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Message-ID: <Z6o87wa-tabDy34V@fan> Date: Mon, 10 Feb 2025 09:52:47 -0800 From: Fan Ni <nifan.cxl@...il.com> To: shiju.jose@...wei.com Cc: linux-edac@...r.kernel.org, linux-cxl@...r.kernel.org, linux-acpi@...r.kernel.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org, bp@...en8.de, tony.luck@...el.com, rafael@...nel.org, lenb@...nel.org, mchehab@...nel.org, dan.j.williams@...el.com, dave@...olabs.net, jonathan.cameron@...wei.com, dave.jiang@...el.com, alison.schofield@...el.com, vishal.l.verma@...el.com, ira.weiny@...el.com, david@...hat.com, Vilas.Sridharan@....com, leo.duran@....com, Yazen.Ghannam@....com, rientjes@...gle.com, jiaqiyan@...gle.com, Jon.Grimm@....com, dave.hansen@...ux.intel.com, naoya.horiguchi@....com, james.morse@....com, jthoughton@...gle.com, somasundaram.a@....com, erdemaktas@...gle.com, pgonda@...gle.com, duenwen@...gle.com, gthelen@...gle.com, wschwartz@...erecomputing.com, dferguson@...erecomputing.com, wbs@...amperecomputing.com, nifan.cxl@...il.com, tanxiaofei@...wei.com, prime.zeng@...ilicon.com, roberto.sassu@...wei.com, kangkang.shen@...urewei.com, wanghuiqiang@...wei.com, linuxarm@...wei.com, a.manzanares@...sung.com, nmtadam.samsung@...il.com, anisa.su887@...il.com Subject: Re: [PATCH v19 00/15] EDAC: Scrub: introduce generic EDAC RAS control feature driver + CXL/ACPI-RAS2 drivers On Fri, Feb 07, 2025 at 02:44:29PM +0000, shiju.jose@...wei.com wrote: > From: Shiju Jose <shiju.jose@...wei.com> > > The CXL patches of this series has dependency on Dave's CXL fwctl > series [1]. > > The code is based on v3 of CXL fwctl series [1] posted by Dave and > v3 of FWCTL series [2] posted by Jason and rebased on top of > v6.14-rc1. > > [1]: https://lore.kernel.org/linux-cxl/20250204220430.4146187-1-dave.jiang@intel.com/ > [2]: https://lore.kernel.org/linux-cxl/0-v3-960f17f90f17+516-fwctl_jgg@nvidia.com/#r > > > 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/ > Hi Shiju, Is this series the same as in branch https://github.com/shijujose4/linux/tree/edac-enhancement-ras-features_v19? I hit some compile errors wen trying to test with the above branch directly. Here are two cases where I found the code cannot compile. Please check if it is a false alarm. Case 1: CONFIG_CXL_RAS_FEATURES=m fan:~/cxl/linux-edac$ cat .config | egrep -i "edac|cxl|ras" | grep -v "^#" CONFIG_ACPI_RAS2=y CONFIG_ACPI_APEI_EINJ_CXL=y CONFIG_PCIEAER_CXL=y CONFIG_CXL_BUS=y CONFIG_CXL_PCI=y CONFIG_CXL_MEM_RAW_COMMANDS=y CONFIG_CXL_ACPI=y CONFIG_CXL_PMEM=y CONFIG_CXL_MEM=y CONFIG_CXL_FWCTL=y CONFIG_CXL_PORT=y CONFIG_CXL_SUSPEND=y CONFIG_CXL_REGION=y CONFIG_CXL_REGION_INVALIDATION_TEST=y CONFIG_CXL_RAS_FEATURES=m CONFIG_MMC_SDHCI_OF_ARASAN=y CONFIG_EDAC_ATOMIC_SCRUB=y CONFIG_EDAC_SUPPORT=y CONFIG_EDAC=y CONFIG_EDAC_LEGACY_SYSFS=y CONFIG_EDAC_DEBUG=y CONFIG_EDAC_DECODE_MCE=m CONFIG_EDAC_GHES=m CONFIG_EDAC_SCRUB=y CONFIG_EDAC_ECS=y CONFIG_EDAC_MEM_REPAIR=y CONFIG_EDAC_IGEN6=m CONFIG_RAS=y CONFIG_MEM_ACPI_RAS2=y CONFIG_DEV_DAX_CXL=m fan:~/cxl/linux-edac$ fan:~/cxl/linux-edac$ make -j16 mkdir -p /home/fan/cxl/linux-edac/tools/objtool && make O=/home/fan/cxl/linux-edac subdir=tools/objtool --no-print-directory -C objtool CALL scripts/checksyscalls.sh INSTALL libsubcmd_headers UPD include/generated/utsversion.h CC init/version-timestamp.o KSYMS .tmp_vmlinux0.kallsyms.S AS .tmp_vmlinux0.kallsyms.o LD .tmp_vmlinux1 ld: vmlinux.o: in function `cxl_region_probe': /home/fan/cxl/linux-edac/drivers/cxl/core/region.c:3456:(.text+0x7b296f): undefined reference to `devm_cxl_region_edac_register' ld: vmlinux.o: in function `cxl_mem_probe': /home/fan/cxl/linux-edac/drivers/cxl/mem.c:188:(.text+0x7b8ad1): undefined reference to `devm_cxl_memdev_edac_register' make[2]: *** [scripts/Makefile.vmlinux:77: vmlinux] Error 1 make[1]: *** [/home/fan/cxl/linux-edac/Makefile:1226: vmlinux] Error 2 make: *** [Makefile:251: __sub-make] Error 2 When compile with CONFIG_CXL_RAS_FEATURES=y, it can compile. CASE 2: CONFIG_EDAC=m fan:~/cxl/linux-edac$ cat .config | egrep -i "edac|cxl|ras" | grep -v "^#" CONFIG_CRASH_RESERVE=y CONFIG_CRASH_DUMP=y CONFIG_CRASH_HOTPLUG=y CONFIG_CRASH_MAX_MEMORY_RANGES=8192 CONFIG_ARCH_SUPPORTS_CRASH_DUMP=y CONFIG_ARCH_DEFAULT_CRASH_DUMP=y CONFIG_ARCH_SUPPORTS_CRASH_HOTPLUG=y CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION=y CONFIG_ACPI_RAS2=y CONFIG_ACPI_APEI_EINJ_CXL=y CONFIG_PCIEAER_CXL=y CONFIG_CXL_BUS=y CONFIG_CXL_PCI=y CONFIG_CXL_MEM_RAW_COMMANDS=y CONFIG_CXL_ACPI=y CONFIG_CXL_PMEM=y CONFIG_CXL_MEM=y CONFIG_CXL_FWCTL=y CONFIG_CXL_PORT=y CONFIG_CXL_SUSPEND=y CONFIG_CXL_REGION=y CONFIG_CXL_REGION_INVALIDATION_TEST=y CONFIG_CXL_RAS_FEATURES=y CONFIG_MMC_SDHCI_OF_ARASAN=y CONFIG_EDAC_ATOMIC_SCRUB=y CONFIG_EDAC_SUPPORT=y CONFIG_EDAC=m CONFIG_EDAC_LEGACY_SYSFS=y CONFIG_EDAC_DEBUG=y CONFIG_EDAC_DECODE_MCE=m CONFIG_EDAC_GHES=m CONFIG_EDAC_SCRUB=y CONFIG_EDAC_ECS=y CONFIG_EDAC_MEM_REPAIR=y CONFIG_EDAC_IGEN6=m CONFIG_RAS=y CONFIG_MEM_ACPI_RAS2=y CONFIG_DEV_DAX_CXL=m fan:~/cxl/linux-edac$ fan:~/cxl/linux-edac$ make -j16 mkdir -p /home/fan/cxl/linux-edac/tools/objtool && make O=/home/fan/cxl/linux-edac subdir=tools/objtool --no-print-directory -C objtool CALL scripts/checksyscalls.sh INSTALL libsubcmd_headers UPD include/generated/utsversion.h CC init/version-timestamp.o KSYMS .tmp_vmlinux0.kallsyms.S AS .tmp_vmlinux0.kallsyms.o LD .tmp_vmlinux1 ld: vmlinux.o: in function `devm_cxl_region_edac_register': /home/fan/cxl/linux-edac/drivers/cxl/core/memfeature.c:1720:(.text+0x7b665d): undefined