6060pmem:~# time ndctl create-namespace --mode=fsdax --region=region0 --size=256M { "dev":"namespace0.1", "mode":"fsdax", "map":"dev", "size":"250.00 MiB (262.14 MB)", "uuid":"c2071802-8c24-4f9c-a6c1-f6bb6589e561", "sector_size":512, "align":2097152, "blockdev":"pmem0.1" } real 0m47.517s user 0m0.209s sys 0m26.879s root@QEMUCXL6060pmem:~# time ndctl create-namespace --mode=fsdax --region=region1 --size=128M { "dev":"namespace1.1", "mode":"fsdax", "map":"dev", "size":"124.00 MiB (130.02 MB)", "uuid":"13bc8de3-53d3-4c3d-b252-be7efefe80ee", "sector_size":512, "align":2097152, "blockdev":"pmem1.1" } real 0m33.459s user 0m0.243s sys 0m13.590s root@QEMUCXL6060pmem:~# ndctl list [ { "dev":"namespace1.0", "mode":"fsdax", "map":"dev", "size":262144000, "uuid":"6b9083c9-cb1a-447b-894d-fdfd2f3dbed2", "sector_size":512, "align":2097152, "blockdev":"pmem1" }, { "dev":"namespace1.1", "mode":"fsdax", "map":"dev", "size":130023424, "uuid":"13bc8de3-53d3-4c3d-b252-be7efefe80ee", "sector_size":512, "align":2097152, "blockdev":"pmem1.1" }, { "dev":"namespace0.1", "mode":"fsdax", "map":"dev", "size":262144000, "uuid":"c2071802-8c24-4f9c-a6c1-f6bb6589e561", "sector_size":512, "align":2097152, "blockdev":"pmem0.1" }, { "dev":"namespace0.0", "mode":"fsdax", "map":"dev", "size":130023424, "uuid":"3f6dcdc5-d289-4b0c-ad16-82636c82bec1", "sector_size":512, "align":2097152, "blockdev":"pmem0" } ] 5. Re-Start Qemu and we could see - Region persistency using "cxl list" - Namespace persistency using "ndctl list" and cat /proc/iomem root@QEMUCXL6060pmem:~# cat /proc/iomem a90000000-b8fffffff : CXL Window 0 a90000000-aafffffff : Persistent Memory a90000000-aafffffff : region0 a90000000-a97ffffff : namespace0.0 a98000000-aa7ffffff : namespace0.1 ab0000000-acfffffff : Persistent Memory ab0000000-acfffffff : region1 ab0000000-abfffffff : namespace1.0 ac0000000-ac7ffffff : namespace1.1 - NOTE: We can see some lag in restart, Its WIP 6. Also verify LSA version using "ndctl read-labels -j nmem0 -u" root@QEMUCXL6060pmem:~# ndctl read-labels -j nmem0 { "dev":"nmem0", "index":[ { "signature":"NAMESPACE_INDEX", "major":2, "minor":1, "labelsize":256, "seq":2, "nslot":4090 }, { "signature":"NAMESPACE_INDEX", "major":2, "minor":1, "labelsize":256, "seq":1, "nslot":4090 } ], "label":[ { "type":"68bb2c0a-5a77-4937-9f85-3caf41a0f93c", "uuid":"9a26b9ce-a859-4a63-b1b7-fd176105770d", "name":"", "flags":8, "nrange":1, "position":0, "dpa":134217728, "rawsize":268435456, "slot":0, "align":0, "region_uuid":"de512bdc-9731-4e5f-838c-be2e9b94ea72", "abstraction_uuid":"266400ba-fb9f-4677-bcb0-968f11d0d225", "lbasize":512 }, { "type":"529d7c61-da07-47c4-a93f-ecdf2c06f444", "uuid":"de512bdc-9731-4e5f-838c-be2e9b94ea72", "flags":0, "nlabel":1, "position":0, "dpa":0, "rawsize":536870912, "hpa":45365592064, "slot":1, "interleave granularity":256, "align":0 }, { "type":"68bb2c0a-5a77-4937-9f85-3caf41a0f93c", "uuid":"a90d211a-b28d-48c7-bfe7-99560d3825ef", "name":"", "flags":0, "nrange":1, "position":0, "dpa":0, "rawsize":134217728, "slot":2, "align":0, "region_uuid":"de512bdc-9731-4e5f-838c-be2e9b94ea72", "abstraction_uuid":"266400ba-fb9f-4677-bcb0-968f11d0d225", "lbasize":512 }, { "type":"68bb2c0a-5a77-4937-9f85-3caf41a0f93c", "uuid":"9a26b9ce-a859-4a63-b1b7-fd176105770d", "name":"", "flags":0, "nrange":1, "position":0, "dpa":134217728, "rawsize":268435456, "slot":3, "align":0, "region_uuid":"de512bdc-9731-4e5f-838c-be2e9b94ea72", "abstraction_uuid":"266400ba-fb9f-4677-bcb0-968f11d0d225", "lbasize":512 } ] } read 1 nmem - NOTE: We have following UUID types as per CXL Spec "type":"529d7c61-da07-47c4-a93f-ecdf2c06f444" is region label "type":"68bb2c0a-5a77-4937-9f85-3caf41a0f93c" is namespace label Limitation (WIP): ================ Current changes only support interleave way == 1 Observation: ============ First time namespace creation using ndctl takes around 10 to 20 second time while executing "devm_memremap_pages" at [3] As using this patchset, after auto region creation, namespace creation is happening in boot sequence (if nvdimm and cxl drivers are static), It is therefore boot sequence is increased by around 10 to 20 sec. [1]: https://lore.kernel.org/all/163116432405.2460985.5547867384570123403.st...@dwillia2-desk3.amr.corp.intel.com/ [2]: https://github.com/neerajoss/ndctl/tree/linux-cxl/CXL_LSA_2.1_Support [3]: https://elixir.bootlin.com/linux/v6.13.7/source/drivers/nvdimm/pmem.c#L520 Neeraj Kumar (20): nvdimm/label: Introduce NDD_CXL_LABEL flag to set cxl label format nvdimm/label: Prep patch to accommodate cxl lsa 2.1 support nvdimm/namespace_label: Add namespace label changes as per CXL LSAv2.1 nvdimm/label: CXL labels skip the need for 'interleave-set cookie' nvdimm/region_label: Add region label updation routine nvdimm/region_label: Add region label deletion routine nvdimm/namespace_label: Update namespace init_labels and its region_uuid nvdimm/label: Include region label in slot validation nvdimm/namespace_label: Skip region label during ns label DPA reservation nvdimm/region_label: Preserve cxl region information from region label nvdimm/region_label: Export routine to fetch region information nvdimm/namespace_label: Skip region label during namespace creation cxl/mem: Refactor cxl pmem region auto-assembling cxl/region: Add cxl pmem region creation routine for region persistency cxl: Add a routine to find cxl root decoder on cxl bus cxl/mem: Preserve cxl root decoder during mem probe cxl/pmem: Preserve region information into nd_set cxl/pmem: Add support of cxl lsa 2.1 support in cxl pmem cxl/pmem_region: Prep patch to accommodate pmem_region attributes cxl/pmem_region: Add cxl region label updation and deletion device attributes drivers/cxl/Kconfig | 12 + drivers/cxl/core/Makefile | 1 + drivers/cxl/core/core.h | 8 +- drivers/cxl/core/pmem_region.c | 325 ++++++++++++++++++++++++++ drivers/cxl/core/port.c | 72 +++++- drivers/cxl/core/region.c | 383 +++++++++++++++--------------- drivers/cxl/cxl.h | 46 +++- drivers/cxl/cxlmem.h | 1 + drivers/cxl/mem.c | 27 ++- drivers/cxl/pmem.c | 72 +++++- drivers/cxl/port.c | 38 --- drivers/nvdimm/dimm.c | 5 + drivers/nvdimm/dimm_devs.c | 28 +++ drivers/nvdimm/label.c | 403 ++++++++++++++++++++++++++++---- drivers/nvdimm/label.h | 20 +- drivers/nvdimm/namespace_devs.c | 149 ++++++++---- drivers/nvdimm/nd-core.h | 2 + drivers/nvdimm/nd.h | 81 ++++++- drivers/nvdimm/region_devs.c | 5 + include/linux/libnvdimm.h | 28 +++ tools/testing/cxl/Kbuild | 1 + 21 files changed, 1364 insertions(+), 343 deletions(-) create mode 100644 drivers/cxl/core/pmem_region.c base-commit: 448a60e85ae2afe2cb760f5d2ed2c8a49d2bd1b4 -- 2.34.1
