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

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@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