reference to `edac_dev_register' ld: vmlinux.o: in function `devm_cxl_memdev_edac_register': /home/fan/cxl/linux-edac/drivers/cxl/core/memfeature.c:1697:(.text+0x7b7241): undefined reference to `edac_dev_register' ld: vmlinux.o: in function `ras2_probe': /home/fan/cxl/linux-edac/drivers/ras/acpi_ras2.c:363:(.text+0xb0ecc8): undefined reference to `edac_dev_register' make[2]: *** [scripts/Makefile.vmlinux:77: vmlinux] Error 1 make[1]: *** [/home/fan/cxl/linux-edac/Makefile:1226: vmlinux] Error 2 make: *** [Makefile:251: __sub-make] Error 2 Fan > Augmenting EDAC for controlling RAS features > ============================================ > The proposed expansion of EDAC for controlling RAS features and > exposing features control attributes to userspace in sysfs. > Some Examples: > - Scrub control > - Error Check Scrub (ECS) control > - ACPI RAS2 features > - Post Package Repair (PPR) control > - Memory Sparing Repair control etc. > > High level design is illustrated in the following diagram. > > +-----------------------------------------------+ > | Userspace - Rasdaemon | > | +-------------+ | > | | RAS CXL mem | +---------------+ | > | |error handler|---->| | | > | +-------------+ | RAS dynamic | | > | +-------------+ | scrub, memory | | > | | RAS memory |---->| repair control| | > | |error handler| +----|----------+ | > | +-------------+ | | > +--------------------------|--------------------+ > | > | > +-------------------------------|------------------------------+ > | Kernel EDAC extension for | controlling RAS Features | > |+------------------------------|----------------------------+ | > || EDAC Core Sysfs EDAC| Bus | | > || +--------------------------|---------------------------+| | > || |/sys/bus/edac/devices/<dev>/scrubX/ | | EDAC device || | > || |/sys/bus/edac/devices/<dev>/ecsX/ |<->| EDAC MC || | > || |/sys/bus/edac/devices/<dev>/repairX | | EDAC sysfs || | > || +---------------------------|--------------------------+| | > || EDAC|Bus | | > || | | | > || +----------+ Get feature | Get feature | | > || | | desc +---------|------+ desc +----------+ | | > || |EDAC scrub|<-----| EDAC device | | | | | > || +----------+ | driver- RAS |----->| EDAC mem | | | > || +----------+ | feature control| | repair | | | > || | |<-----| | +----------+ | | > || |EDAC ECS | +---------|------+ | | > || +----------+ Register RAS|features | | > || ______________________|_____________ | | > |+---------|---------------|------------------|--------------+ | > | +-------|----+ +-------|-------+ +----|----------+ | > | | | | CXL mem driver| | Client driver | | > | | ACPI RAS2 | | scrub, ECS, | | memory repair | | > | | driver | | sparing, PPR | | features | | > | +-----|------+ +-------|-------+ +------|--------+ | > | | | | | > +--------|-----------------|--------------------|--------------+ > | | | > +--------|-----------------|--------------------|--------------+ > | +---|-----------------|--------------------|-------+ | > | | | | > | | Platform HW and Firmware | | > | +--------------------------------------------------+ | > +--------------------------------------------------------------+ > > > 1. EDAC RAS Features components - Create feature specific descriptors. > for example, EDAC scrub, EDAC ECS, EDAC memory repair in the above > diagram. > 2. EDAC device driver for controlling RAS Features - Get feature's attr > descriptors from EDAC RAS feature component and registers device's > RAS features with EDAC bus and expose the feature's sysfs attributes > under the sysfs EDAC bus. > 3. RAS dynamic scrub controller - Userspace sample module added for scrub > control in rasdaemon to issue scrubbing when excess number of memory > errors are reported in a short span of time. > > The added EDAC feature specific components (e.g. EDAC scrub, EDAC ECS, > EDAC memory repair etc) do callbacks to the parent driver (e.g. CXL > driver, ACPI RAS driver etc) for the controls rather than just letting the > caller deal with it because of the following reasons. > 1. Enforces a common API across multiple implementations can do that > via review, but that's not generally gone well in the long run for > subsystems that have done it (several have later moved to callback > and feature list based approaches). > 2. Gives a path for 'intercepting' in the EDAC feature driver. > An example for this is that we could intercept PPR repair calls > and sanity check that the memory in question is offline before > passing back to the underlying code. Sure we could rely on doing > that via some additional calls from the parent driver, but the > ABI will get messier. > 3. (Speculative) we may get in kernel users of some features in the > long run. > > More details of the common RAS features are described in the following > sections. > > Memory Scrubbing > ================ > Increasing DRAM size and cost has made memory subsystem reliability > an important concern. These modules are used where potentially > corrupted data could cause expensive or fatal issues. Memory errors are > one of the top hardware failures that cause server and workload crashes. > > Memory scrub is a feature where an ECC engine reads data from > each memory media location, corrects with an ECC if necessary and > writes the corrected data back to the same memory media location. > > The memory DIMMs could be scrubbed at a configurable rate to detect > uncorrected memory errors and attempts to recover from detected memory > errors providing the following benefits. > - Proactively