linux-nvdimm.lists.01.org archive mirror
 help / color / mirror / Atom feed
From: Vaibhav Jain <vaibhav@linux.ibm.com>
To: Ira Weiny <ira.weiny@intel.com>
Cc: linux-nvdimm@lists.01.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc/papr_scm: Reduce error severity if nvdimm stats inaccessible
Date: Thu, 15 Apr 2021 17:18:11 +0530	[thread overview]
Message-ID: <87h7k7lqf8.fsf@vajain21.in.ibm.com> (raw)
In-Reply-To: <20210414212417.GC1904484@iweiny-DESK2.sc.intel.com>

Ira Weiny <ira.weiny@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.weiny@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 <vaibhav@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
_______________________________________________
Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
To unsubscribe send an email to linux-nvdimm-leave@lists.01.org

  reply	other threads:[~2021-04-15 11:48 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-14 12:40 [PATCH] powerpc/papr_scm: Reduce error severity if nvdimm stats inaccessible Vaibhav Jain
2021-04-14 15:36 ` Ira Weiny
2021-04-14 16:21   ` Vaibhav Jain
2021-04-14 21:24     ` Ira Weiny
2021-04-15 11:48       ` Vaibhav Jain [this message]
2021-04-18  7:58         ` kajoljain
2021-04-14 21:32 ` Dan Williams
2021-04-15 11:43   ` Vaibhav Jain
2021-04-15 17:03     ` Dan Williams

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=87h7k7lqf8.fsf@vajain21.in.ibm.com \
    --to=vaibhav@linux.ibm.com \
    --cc=ira.weiny@intel.com \
    --cc=linux-nvdimm@lists.01.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).