[PATCH v3] powerpc/papr_scm: Reduce error severity if nvdimm stats inaccessible

Discussion:

Vaibhav Jain

2021-05-08 04:36:42 UTC

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,***@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" and an EPERM error is returned back.

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

Fixes: 2d02bf835e57('powerpc/papr_scm: Fetch nvdimm performance stats from PHYP')
Signed-off-by: Vaibhav Jain <***@linux.ibm.com>
---
Changelog

v3:
* Return EOPNOTSUPP error in case of H_UNSUPPORTED [ Ira ]
* Return EPERM in case of H_AUTHORITY [ Ira ]
* Updated patch description

v2:
* Updated the message logged in case of H_AUTHORITY error [ Ira ]
* Switched from dev_warn to dev_info in case of H_AUTHORITY error.
* Instead of -EPERM return -EACCESS for H_AUTHORITY error.
* Added explicit handling of H_UNSUPPORTED error.
---
arch/powerpc/platforms/pseries/papr_scm.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
index ef26fe40efb0..e2b69cc3beaf 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -310,6 +310,13 @@ 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_info(&p->pdev->dev,
+ "Permission denied while accessing performance stats");
+ return -EPERM;
+ } else if (rc == H_UNSUPPORTED) {
+ dev_dbg(&p->pdev->dev, "Performance stats unsupported\n");
+ return -EOPNOTSUPP;
} else if (rc != H_SUCCESS) {
dev_err(&p->pdev->dev,
"Failed to query performance stats, Err:%lld\n", rc);

--
2.31.1

Ira Weiny

2021-05-08 15:11:30 UTC

Permalink

Post by Vaibhav Jain
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
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" and an EPERM error is returned back.
In case of H_UNSUPPORTED error we return a EOPNOTSUPP error back from
drc_pmem_query_stats() indicating that performance stats-query
operation is not supported on this nvdimm.
Fixes: 2d02bf835e57('powerpc/papr_scm: Fetch nvdimm performance stats from PHYP')
---
Changelog
* Return EOPNOTSUPP error in case of H_UNSUPPORTED [ Ira ]
* Return EPERM in case of H_AUTHORITY [ Ira ]
* Updated patch description
* Updated the message logged in case of H_AUTHORITY error [ Ira ]
* Switched from dev_warn to dev_info in case of H_AUTHORITY error.
* Instead of -EPERM return -EACCESS for H_AUTHORITY error.
* Added explicit handling of H_UNSUPPORTED error.
---
arch/powerpc/platforms/pseries/papr_scm.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
index ef26fe40efb0..e2b69cc3beaf 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -310,6 +310,13 @@ 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_info(&p->pdev->dev,
+ "Permission denied while accessing performance stats");
+ return -EPERM;
+ } else if (rc == H_UNSUPPORTED) {
+ dev_dbg(&p->pdev->dev, "Performance stats unsupported\n");
+ return -EOPNOTSUPP;
} else if (rc != H_SUCCESS) {
dev_err(&p->pdev->dev,
"Failed to query performance stats, Err:%lld\n", rc);
--
2.31.1

kajoljain

2021-05-19 07:06:45 UTC

Permalink

Patch looks good to me.

Reviewed-By: Kajol Jain<***@linux.ibm.com>

Thanks,
Kajol Jain

Post by Vaibhav Jain
* Updated the message logged in case of H_AUTHORITY error [ Ira ]
* Switched from dev_warn to dev_info in case of H_AUTHORITY error.
* Instead of -EPERM return -EACCESS for H_AUTHORITY error.
* Added explicit handling of H_UNSUPPORTED error.
---
arch/powerpc/platforms/pseries/papr_scm.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
index ef26fe40efb0..e2b69cc3beaf 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -310,6 +310,13 @@ 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_info(&p->pdev->dev,
+ "Permission denied while accessing performance stats");
+ return -EPERM;
+ } else if (rc == H_UNSUPPORTED) {
+ dev_dbg(&p->pdev->dev, "Performance stats unsupported\n");
+ return -EOPNOTSUPP;
} else if (rc != H_SUCCESS) {
dev_err(&p->pdev->dev,
"Failed to query performance stats, Err:%lld\n", rc);

Michael Ellerman

2021-06-06 12:08:35 UTC

Permalink

Applied to powerpc/next.

[1/1] powerpc/papr_scm: Reduce error severity if nvdimm stats inaccessible
https://git.kernel.org/powerpc/c/f3f6d18417eb44ef393b23570d384d2778ef22dc

cheers