scrubbing memory DIMMs reduces the chance of a correctable > error becoming uncorrectable. > - Once detected, uncorrected errors caught in unallocated memory pages are > isolated and prevented from being allocated to an application or the OS. > - The probability of software/hardware products encountering memory > errors is reduced. > Some details of background can be found in Reference [5]. > > There are 2 types of memory scrubbing, > 1. Background (patrol) scrubbing of the RAM whilst the RAM is otherwise > idle. > 2. On-demand scrubbing for a specific address range/region of memory. > > There are several types of interfaces to HW memory scrubbers > identified such as ACPI NVDIMM ARS(Address Range Scrub), CXL memory > device patrol scrub, CXL DDR5 ECS, ACPI RAS2 memory scrubbing. > > The scrub control varies between different memory scrubbers. To allow > for standard userspace tooling there is a need to present these controls > with a standard ABI. > > Introduce generic memory EDAC scrub control which allows user to control > underlying scrubbers in the system via generic sysfs scrub control > interface. The common sysfs scrub control interface abstracts the control > of an arbitrary scrubbing functionality to a common set of functions. > > Use case of common scrub control feature > ======================================== > 1. There are several types of interfaces to HW memory scrubbers identified > such as ACPI NVDIMM ARS(Address Range Scrub), CXL memory device patrol > scrub, CXL DDR5 ECS, ACPI RAS2 memory scrubbing features and software > based memory scrubber(discussed in the community Reference [5]). > Also some scrubbers support controlling (background) patrol scrubbing > (ACPI RAS2, CXL) and/or on-demand scrubbing(ACPI RAS2, ACPI ARS). > However the scrub controls varies between memory scrubbers. Thus there > is a requirement for a standard generic sysfs scrub controls exposed > to userspace for the seamless control of the HW/SW scrubbers in > the system by admin/scripts/tools etc. > 2. Scrub controls in user space allow the user to disable the scrubbing > in case disabling of the background patrol scrubbing or changing the > scrub rate are needed for other purposes such as performance-aware > operations which requires the background operations to be turned off > or reduced. > 3. Allows to perform on-demand scrubbing for specific address range if > supported by the scrubber. > 4. User space tools controls scrub the memory DIMMs regularly at a > configurable scrub rate using the sysfs scrub controls discussed help, > - to detect uncorrectable memory errors early before user accessing > memory, which helps to recover the detected memory errors. > - reduces the chance of a correctable error becoming uncorrectable. > 5. Policy control for hotplugged memory. There is not necessarily a system > wide bios or similar in the loop to control the scrub settings on a CXL > device that wasn't there at boot. What that setting should be is a policy > decision as we are trading of reliability vs performance - hence it should > be in control of userspace. As such, 'an' interface is needed. Seems more > sensible to try and unify it with other similar interfaces than spin > yet another one. > > The draft version of userspace code added in rasdaemon for dynamic scrub > control, based on frequency of memory errors reported to userspace, tested > for CXL device based patrol scrubbing feature and ACPI RAS2 based > scrubbing feature. > > https://github.com/shijujose4/rasdaemon/tree/ras_feature_control > > ToDO: For memory repair features, such as PPR, memory sparing, rasdaemon > collates records and decides to replace a row if there are lots of > corrected errors, or a single uncorrected error or error record received > with 'maintenance need' flag set as in some CXL event records. > > Comparison of scrubbing features > ================================ > +--------------+-----------+-----------+-----------+-----------+ > | | ACPI | CXL patrol| CXL ECS | ARS | > | Name | RAS2 | scrub | | | > +--------------+-----------+-----------+-----------+-----------+ > | | | | | | > | On-demand | Supported | No | No | Supported | > | Scrubbing | | | | | > | | | | | | > +--------------+-----------+-----------+-----------+-----------+ > | | | | | | > | Background | Supported | Supported | Supported | No | > | scrubbing | | | | | > | | | | | | > +--------------+-----------+-----------+-----------+-----------+ > | | | | | | > | Mode of | Scrub ctrl| per device| per memory| Unknown | > | scrubbing | per NUMA | | media | | > | | domain. | | | | > +--------------+-----------+-----------+-----------+-----------+ > | | | | | | > | Query scrub | Supported | Supported | Supported | Supported | > | capabilities | | | | | > | | | | | | > +--------------+-----------+-----------+-----------+-----------+ > | | | | | | > | Setting | Supported | No | No | Supported | > | address range| | | | | > | | | | | | > +--------------+-----------+-----------+-----------+-----------+ > | | | | | | > | Setting | Supported | Supported | No | No | > | scrub rate | | | | | > | | | | | | > +--------------+-----------+-----------+-----------+-----------+ > | | | | | | > | Unit for | Not | in hours | No | No | > | scrub rate | Defined | | | | > | | | | | | > +--------------+-----------+-----------+-----------+-----------+ > | | Supported | | | | > | Scrub | on-demand | No | No | Supported | > | status/ | scrubbing | | | | > | Completion | only | | | | > +--------------+-----------+-----------+-----------+-----------+ > | UC error | |CXL general|CXL general| ACPI UCE | > | reporting | Exception |media/DRAM |media/DRAM | notify and| > | | |event/media|event/media| query | > | | |scan? |scan? | ARS status| > +--------------+-----------+-----------+-----------+-----------+ > > CXL Memory Scrubbing features > ============================= > CXL spec r3.1 section 8.2.9.9.11.1 describes the memory device patrol scrub > control feature. The device patrol scrub proactively locates and makes > corrections to errors in regular cycle. The patrol scrub control allows the > request to configure patrol scrubber's input configurations. > > The patrol scrub control allows the requester to specify the number of > hours in which the patrol scrub cycles must be completed, provided that > the requested number is not less than the minimum number of hours for the > patrol scrub cycle that the device is capable of. In addition, the patrol > scrub controls allow the host to disable and enable the feature in case > disabling of the feature is needed for other purposes such as > performance-aware operations which require the background operations to be > turned off. > > The Error Check Scrub (ECS) is a feature defined in JEDEC DDR5 SDRAM > Specification (JESD79-5) and allows the DRAM to internally read, correct > single-bit errors, and write back corrected data bits to the DRAM array > while providing transparency to error counts. > > The DDR5 device contains number of memory media FRUs per device. The > DDR5 ECS feature and thus the ECS control driver supports configuring > the ECS parameters per FRU. > > ACPI RAS2 Hardware-based Memory Scrubbing > ========================================= > ACPI spec 6.5 section 5.2.21 ACPI RAS2 describes ACPI RAS2 table > provides interfaces for platform RAS features and supports independent > RAS controls and capabilities for a given RAS feature for multiple > instances of the same component in a given system. > Memory RAS features apply to RAS capabilities, controls and operations > that are specific to memory. RAS2 PCC sub-spaces for memory-specific RAS > features have a Feature Type of 0x00 (Memory). > > The platform can use the hardware-based memory scrubbing feature to expose > controls and capabilities associated with hardware-based memory scrub > engines. The RAS2 memory scrubbing feature supports following as per spec, > - Independent memory scrubbing controls for each NUMA domain, identified > using its proximity domain. > Note: However AmpereComputing has single entry repeated as they have > centralized controls. > - Provision for background (patrol) scrubbing of the entire memory system, > as well as on-demand scrubbing for a specific region of memory. > > ACPI Address Range Scrubbing(ARS) > ================================ > ARS allows the platform to communicate memory errors to system software. > This capability allows system software to prevent accesses to addresses > with uncorrectable errors in memory. ARS functions manage all NVDIMMs > present in the system. Only one scrub can be in progress system wide > at any given time. > Following functions are supported as per the specification. > 1. Query ARS Capabilities for a given address range, indicates platform > supports the ACPI NVDIMM Root Device Unconsumed Error Notification. > 2. Start ARS triggers an Address Range Scrub for the given memory range. > Address scrubbing can be done for volatile memory, persistent memory, > or both. > 3. Query ARS Status command allows software to get the status of ARS, > including the progress of ARS and ARS error record. > 4. Clear Uncorrectable Error. > 5. Translate SPA > 6. ARS Error Inject etc. > Note: Support for ARS is not added in this series because to reduce the > line of code for review and could be added after initial code is merged. > We'd like feedback on whether this is of interest to ARS community? > > Post Package Repair(PPR) > ======================== > PPR (Post Package Repair) maintenance operation requests the memory device > to perform a repair operation on its media if supported. A memory device > may support two types of PPR: Hard PPR (hPPR), for a permanent row repair, > and Soft PPR (sPPR), for a temporary row repair. sPPR is much faster than > hPPR, but the repair is lost with a power cycle. During the execution of a > PPR maintenance operation, a memory device, may or may not retain data and > may or may not be able to process memory requests correctly. sPPR maintenance > operation may be executed at runtime, if data is retained and memory requests > are correctly processed. hPPR maintenance operation may be executed only at > boot because data would not be retained. > > Use cases of common PPR control feature > ======================================= > 1. The Soft PPR (sPPR) and Hard PPR (hPPR) share similar control interfaces, > thus there is a requirement for a standard generic sysfs PPR controls exposed > to userspace for the seamless control of the PPR features in the system by the > admin/scripts/tools etc. > 2. When a CXL device identifies a failure on a memory component, the device > may inform the host about the need for a PPR maintenance operation by using > an event record, where the maintenance needed flag is set. The event record > specifies the DPA that should be repaired. Kernel reports the corresponding > cxl general media or DRAM trace event to userspace. The userspace tool, > for reg. rasdaemon initiate a PPR maintenance