A fix is available
APAR status
Closed as program error.
Error description
This is Feature Pack 03 Fix Pack 05 for z/VM 7.4.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All users exploiting: * * - The z/VM Virtual Switch * * - EQDIO Virtual NICs * * - EQDIO adapters * * - QDIO adapters * **************************************************************** * PROBLEM DESCRIPTION: * **************************************************************** * RECOMMENDATION: APPLY PTF * **************************************************************** The following issues are addressed by this APAR: OSH SET VSWITCH SWITCHOVER loses connectivity when there are 2 backup RDEVs --------------------------------------------------------------- When there are more than one backup RDEVs available in a traditional OSH VSWITCH, a SET VSWITCH SWITCHOVER command (with or without specifying an RDEV) appears successful, but connectivity is lost. The EQID of an EQDIO device is reset after a config off/on ---------------------------------------------------------- When performing a config off/on of an EQDIO device associated with a VSWITCH or a LAG group, the EQID of the device is cleared. VSWITCH error recovery message indicates a "persistent error condition" which results in a recovery loop ------------------------------------------------------ Persistent errors are meant to require operator intervention (SET VSWITCH CONNECT) when the problem has cleared. OSH VSWITCH support is still attempting to automatically recover devices that have encountered a persistent error, which leads to a recovery loop and many messages on the operator console. Additional monitor counters are needed for QDIO/EQDIO ----------------------------------------------------- Monitor records do not currently provide sufficient counters for performing performance comparisons between QDIO and EQDIO devices. z/OS guest receives error code 03 when deactivating EQDIO virtual NICs ------------------------------------------------------------ When a z/OS guest deactivates an EQDIO virtual NIC, it can receive message HCPSWU2831E indicating there was a controller error code 03 encountered. Aside from the message, there are no noticable symptoms. Eliminate unnecessary EQDIO instructions to improve efficiency -------------------------------------------------------------- Performance analysis has shown that some relatively high cost EQDIO instructions are issued more frequently than required. Unexpected ISOLATE message when a switch port is enabled for LAG ---------------------------------------------------------------- In a multi-port EQDIO LAG, if multiple ports are shutdown and then one is re-enabled, the VSWITCH support will encounter a message indicating a protocol violation because the EQDIO device is not in the correct state to issue an ISOLATE command. This occurs when the VSWITCH is not configured for isolation. LAG EQDIO VSWITCH does not attempt to initialize other devices if first device is disabled -------------------------------------------------------------- When multiple EQDIO devices are configured in a link aggregation group, and one or more of those devices is offline when a VSWITCH using that group is brought online, device initialization will stop once it encounters the first disabled device. This means that in a LAG group with three devices where the first device is offline, no devices will complete initialization and there will be no connectivity. EQDIO VSWITCH loses connectivity for some guests after a hardware switch reboot -------------------------------------------------------- When an exclusive LAG is set up that spans multiple hardware switches and one of those switches is rebooted, only partial connectivity is restored when the hardware switch comes back online. Some guests are no longer able to receive traffic. ABENDHTT001 HCPIVC+16E8 with 16 members in an IVL domain -------------------------------------------------------- With 16 members in an IVL domain, it is possible to encounter an HTT001 abend. PEVM66907 HCP3034E when a user couples two NICs to the same VSWITCH ----------------------------------------------------------- VM66907 addressed a problem where a user being relocated may encounter an error because the virtual port its NIC was connected to was already in use on the target system. With this fix applied, any user attempting to couple two NICs to the same VSWITCH will now receive an HCP3034E message and only one NIC will be able to be coupled.
