VM66144: HMC EXCEPTION AFTER SET MT 1 WITH PARKED PROCESSORS

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Dynamic SMT thread deactivation of parked processor does not
  stop processor after loading disabled wait 9003.
  This causes the HMC to report an exception condition even
  though there is no hardware or software malfunction.
  

Local fix

• N/A
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: Customers using SET MT command.              *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  ****************************************************************
  * RECOMMENDATION: APPLY PTF                                    *
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  The 9003 disabled wait state is a normal indication that a
  processor has been quiesced due to a request by the system.
  In an SMT-enabled environment, the HMC considers it to be
  an exception case when a core with an operating thread 0
  processor has a thread 1 processor that is in a disabled
  wait state and is not stopped.
  When the SET MT command is used to switch from SMT-2 to SMT-1,
  all thread 1 processors are deactivated and load the 9003
  disabled wait state.  After the processors on the unparked
  processors load the 9003 disabled wait state, the Master
  processor issues a SIGP CPU-Reset to them which places them in
  the stopped state.  However, this is not done to processors
  on parked cores.  As a result they remain in the operating
  state with a disabled wait state PSW.  This condition is what
  misleads the HMC into reporting the exception condition.
  
  A partition marked as having an exception condition due to
  this problem can be identified by:
  1.  Q MT shows that SMT is enabled, but the IFLs are running
      with only 1 thread activated.
  2.  Q PROC TOPO shows that some cores are parked.
  3.  The SE shows the processors with the exception condition
      have disabled wait 9003, are not stopped, have odd
      processor addresses, and are on the parked cores.
  

Problem conclusion

• HCPMPC (OCO) was updated.
  

Temporary fix

• FOR RELEASE VM/ESA CP/ESA R640 :
  PREREQ: VM65988
  CO-REQ: NONE
  IF-REQ: NONE
  

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UM35301

Modules/Macros

• HCPMPC
  

Fix information

• Fixed component name

  VM CP

• Fixed component ID

  568411202

Applicable component levels

• R640 PSY UM35301

     UP18/12/14 P 1802

Fix is available

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