operation in response to a > device request using the sysfs PPR control. > 3. User space tools, for eg. rasdaemon, do request PPR on a memory region > when uncorrected memory error or excess corrected memory errors reported > on that memory. > 4. Likely multiple instances of PPR present per memory device. > > Memory Sparing > ============== > Memory sparing is defined as a repair function that replaces a portion of > memory with a portion of functional memory at that same DPA. User space > tool, e.g. rasdaemon, may request the sparing operation for a given > address for which the uncorrectable error is reported. In CXL, > (CXL spec 3.1 section 8.2.9.7.1.4) subclasses for sparing operation vary > in terms of the scope of the sparing being performed. The cacheline sparing > subclass refers to a sparing action that can replace a full cacheline. > Row sparing is provided as an alternative to PPR sparing functions and its > scope is that of a single DDR row. Bank sparing allows an entire bank to > be replaced. Rank sparing is defined as an operation in which an entire > DDR rank is replaced. > > Series adds, > 1. EDAC device driver extended for controlling RAS features, EDAC scrub > driver, EDAC ECS driver, EDAC memory repair driver supports memory > scrub control, ECS control, memory repair(PPR, sparing) control > respectively. > 2. Several common patches from Dave's cxl/fwctl series. > 3. Support for CXL feature mailbox commands, which is used by CXL device > scrubbing and memory repair features. > 4. CXL features driver supporting patrol scrub control (device and > region based). > 5. CXL features driver supporting ECS control feature. > 6. ACPI RAS2 driver adds OS interface for RAS2 communication through > PCC mailbox and extracts ACPI RAS2 feature table (RAS2) and > create platform device for the RAS memory features, which binds > to the memory ACPI RAS2 driver. > 7. Memory ACPI RAS2 driver gets the PCC subspace for communicating > with the ACPI compliant platform supports ACPI RAS2. Add callback > functions and registers with EDAC device to support user to > control the HW patrol scrubbers exposed to the kernel via the > ACPI RAS2 table. > 8. Support for CXL maintenance mailbox command, which is used by > CXL device memory repair feature. > 9. CXL features drivers supporting PPR and memory sparing features. > Note: There are other PPR, memory sparing drivers to come. > > Open Questions based on feedbacks from the community: > 1. Jonathan: > - Any need for discoverability of capability to scan different regions, > such as global PA space to userspace. Left as future extension. > > 2. Jiaqi: > - STOP_PATROL_SCRUBBER from RAS2 must be blocked and, must not be exposed to > OS/userspace. Stopping patrol scrubber is unacceptable for platform where > OEM has enabled patrol scrubber, because the patrol scrubber is a key part > of logging and is repurposed for other RAS actions. > If the OEM does not want to expose this control, they should lock it down so the > interface is not exposed to the OS. These features are optional after all. > - "Requested Address Range"/"Actual Address Range" (region to scrub) is a > similarly bad thing to expose in RAS2. > If the OEM does not want to expose this, they should lock it down so the > interface is not exposed to the OS. These features are optional after all. > As per LPC discussion, support for stop and attributes for addr range > to be exposed to the userspace. > 3. Borislav: > - How the scrub control exposed to userspace will be used? > POC added in rasdaemon with dynamic scrub control for CXL memory media > errors and memory errors reported to userspace. > https://github.com/shijujose4/rasdaemon/tree/scrub_control_6_june_2024 > - Is the scrub interface is sufficient for the use cases? > - Who is going to use scrub controls tools/admin/scripts? > 1) Rasdaemon for dynamic control > 2) Udev script for more static 'defaults' on hotplug etc. > - Sample userspace code for memory repair feature > https://lore.kernel.org/lkml/20250207143028.1865-1-shiju.jose@huawei.com/ > - Sample boot-script for memory repair > https://lore.kernel.org/lkml/20250207143028.1865-5-shiju.jose@huawei.com/ > > > 4. PPR > - For PPR, rasdaemon collates records and decides to replace a row if there > are lots of corrected errors, or a single uncorrected error or error record > received with maintenance request flag set as in CXL DRAM error record. > - sPPR more or less startup only (so faking hPPR) or actually useful > in a running system (if not the safe version that keeps everything > running whilst replacement is ongoing) > - Is future proofing for multiple PPR units useful given we've mashed > together hPPR and sPPR for CXL. > > Implementation > ============== > 1. Linux kernel > Version 19 of kernel implementations of RAS features control is available in, > https://github.com/shijujose4/linux.git > Branch: edac-enhancement-ras-features_v19 > > The code is based on v3 of CXL fwctl series [1] posted by Dave and > v3 of FWCTL series [2] posted by Jason and rebased on top of > v6.14-rc1. > > [1]: https://lore.kernel.org/linux-cxl/20250204220430.4146187-1-dave.jiang@intel.com/ > [2]: https://lore.kernel.org/linux-cxl/0-v3-960f17f90f17+516-fwctl_jgg@nvidia.com/#r > > 2. QEMU emulation > QEMU for CXL RAS features implementation is available in, > https://gitlab.com/shiju.jose/qemu.git > Branch: cxl-ras-features-2024-10-24 > > 3. Userspace - rasdaemon > 3.1. Memory scrubbing > The draft version of userspace