Bug 1360533

(In reply to yalzhang from comment #0)
> Description of problem:
> When enable mbmt/mbml on a host didn't support mbm, the error message need
> to be more clear.
> 
> Version-Release number of selected component (if applicable):
> libvirt-2.0.0-3.el7.x86_64
> 
> How reproducible:
> 100%
> 
> Steps to Reproduce:
> 1.Prepare a host with intel E5-2600 series v2 cpu which do not support intel
> mbm but support cmt.
 
Correct a typo here, it should be **v3** not v2.(v3 just support cmt, and v4 support cmt and mbml/mbmt)

Some more scenarios about error message issue. 

Test with libvirt-2.0.0-3.el7.x86_64 and intel E5-2640 v4 cpu.
 
1.When disable some event which is already disabled, it will report error.

# virsh start rhel7.2
Domain rhel7.2 started

# virsh perf rhel7.2
cmt            : disabled
mbmt           : disabled
mbml           : disabled

# virsh perf rhel7.2 --disable cmt
error: Unable to enable/disable perf events
error: Unable to disable perf event type=0: Bad file descriptor

# virsh perf rhel7.2 --disable mbmt
error: Unable to enable/disable perf events
error: Unable to disable perf event type=1: Bad file descriptor

# virsh perf rhel7.2 --disable mbml
error: Unable to enable/disable perf events
error: Unable to disable perf event type=2: Bad file descriptor

2. When combine enable and disable, the same error will occur, but in fact the "--enable" part succeed.

# virsh start rhel7.2
Domain rhel7.2 started

# virsh perf rhel7.2
cmt            : disabled
mbmt           : disabled
mbml           : disabled

# virsh perf rhel7.2 --enable mbmt --disable cmt
error: Unable to enable/disable perf events
error: Unable to disable perf event type=0: Bad file descriptor

# virsh perf rhel7.2
cmt            : disabled
mbmt           : enabled
mbml           : disabled

Actual results:
step 1 and 2, unexpected error occur.

Expected results:
when disable the event which is already disabled, it should not report error, ignore the error message is OK.

Additional info:
Enable the one which is already enabled works fine and no error occur. 
The guest is running:
# virsh perf rhel7.2
cmt            : enabled
mbmt           : enabled
mbml           : disabled

# virsh perf rhel7.2 --enable cmt,mbmt

# virsh perf rhel7.2
cmt            : enabled
mbmt           : enabled
mbml           : disabled

There's been changes made upstream that alter the error messages seen...

1. From Description: 

error: Unable to open perf type=26 for pid=24570: Invalid argument

has been altered to be:

Unable to open perf event for %s

where %s would be "cmt", "mbmt", or "mbml"

I suppose "for host CPU" could be added

This was done by: 
commit b00d7f298b7dd57d923bc9a9a6df47471e4eaab8
Author: Qiaowei Ren <qiaowei.ren>
Date:   Wed Aug 3 13:23:31 2016 -0400

    perf: Adjust the perf initialization
    
    Introduce a static attr table and refactor virPerfEventEnable() for
    general purpose usage.
    
    This patch creates a static table/matrix that converts the VIR_PERF_EVENT_*
    events into their respective "attr.type" and "attr.config" so that
    virPerfEventEnable doesn't have the switch the calling function passes
    by value the 'type'.
    
    Signed-off-by: Qiaowei Ren <qiaowei.ren>

-=-=-=-=-=-=

2. From comment 3

virsh perf rhel7.2 --disable {cmt|mbmt|mbml}

still results in the same error.  This should be fixed.

----

virsh perf rhel7.2 --enable mbmt --disable cmt

No longer enables mbmt, it gives an error :

virsh perf $dom --enable mbmt --disable cmt
error: Unable to enable/disable perf events
error: argument unsupported: unable to enable perf event for mbmt

----

Patches sent to resolve the disable the disabled error... Especially on systems that don't support it!

Also added a "host cpu" clarification to error messages and used the perf name in the disable failure message rather than the number (since other messages already were altered anyway).

http://www.redhat.com/archives/libvir-list/2016-October/msg00319.html

Patches pushed:

commit 0f3f8ac97efed4a5c574e6b51e356cea2f825fcf
Author: John Ferlan <jferlan>
Date:   Fri Oct 7 08:28:58 2016 -0400

    util: Check/ignore already disabled event
    
    If the event is already disabled, then don't bother with setting it
    disabled again.  Causes unnecessary error on systems that don't support
    the feature anyway.
...


$ git describe 0f3f8ac97efed4a5c574e6b51e356cea2f825fcf
v2.3.0-40-g0f3f8ac

Test passed with version libvirt-2.5.0-1.el7.x86_64.
1.In a host which doesn't support "cmt"/"mbmt"/"mbml", when the guest rhel7_perf_test is active / inactive, run below command, it returns expected error message.
   
   #virsh perf rhel7_perf_test  --enable cmt
   error: Unable to enable/disable perf events
   error: argument unsupported: unable to enable host cpu perf event for cmt


2. In a host which doesn't support "cmt"/"mbmt"/"mbml".
   #virsh perf rhel7_perf_test
    cmt                 :disabled
    mbmt                :disabled
    mbml                :disabled
    cpu_cycles          :disabled
    instructions        :disabled
    cache_references    :disabled
    cache_misses        :disabled


   #virsh perf rhel7_perf_test --disable "cmt"

   No any message returned.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHEA-2017:1846

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHEA-2017:1846