Re: [PATCH v10 6/6] powerpc/papr_scm: Implement support for PAPR_PDSM_HEALTH

Vaibhav Jain
2020-06-06T12:35:01Z

Ira Weiny <ira.weiny@intel.com> writes:

> On Fri, Jun 05, 2020 at 05:11:36AM +0530, Vaibhav Jain wrote:
>> This patch implements support for PDSM request 'PAPR_PDSM_HEALTH'
>> that returns a newly introduced 'struct nd_papr_pdsm_health' instance
>> containing dimm health information back to user space in response to
>> ND_CMD_CALL. This functionality is implemented in newly introduced
>> papr_pdsm_health() that queries the nvdimm health information and
>> then copies this information to the package payload whose layout is
>> defined by 'struct nd_papr_pdsm_health'.
>>
>> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
>> Cc: Dan Williams <dan.j.williams@intel.com>
>> Cc: Michael Ellerman <mpe@ellerman.id.au>
>> Cc: Ira Weiny <ira.weiny@intel.com>
>> Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
>> ---
>> Changelog:
>>
>> v9..v10:
>> * Removed code in papr_pdsm_health that performed validation on pdsm
>> payload version and corrosponding struct and defines used for
>> validation of payload version.
>> * Dropped usage of struct papr_pdsm_health in 'struct
>> papr_scm_priv'. Instead papr_psdm_health() now uses
>> 'papr_scm_priv.health_bitmap' to populate the pdsm payload.
>> * Above change also fixes the problem where this patch was removing
>> the code that was previously introduced in this patch-series.
>> [ Ira ]
>> * Introduced a new def ND_PDSM_ENVELOPE_HDR_SIZE that indicates the
>> space allocated to 'struct nd_pdsm_cmd_pkg' fields except 'struct
>> nd_cmd_pkg'. This def is useful in validating payload sizes.
>> * Reworked papr_pdsm_health() to enforce a specific payload size for
>> 'PAPR_PDSM_HEALTH' pdsm request.
>>
>> Resend:
>> * Added ack from Aneesh.
>>
>> v8..v9:
>> * s/PAPR_SCM_PDSM_HEALTH/PAPR_PDSM_HEALTH/g [ Dan , Aneesh ]
>> * s/PAPR_SCM_PSDM_DIMM_*/PAPR_PDSM_DIMM_*/g
>> * Renamed papr_scm_get_health() to papr_psdm_health()
>> * Updated patch description to replace papr-scm dimm with nvdimm.
>>
>> v7..v8:
>> * None
>>
>> Resend:
>> * None
>>
>> v6..v7:
>> * Updated flags_show() to use seq_buf_printf(). [Mpe]
>> * Updated papr_scm_get_health() to use newly introduced
>> __drc_pmem_query_health() bypassing the cache [Mpe].
>>
>> v5..v6:
>> * Added attribute '__packed' to 'struct nd_papr_pdsm_health_v1' to
>> gaurd against possibility of different compilers adding different
>> paddings to the struct [ Dan Williams ]
>>
>> * Updated 'struct nd_papr_pdsm_health_v1' to use __u8 instead of
>> 'bool' and also updated drc_pmem_query_health() to take this into
>> account. [ Dan Williams ]
>>
>> v4..v5:
>> * None
>>
>> v3..v4:
>> * Call the DSM_PAPR_SCM_HEALTH service function from
>> papr_scm_service_dsm() instead of papr_scm_ndctl(). [Aneesh]
>>
>> v2..v3:
>> * Updated struct nd_papr_scm_dimm_health_stat_v1 to use '__xx' types
>> as its exported to the userspace [Aneesh]
>> * Changed the constants DSM_PAPR_SCM_DIMM_XX indicating dimm health
>> from enum to #defines [Aneesh]
>>
>> v1..v2:
>> * New patch in the series
>> ---
>> arch/powerpc/include/uapi/asm/papr_pdsm.h | 33 +++++++++++
>> arch/powerpc/platforms/pseries/papr_scm.c | 70 +++++++++++++++++++++++
>> 2 files changed, 103 insertions(+)
>>
>> diff --git a/arch/powerpc/include/uapi/asm/papr_pdsm.h b/arch/powerpc/include/uapi/asm/papr_pdsm.h
>> index 8b1a4f8fa316..c4c990ede5d4 100644
>> --- a/arch/powerpc/include/uapi/asm/papr_pdsm.h
>> +++ b/arch/powerpc/include/uapi/asm/papr_pdsm.h
>> @@ -71,12 +71,17 @@ struct nd_pdsm_cmd_pkg {
>> __u8 payload[]; /* In/Out: Sub-cmd data buffer */
>> } __packed;
>>
>> +/* Calculate size used by the pdsm header fields minus 'struct nd_cmd_pkg' */
>> +#define ND_PDSM_ENVELOPE_HDR_SIZE \
>> + (sizeof(struct nd_pdsm_cmd_pkg) - sizeof(struct nd_cmd_pkg))
>> +
[ ]
>
> This is kind of a weird name for this.
>
> Isn't this just the ND PDSM header size? What is 'envelope' mean
> here?
Was referring to 'nd_cmd_pkg' envelop here. But yes removing 'ENVELOPE'
should make it more concise. Have already done this in v11 of this patch.