sample code for dynamic scrub control, > based on frequency of memory errors reported to userspace, is added > in rasdaemon and enabled, tested for CXL device based patrol scrubbing > feature and ACPI RAS2 based scrubbing feature. This required updation > for the latest sysfs scrub interface. > https://github.com/shijujose4/rasdaemon/tree/ras_feature_control > > 3.2. Memory repair > - Sample userspace code for memory repair feature [3]. > > - Sample boot-script for 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/ > > References: > 1. ACPI spec r6.5 section 5.2.21 ACPI RAS2. > 2. ACPI spec r6.5 section 9.19.7.2 ARS. > 3. CXL spec r3.1 8.2.9.9.11.1 Device patrol scrub control feature > 4. CXL spec r3.1 8.2.9.9.11.2 DDR5 ECS feature > 5. CXL spec r3.1 8.2.9.7.1.1 PPR Maintenance Operations > 6. CXL spec r3.1 8.2.9.7.2.1 sPPR Feature Discovery and Configuration > 7. CXL spec r3.1 8.2.9.7.2.2 hPPR Feature Discovery and Configuration > 8. Background information about kernel support for memory scan, memory > error detection and ACPI RASF. > https://lore.kernel.org/all/20221103155029.2451105-1-jiaqiyan@google.com/ > 9. Discussions on RASF: > https://lore.kernel.org/lkml/20230915172818.761-1-shiju.jose@huawei.com/#r > > Changes > ======= > v18 -> v19: > 1. Added config EDAC_SCRUB, EDAC_ECS and EDAC_MEM_REPAIR and > associated changes for feedback from Borislav. > > 2. Control attributes related to the memory-sparing features > in EDAC memory repair moved into another patch. > > 3. Feedback from Dan on CXL patches, > - Added more comments to the examples given for CXL features > in the Documentation/edac/scrub.rst and > Documentation/edac/memory_repair.rst > - Removed CXL_PCI dependency for the CONFIG_CXL_RAS_FEATURES > - Updated description for CONFIG_CXL_RAS_FEATURES ad Dan suggested. > - Added specification reference comments for CXL patrol scrub and ECS. > - kmalloc -> kzalloc > - Added comment and/or hold lock for region based memory scrubbing code. > In addition, Added common helper functions to hold and release rwsem for read. > - Removed unwanted logs and dev_err -> dev_dbg in other places. > - Added separate helper functions for cxl_mem_ras_features_init() for memdev and region. > This solved a bug pointed by Dan in region based init. > - Replaced "cxl_region%d", cxlr->id with "%s_%s", "cxl", dev_name(&cxlr->dev) > - removed module soft dep on cxl_features. > > 4. Mauro's review comments, > - Fixed ABI documentation issues, update diagram & table for ReST > and update .rst docs licensing update. > - Changed sysfs memory repair_type from integer to string format. > - Reorder, diagram and table updates in the patch[0]. > > 5. Feedback on memory repair from community and Jonathan, > - Removed min and max attributes for range from edac mem repair for > bank, rank, channel,..etc. those were added in v16. > - For range attributes series continue to use min_ and max_ > attributes. For eg. scrub rate in EDAC scrub and dpa & hpa in > EDAC memory repair. Not sure to change or not to the scheme > suggested by Borislav for exposing range in sysfs. > - CXL memory repair - Added check for memory if offline and memory > to reapir with attributes reported in ev record in the current > boot. Otherwise do not issue repair command. > etc. > > 6. Feedback from Jonathan from internal review, > - Fixes in the .rst documentations > - Update date in file headers. > - Change 'persist_mode' in memory repair to boolean. > - Moved some enums from patch for EDAC mem repair patch to > CXL repair patches. > - Few optimizations and tidy up in RAS2 drivers. > - Removed extra return error code check for set_feature and get_feature > functions in CXL RAS code. > - Re-order structure definitions in CXL RAS driver for better packaging. > - Fixed multi line comment format in CXL memory repair drivers. > - Removed support for 'query' command from the CXL memory repair drivers. > - Removed zeroing sparing attributes if spare request to the device return error. > etc. > > 7. > - The code is based on v3 of CXL fwctl series [1] posted by Dave and > v3 of FWCTL series [2] posted by Jason and rebased on top of v6.14-rc1. > - Modified CXL code for Dave's changes based on Dan's suggestions, for > input for the feature calls is mbox based. > - In addition, added separate patch for cxl_get_supported_feature_entry() > to EDAC series. > > v17 -> v18: > 1. Rebased to kernel version 6.13-rc5 > 2. Reordered patches for feedback on v17. > 3. > 3.1 Took updated patches for CXL feature infrastructure and feature commands > from Dave's cxl/features branch, debug and tested. > 3.2. RAS features in the cxl/core/memfeature.c updated for interface > changes in the CXL feature commands. > 4. Modified ACPI RAS2 code for the recent interface changes in the > PCC mbox code. > > v16 -> v17: > 1. > 1.1 Took several patches for CXL feature commands from Dave's > fwctl/cxl series and add fixes pointed by Jonathan in those patches. > 1.2. cxl/core/memfeature.c updated for interface changes in the > Get Supported Feature, Get Feature and Set Feature functions. > 1.3. Used the UUID's for RAS features in CXL features code from > include/cxl/features.h > 2. Changes based on feedbacks from Boris > - Added attributes in EDAC memory repair to return the range for DPA > and other control attributes, and added callback functions for the > DPA range in CXL PPR and memory sparing code, which is the only one > supported in the CXL. > - Removed 'query' attribute for memory repair