Subject: Re: [PATCH v6 0/4] powerpc/papr_scm: Add support for reporting nvdimm health

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Wed, 29 Apr 2020 13:49:27 +0530

Vaibhav Jain <[email-masked]> writes:

> The PAPR standard[1][3] provides mechanisms to query the health and
> performance stats of an NVDIMM via various hcalls as described in
> Ref[2].  Until now these stats were never available nor exposed to the
> user-space tools like 'ndctl'. This is partly due to PAPR platform not
> having support for ACPI and NFIT. Hence 'ndctl' is unable to query and
> report the dimm health status and a user had no way to determine the
> current health status of a NDVIMM.
>
> To overcome this limitation, this patch-set updates papr_scm kernel
> module to query and fetch nvdimm health stats using hcalls described
> in Ref[2].  This health and performance stats are then exposed to
> userspace via syfs and PAPR-nvDimm-Specific-Methods(PDSM) issued by
> libndctl.
>
> These changes coupled with proposed ndtcl changes located at Ref[4]
> should provide a way for the user to retrieve NVDIMM health status
> using ndtcl.
>
> Below is a sample output using proposed kernel + ndctl for PAPR NVDIMM
> in a emulation environment:
>
>  # ndctl list -DH
> [
>   {
>     "dev":"nmem0",
>     "health":{
>       "health_state":"fatal",
>       "shutdown_state":"dirty"
>     }
>   }
> ]
>
> Dimm health report output on a pseries guest lpar with vPMEM or HMS
> based nvdimms that are in perfectly healthy conditions:
>
>  # ndctl list -d nmem0 -H
> [
>   {
>     "dev":"nmem0",
>     "health":{
>       "health_state":"ok",
>       "shutdown_state":"clean"
>     }
>   }
> ]
>
> PAPR nvDimm-Specific-Methods(PDSM)
> ==================================
>
> PDSM requests are issued by vendor specific code in libndctl to
> execute certain operations or fetch information from NVDIMMS. PDSMs
> requests can be sent to papr_scm module via libndctl(userspace) and
> libnvdimm (kernel) using the ND_CMD_CALL ioctl command which can be
> handled in the dimm control function papr_scm_ndctl(). Current
> patchset proposes a single PDSM to retrieve NVDIMM health, defined in
> the newly introduced uapi header named 'papr_scm_pdsm.h'. Support for
> more PDSMs will be added in future.
>
> Structure of the patch-set
> ==========================
>
> The patchset starts with implementing support for fetching nvdimm health
> information from PHYP and partially exposing it to user-space via a nvdimm
> sysfs flag.
>
> Second & Third patches deal with implementing support for servicing PDSM
> commands in papr_scm module.
>
> Finally the Fourth patch implements support for servicing PDSM
> 'PAPR_SCM_PDSM_HEALTH' that returns the nvdimm health information to
> libndctl.

You can add to the series.

Reviewed-by: Aneesh Kumar K.V <[email-masked]>

-aneesh