[PATCH v2] powerpc/papr_scm: Reduce error severity if nvdimm stats inaccessible

[Ira Weiny]

On Thu, May 06, 2021 at 12:46:06AM +0530, Vaibhav Jain wrote:
> Currently drc_pmem_qeury_stats() generates a dev_err in case
> "Enable Performance Information Collection" feature is disabled from
> HMC or performance stats are not available for an nvdimm. The error is
> of the form below:
> 
> papr_scm ibm,persistent-memory:ibm,pmemory at 44104001: Failed to query
> 	 performance stats, Err:-10
> 
> This error message confuses users as it implies a possible problem
> with the nvdimm even though its due to a disabled/unavailable
> feature. We fix this by explicitly handling the H_AUTHORITY and
> H_UNSUPPORTED errors from the H_SCM_PERFORMANCE_STATS hcall.
> 
> In case of H_AUTHORITY error an info message is logged instead of an
> error, saying that "Permission denied while accessing performance
> stats". Also '-EACCES' error is return instead of -EPERM.

I thought you clarified before that this was a permission issue.  So why change
the error to EACCES?

> 
> In case of H_UNSUPPORTED error we return a -EPERM error back from
> drc_pmem_query_stats() indicating that performance stats-query
> operation is not supported on this nvdimm.

EPERM seems wrong here too...  ENOTSUP?

Ira