feature. > > v15 -> v16: > 1. Changes and Fixes for feedbacks from Boris > - Modified documentations and interface file for EDAC memory repair > to add more details and use cases. > - Merged documentations to corresponding patches instead of common patch > for full documentation for better readability. > - Removed 'persist_mode_avail' attribute for memory repair feature. > 2. Changes for feedback from Dave Jiang > - Dave suggested helper function for ECS initialization in cxl/core/memfeature.c, > which added for all CXl RAS features, scrub, ECS, PPR and memory sparing features. > - Fixed endian conversion pointed by Dave in CXL memory sparing. Also I fixed > similar in CXL scrub, ECS and PPR features. > 3. Changes for feedback from Ni Fan. > - Fixed a memory leak in edac_dev_register() for memory repair feature > and few suggestions by Ni Fan. > > v14 -> v15: > 1. Changes and Fixes for feedbacks from Boris > - Added documentations for edac features, scrub and memory_repair etc > and placed in a separate patch. > - Deleted extra 2 attributes for EDAC ECS log_entry_type_per_* and > mode_counts_*. > - Rsolved issues reported in Documentation/ABI/testing/sysfs-edac-ecs. > - Deleted unused pr_ftmt() from few files. > - Fixed some formatting issues EDAC ECS code and similar in other files. > etc. > 2. Change for feedback from Dave Jiang > - In CXL code for patrol scrub control, Dave suggested replace > void *drv_data with a union of parameters in cxl_ps_get_attrs() and > similar functions. > This is fixed by replacing void *drv_data with corresponding context > structure(struct cxl_patrol_scrub_context) in CXL local functions as > struct cxl_patrol_scrub_context difficult and can't be visible in > generic EDAC control interface. Similar changes are made for CXL ECS, > CXL PPR and CXL memory sparing local functions. > > v13 -> v14: > 1. Changes and Fixes for feedback from Boris > - Check grammar of patch description. > - Changed scrub control attributes for memory scrub range to "addr" and "size". > - Fixed unreached code in edac_dev_register(). > - Removed enable_on_demand attribute from EDAC scrub control and modified > RAS2 driver for the same. > - Updated ABI documentation for EDAC scrub control. > etc. > > 2. Changes for feedback from Greg/Rafael/Jonathan for ACPI RAS2 > - Replaced platform device creation and binding with > auxiliary device creation and binding with ACPI RAS2 > memory auxiliary driver. > > 3. Changes and Fixes for feedback from Jonathan > - Fixed unreached code in edac_dev_register(). > - Optimize callback functions in CXL ECS using macros. > - Add readback attributes for the EDAC memory repair feature > and add support in the CXL driver for PPR and memory sparing. > - Add refactoring in the CXL driver for PPR and memory sparing > for query/repair maintenance commands. > - Add cxl_dpa_to_region_locked() function. > - Some more cleanups in the ACPI RAS2 and RAS2 memory drivers. > etc. > > 4. Changes and Fixes for feedback from Ni Fan > - Fixed compilation error - cxl_mem_ras_features_init refined, when CXL components > build as module. > > 5. Optimize callback functions in CXL memory sparing using macros. > etc. > > v12 -> v13: > 1. Changes and Fixes for feedback from Boris > - Function edac_dev_feat_init() merge with edac_dev_register() > - Add macros in EDAC feature specific code for repeated code. > - Correct spelling mistakes. > - Removed feature specific code from the patch "EDAC: Add support > for EDAC device features control" > 2. Changes for feedbacks from Dave Jiang > - Move fields num_features and entries to struct cxl_mailbox, > in "cxl: Add Get Supported Features command for kernel usage" > - Use series from > https://lore.kernel.org/linux-cxl/20240905223711.1990186-1-dave.jiang@intel.com/ > 3. Changes and Fixes for feedback from Ni Fan > - In documentation scrub* to scrubX, ecs_fru* to ecs_fruX > - Corrected some grammar mistakes in the patch headers. > - Fixed an error print for min_scrub_cycle_hrs in the CXL patrol scrub > code. > - Improved an error print in the CXL ECS code. > - bool -> tristate for config CXL_RAS_FEAT > 4. Add support for CXL memory sparing feature. > 5. Add common EDAC memory repair driver for controlling memory repair > features, PPR, memory sparing etc. > > v11 -> v12: > 1. Changes and Fixes for feedback from Boris mainly for > patch "EDAC: Add support for EDAC device features control" > and other generic comments. > > 2. Took CXL patches from Dave Jiang for "Add Get Supported Features > command for kernel usage" and other related patches. Merged helper > functions from this series to the above patch. Modifications of > CXL code in this series due to refactoring of CXL mailbox in Dave's > patches. > > 3. Modified EDAC scrub control code to support multiple scrub instances > per device. > > v10 -> v11: > 1. Feedback from Borislav: > - Add generic EDAC code for control device features to > /drivers/edac/edac_device.c. > - Add common structure in edac for device feature's data. > > 2. Some more optimizations in generic EDAC code for control > device features. > > 3. Changes for feedback from Fan for ACPI RAS2 memory driver. > > 4. Add support for control memory PPR (Post Package Repair) features > in EDAC. > > 5. Add support for maintenance command in the CXL mailbox code, > which is needed for support PPR features in CXL driver. > > 6. Add support for control memory PPR (Post Package Repair) features > and do perform PPR maintenance operation in CXL driver. > > 