Ira Weiny <ira.we...@intel.com> writes: > On Wed, Apr 14, 2021 at 09:51:40PM +0530, Vaibhav Jain wrote: >> Thanks for looking into this patch Ira, >> >> Ira Weiny <ira.we...@intel.com> writes: >> >> > On Wed, Apr 14, 2021 at 06:10:26PM +0530, Vaibhav Jain wrote: >> >> Currently drc_pmem_qeury_stats() generates a dev_err in case >> >> "Enable Performance Information Collection" feature is disabled from >> >> HMC. 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 feature. >> >> >> >> So we fix this by explicitly handling the H_AUTHORITY error from the >> >> H_SCM_PERFORMANCE_STATS hcall and generating a warning instead of an >> >> error, saying that "Performance stats in-accessible". >> >> >> >> Fixes: 2d02bf835e57('powerpc/papr_scm: Fetch nvdimm performance stats >> >> from PHYP') >> >> Signed-off-by: Vaibhav Jain <vaib...@linux.ibm.com> >> >> --- >> >> arch/powerpc/platforms/pseries/papr_scm.c | 3 +++ >> >> 1 file changed, 3 insertions(+) >> >> >> >> diff --git a/arch/powerpc/platforms/pseries/papr_scm.c >> >> b/arch/powerpc/platforms/pseries/papr_scm.c >> >> index 835163f54244..9216424f8be3 100644 >> >> --- a/arch/powerpc/platforms/pseries/papr_scm.c >> >> +++ b/arch/powerpc/platforms/pseries/papr_scm.c >> >> @@ -277,6 +277,9 @@ static ssize_t drc_pmem_query_stats(struct >> >> papr_scm_priv *p, >> >> dev_err(&p->pdev->dev, >> >> "Unknown performance stats, Err:0x%016lX\n", ret[0]); >> >> return -ENOENT; >> >> + } else if (rc == H_AUTHORITY) { >> >> + dev_warn(&p->pdev->dev, "Performance stats in-accessible"); >> >> + return -EPERM; >> > >> > Is this because of a disabled feature or because of permissions? >> >> Its because of a disabled feature that revokes permission for a guest to >> retrieve performance statistics. >> >> The feature is called "Enable Performance Information Collection" and >> once disabled the hcall H_SCM_PERFORMANCE_STATS returns an error >> H_AUTHORITY indicating that the guest doesn't have permission to retrieve >> performance statistics. > > In that case would it be appropriate to have the error message indicate a > permission issue? > > Something like 'permission denied'?
Yes, Something like "Permission denied while accessing performance stats" might be more clear and intuitive. Will update the warn message in v2. > > Ira > -- Cheers ~ Vaibhav