A fix is available
APAR status
Closed as program error.
Error description
If a guest uses any of the CANCEL Pending Page Release functionality, diagnose x'214' subcode x'01, x'02', or x'03' a page of data could unexpectedly be reverted to zeros.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All users using DIAGNOSE X'214' * * subcodes x'01', x'02, or x'03' * * Cancel Pending Page Release, CPR, * * Cancel All Pending Releases, CAPR, * * Cancel Pending Release and Validate, * * CPRV. * **************************************************************** * PROBLEM DESCRIPTION: * **************************************************************** * RECOMMENDATION: APPLY PTF * **************************************************************** Guests that use any form of Pending Page Release Cancel function, Diagnose x'214' subcode x'01', x'02, or x'03' can randomly have a page of storage zeroed. This can lead to guest ABENDS and incorrect processing.
Problem conclusion
Pending Page Release uses a buffer to hold the address of the guest pages pending release. Pointers are used to manipulate the contents of the buffer and point to the next available slot to put a pending page to be released in. The list is maintained in order from low storage to high storage. It is possible for a guest to Cancel a Pending Page Release. A Cancel Pending Page Release manipulates the pointer and contents of the buffer so that either a page or range of pages are not removed from guest storage. When CP decides to purge the table all entries in the table are purged. In this particular case there was one page in the Pending Purge Buffer, followed by cancel Pending Page Release, the pointers were adjusted to point to the begininning of the buffer, but the entry remained. When Purge was initiated the contents of the buffer was purged. Purging the contents caused the next reference of the page to be reinstantiated. HCPPPR was updated to determine if it was already pointing to the beginning of the buffer prior to purging the contents, therefore preventing the page from being zeroed.
Temporary fix
********* * HIPER * ********* FOR RELEASE VM/ESA CP/ESA R640 : PREREQ: NONE CO-REQ: NONE IF-REQ: NONE FOR RELEASE VM/ESACP/ESAR710 : PREREQ: NONE CO-REQ: NONE IF-REQ: NONE
Comments
APAR Information
APAR number
VM65933
Reported component name
VM CMS
Reported component ID
568411201
Reported release
640
Status
CLOSED PER
PE
NoPE
HIPER
YesHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2019-08-08
Closed date
2020-01-21
Last modified date
2021-06-29
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UM35488 UM35494
Modules/Macros
HCPPPR
Fix information
Fixed component name
VM CP
Fixed component ID
568411202
Applicable component levels
Fix is available
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Document Information
Modified date:
30 June 2021