7. Rename drivers/cxl/core/memscrub.c to drivers/cxl/core/memfeature.c > > v9 -> v10: > 1. Feedback from Mauro Carvalho Chehab: > - Changes suggested in EDAC RAS feature driver. > use uppercase for enums, if else to switch-case, documentation for > static scrub and ecs init functions etc. > - Changes suggested in EDAC scrub. > unit of scrub cycle hour to seconds. > attribute node cycle_in_hours_available to min_cycle_duration and > max_cycle_duration. > attribute node cycle_in_hours to current_cycle_duration. > Use base 0 for kstrtou64() and kstrtol() functions. > etc. > - Changes suggested in EDAC ECS. > uppercase for enums > add ABI documentation. etc > > 2. Feedback from Fan: > - Changes suggested in EDAC RAS feature driver. > use uppercase for enums, change if...else to switch-case. > some optimization in edac_ras_dev_register() function > add missing goto free_ctx > - Changes suggested in the code for feature commands. > - CXL driver scrub and ECS code > use uppercase for enums, fix typo, use enum type for mode > fix lonf lines etc. > > v8 -> v9: > 1. Feedback from Borislav: > - Add scrub control driver to the EDAC on feedback from Borislav. > - Changed DEVICE_ATTR_..() static. > - Changed the write permissions for scrub control sysfs files as > root-only. > 2. Feedback from Fan: > - Optimized cxl_get_feature() function by using min() and removed > feat_out_min_size. > - Removed unreached return from cxl_set_feature() function. > - Changed the term "rate" to "cycle_in_hours" in all the > scrub control code. > - Allow cxl_mem_probe() continue if cxl_mem_patrol_scrub_init() fail, > with just a debug warning. > > 3. Feedback from Jonathan: > - Removed patch __free() based cleanup function for acpi_put_table. > and added fix in the acpi RAS2 driver. > > 4. Feedback from Dan Williams: > - Allow cxl_mem_probe() continue if cxl_mem_patrol_scrub_init() fail, > with just a debug warning. > - Add support for CXL region based scrub control. > > 5. Feedback from Daniel Ferguson on RAS2 drivers: > In the ACPI RAS2 driver, > - Incorporated the changes given for clearing error reported. > - Incorporated the changes given for check the Set RAS Capability > status and return an appropriate error. > In the RAS2 memory driver, > - Added more checks for start/stop bg and on-demand scrubbing > so that addr range in cache do not get cleared and restrict > permitted operations during scrubbing. > > History for v1 to v8 is available here. > https://lore.kernel.org/lkml/20240726160556.2079-1-shiju.jose@huawei.com/ > > Shiju Jose (15): > EDAC: Add support for EDAC device features control > EDAC: Add scrub control feature > EDAC: Add ECS control feature > EDAC: Add memory repair control feature > ACPI:RAS2: Add ACPI RAS2 driver > ras: mem: Add memory ACPI RAS2 driver > cxl: Add helper function to retrieve a feature entry > cxl/memfeature: Add CXL memory device patrol scrub control feature > cxl/memfeature: Add CXL memory device ECS control feature > cxl/mbox: Add support for PERFORM_MAINTENANCE mailbox command > cxl/region: Add helper function to determine memory is online > cxl: Support for finding memory operation attributes from the current > boot > cxl/memfeature: Add CXL memory device soft PPR control feature > EDAC: Update memory repair control interface for memory sparing > feature > cxl/memfeature: Add CXL memory device memory sparing control feature > > Documentation/ABI/testing/sysfs-edac-ecs | 74 + > .../ABI/testing/sysfs-edac-memory-repair | 206 ++ > Documentation/ABI/testing/sysfs-edac-scrub | 69 + > Documentation/edac/features.rst | 104 + > Documentation/edac/index.rst | 12 + > Documentation/edac/memory_repair.rst | 209 ++ > Documentation/edac/scrub.rst | 393 ++++ > drivers/acpi/Kconfig | 11 + > drivers/acpi/Makefile | 1 + > drivers/acpi/ras2.c | 417 ++++ > drivers/cxl/Kconfig | 18 + > drivers/cxl/core/Makefile | 1 + > drivers/cxl/core/core.h | 9 + > drivers/cxl/core/features.c | 21 + > drivers/cxl/core/mbox.c | 45 +- > drivers/cxl/core/memdev.c | 9 + > drivers/cxl/core/memfeature.c | 1723 +++++++++++++++++ > drivers/cxl/core/ras.c | 151 ++ > drivers/cxl/core/region.c | 15 + > drivers/cxl/cxlmem.h | 82 + > drivers/cxl/mem.c | 4 + > drivers/cxl/pci.c | 3 + > drivers/edac/Kconfig | 28 + > drivers/edac/Makefile | 4 + > drivers/edac/ecs.c | 207 ++ > drivers/edac/edac_device.c | 185 ++ > drivers/edac/mem_repair.c | 365 ++++ > drivers/edac/scrub.c | 209 ++ > drivers/ras/Kconfig | 10 + > drivers/ras/Makefile | 1 + > drivers/ras/acpi_ras2.c | 383 ++++ > include/acpi/ras2_acpi.h | 47 + > include/cxl/features.h | 2 + > include/linux/edac.h | 228 +++ > 34 files changed, 5244 insertions(+), 2 deletions(-) > create mode 100644 Documentation/ABI/testing/sysfs-edac-ecs > create mode 100644 Documentation/ABI/testing/sysfs-edac-memory-repair > create mode 100644 Documentation/ABI/testing/sysfs-edac-scrub > create mode 100644 Documentation/edac/features.rst > create mode 100644 Documentation/edac/index.rst > create mode 100644 Documentation/edac/memory_repair.rst > create mode 100644 Documentation/edac/scrub.rst > create mode 100755 drivers/acpi/ras2.c > create mode 100644 drivers/cxl/core/memfeature.c > create mode 100644 drivers/cxl/core/ras.c > create mode 100755 drivers/edac/ecs.c > create mode 100755 drivers/edac/mem_repair.c > create mode 100755 drivers/edac/scrub.c > create mode 100644 drivers/ras/acpi_ras2.c > create mode 100644 include/acpi/ras2_acpi.h > > -- > 2.43.0 > -- Fan Ni
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