>
>> /*
>> * Methods to be embedded in ND_CMD_CALL request. These are sent to the kernel
>> * via 'nd_pdsm_cmd_pkg.hdr.nd_command' member of the ioctl struct
>> */
>> enum papr_pdsm {
>> PAPR_PDSM_MIN = 0x0,
>> + PAPR_PDSM_HEALTH,
>> PAPR_PDSM_MAX,
>> };
>>
>> @@ -95,4 +100,32 @@ static inline void *pdsm_cmd_to_payload(struct nd_pdsm_cmd_pkg *pcmd)
>> return (void *)(pcmd->payload);
>> }
>>
>> +/* Various nvdimm health indicators */
>> +#define PAPR_PDSM_DIMM_HEALTHY 0
>> +#define PAPR_PDSM_DIMM_UNHEALTHY 1
>> +#define PAPR_PDSM_DIMM_CRITICAL 2
>> +#define PAPR_PDSM_DIMM_FATAL 3
>> +
>> +/*
>> + * Struct exchanged between kernel & ndctl in for PAPR_PDSM_HEALTH
>> + * Various flags indicate the health status of the dimm.
>> + *
>> + * dimm_unarmed : Dimm not armed. So contents wont persist.
>> + * dimm_bad_shutdown : Previous shutdown did not persist contents.
>> + * dimm_bad_restore : Contents from previous shutdown werent restored.
>> + * dimm_scrubbed : Contents of the dimm have been scrubbed.
>> + * dimm_locked : Contents of the dimm cant be modified until CEC reboot
>> + * dimm_encrypted : Contents of dimm are encrypted.
>> + * dimm_health : Dimm health indicator. One of PAPR_PDSM_DIMM_XXXX
>> + */
>> +struct nd_papr_pdsm_health {
>> + __u8 dimm_unarmed;
>> + __u8 dimm_bad_shutdown;
>> + __u8 dimm_bad_restore;
>> + __u8 dimm_scrubbed;
>> + __u8 dimm_locked;
>> + __u8 dimm_encrypted;
>> + __u16 dimm_health;
>> +} __packed;
>> +
>> #endif /* _UAPI_ASM_POWERPC_PAPR_PDSM_H_ */
>> diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
>> index 05eb56ecab5e..984942be24c1 100644
>> --- a/arch/powerpc/platforms/pseries/papr_scm.c
>> +++ b/arch/powerpc/platforms/pseries/papr_scm.c
>> @@ -421,6 +421,72 @@ static int is_cmd_valid(struct nvdimm *nvdimm, unsigned int cmd, void *buf,
>> return 0;
>> }
>>
>> +/* Fetch the DIMM health info and populate it in provided package. */
>> +static int papr_pdsm_health(struct papr_scm_priv *p,
>> + struct nd_pdsm_cmd_pkg *pkg)
>> +{
>> + int rc;
>> + struct nd_papr_pdsm_health health = { 0 };
>> + u16 copysize = sizeof(struct nd_papr_pdsm_health);
>> + u16 payload_size = pkg->hdr.nd_size_out - ND_PDSM_ENVELOPE_HDR_SIZE;
>> +
>> + /* Ensure correct payload size that can hold struct nd_papr_pdsm_health */
>> + if (payload_size != copysize) {
>> + dev_dbg(&p->pdev->dev,
>> + "Unexpected payload-size (%u). Expected (%u)",
>> + pkg->hdr.nd_size_out, copysize);
>> + rc = -ENOSPC;
>> + goto out;
>> + }
>> +
>> + /* Ensure dimm health mutex is taken preventing concurrent access */
>> + rc = mutex_lock_interruptible(&p->health_mutex);
>> + if (rc)
>> + goto out;
>> +
>> + /* Always fetch upto date dimm health data ignoring cached values */
>> + rc = __drc_pmem_query_health(p);
>> + if (rc) {
>> + mutex_unlock(&p->health_mutex);
>> + goto out;
>> + }
>> +
>> + /* update health struct with various flags derived from health bitmap */
>> + health = (struct nd_papr_pdsm_health) {
>> + .dimm_unarmed = p->health_bitmap & PAPR_PMEM_UNARMED_MASK,
>> + .dimm_bad_shutdown = p->health_bitmap & PAPR_PMEM_BAD_SHUTDOWN_MASK,
>> + .dimm_bad_restore = p->health_bitmap & PAPR_PMEM_BAD_RESTORE_MASK,
>> + .dimm_encrypted = p->health_bitmap & PAPR_PMEM_ENCRYPTED,
>> + .dimm_locked = p->health_bitmap & PAPR_PMEM_SCRUBBED_AND_LOCKED,
>> + .dimm_scrubbed = p->health_bitmap & PAPR_PMEM_SCRUBBED_AND_LOCKED,
>
> Are you sure these work? These are not assignments to a bool so I don't think
> gcc will do what you want here.
Yeah, somehow this slipped by and didnt show up in my tests. I checked
the assembly dump and seems GCC was silently skipping initializing these
fields without making any noise. Have rectified this in v11 by changing
these designated initilizers to

.dimm_locked = !!(p->health_bitmap & PAPR_PMEM_SCRUBBED_AND_LOCKED)

Thanks for catching this.

~ Vaibhav
>
> Ira
>
>> + .dimm_health = PAPR_PDSM_DIMM_HEALTHY,
>> + };
>> +
>> + /* Update field dimm_health based on health_bitmap flags */
>> + if (p->health_bitmap & PAPR_PMEM_HEALTH_FATAL)
>> + health.dimm_health = PAPR_PDSM_DIMM_FATAL;
>> + else if (p->health_bitmap & PAPR_PMEM_HEALTH_CRITICAL)
>> + health.dimm_health = PAPR_PDSM_DIMM_CRITICAL;
>> + else if (p->health_bitmap & PAPR_PMEM_HEALTH_UNHEALTHY)
>> + health.dimm_health = PAPR_PDSM_DIMM_UNHEALTHY;
>> +
>> + /* struct populated hence can release the mutex now */
>> + mutex_unlock(&p->health_mutex);
>> +
>> + dev_dbg(&p->pdev->dev, "Copying payload size=%u\n", copysize);
>> +
>> + /* Copy the health struct to the payload */
>> + memcpy(pdsm_cmd_to_payload(pkg), &health, copysize);
>> +
>> + /* Update fw size including size of struct nd_pdsm_cmd_pkg fields */
>> + pkg->hdr.nd_fw_size = copysize + ND_PDSM_ENVELOPE_HDR_SIZE;
>> +
>> +out:
>> + dev_dbg(&p->pdev->dev, "completion code = %d\n", rc);
>> +
>> + return rc;
>> +}
>> +
>> /*
>> * For a given pdsm request call an appropriate service function.
>> * Note: Use 'nd_pdsm_cmd_pkg.cmd_status to report psdm servicing errors. Hence
>> @@ -435,6 +501,10 @@ static void papr_scm_service_pdsm(struct papr_scm_priv *p,
>>
>> /* Call pdsm service function */
>> switch (pdsm) {
>> + case PAPR_PDSM_HEALTH:
>> + pkg->cmd_status = papr_pdsm_health(p, pkg);
>> + break;
>> +
>> default:
>> dev_dbg(&p->pdev->dev, "PDSM[0x%x]: Unsupported PDSM request\n",
>> pdsm);
>> --
>> 2.26.2
>>

--
Cheers
~ Vaibhav