Problem conclusion
As noted in details below, Firmware D61C Bundle 20 is required. OSH SET VSWITCH SWITCHOVER loses connectivity when there are 2 backup RDEVs -------------------------------------------------------------- In this scenario, the wrong control block was being stored into our routing entry so traffic was being routed to the wrong device. Code has been updated to select the appropriate control block for the routing table after the SWITCHOVER completes. The EQID of an EQDIO device is reset after a config off/on ---------------------------------------------------------- During config off processing, the deletion of the VDEV block associated with the device hung. This led to a new RDEV block being created when the device was configured back online. The new RDEV block did not have the EQID associated with it. Code has been changed to properly delete the VDEV block on config off such that the original RDEV (and EQID) are reused when the device is configured back online. VSWITCH error recovery message indicates a "persistent error condition" which results in a recovery loop ------------------------------------------------------------ Code has been changed to skip enabling the recovery timer for devices thathave encountered a persistent error condition. Additional monitor counters are needed for QDIO/EQDIO ----------------------------------------------------- A new monitor record (MRIODQEQ - D6 R55) has been defined to collect EQDIO queue based data. The user based counters already in MRUSEACT are also appropriately populated with this fix. z/OS guest receives error code 03 when deactivating EQDIO virtual NICs --------------------------------------------------------- The error code 03 was indicating that EQDIO simulation was processing an unexpected adapter command. This occurred because the code for cleaning up mulitcast addresses associated with the virtual NIC was assuming it was operating in layer 3 mode. Code has been updated to validate the transport mode the virtual adapter is operating in when cleaning up multicast addresses, and respond appropriately. Eliminate unnecessary EQDIO instructions to improve efficiency -------------------------------------------------------------- The manner in which z/VM tracks queue indicies for EQDIO adapters has been changed to eliminate the vast majority of the queries that are issued to the adapter for ensuring indicies stay in sync. This greatly improves the efficiency with which the EQDIO support operates. Unexpected ISOLATE message when a switch port is enabled for LAG ---------------------------------------------------------------- Code has been updated to not send an ISOLATE command to the EQDIO adapter when neither ISOLATE nor VEPA is enabled. LAG EQDIO VSWITCH does not attempt to initialize other devices if first device is disabled -------------------------------------------------------------- EQDIO initialzation logic has been updated to react appropriately when it encounters a device offline. Port group initialization will no longer halt when the first device is offline. EQDIO VSWITCH loses connectivity for some guests after a hardware switch reboot -------------------------------------------------------- This problem is addressed by a mixture of firmware and z/VM updates. For z/VM, initialization of link aggregation groups is now done in multiple steps. This is because gratuitious ARP packets that are used to announce MAC address changes when takeover events occur may be lost if they are sent before a link is fully LACP enabled. z/VM will now initially enable the EQDIO data plane for a LAG port just enough to flow LACP PDUs (but not guest data). Once the port becomes LACP enabled, the data plane will then be enabled for guest data as well and initialization will complete with full connectivity. Firmware D61C Bundle 20 is required. ABENDHTT001 HCPIVC+16E8 with 16 members in an IVL domain -------------------------------------------------------- This abend occurs when the IVL control block is allocated near the end of a 4K page. When sending a broadcast packet, the control loop stepping through the IVL domain was using an improper index which was causing it to address memory outside of the current page. Code has been updated to fix the indexing when stepping through the IVL members. PEVM66907 HCP3034E when a user couples two NICs to the same VSWITCH ----------------------------------------------------------- Code has been updated to fix an error with VM66907 that was improperly discerning the difference between a transient port number and a reserved port number. The following publication is updated as part of this APAR: z/VM Performance: MRIODQEQ is added to the list of monitor records D6 R55 EQDIO Queue-based counters
Temporary fix
Comments
APAR Information
APAR number
VM66920
Reported component name
VM CP CP
Reported component ID
568411202
Reported release
740
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2026-02-13
Closed date
2026-02-24
Last modified date
2026-03-24
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UM90590
Modules/Macros
CPLOAD HCPCPE HCPDTS HCPEQL HCPEQS HCPIOT HCPIPN HCPIQC HCPIQG HCPIVC HCPIVL HCPLLT HCPMDLAT HCPMES HCPMESB HCPMNO HCPMONEQ HCPMXD HCPMXD$ HCPNDF HCPNICBK HCPNIDBK HCPNVM HCPPRV HCPQDIO HCPRP HCPSWA HCPSWB HCPSWU HCPVLC HCPVLE HCPVLG HCPVLI HCPVLM HCPVQE HCPVQF HCPVQG HCPVQH HCPVQS MRIODQEQ MRUSEACT 7VMCPR40
| SC24630174 |
Fix information
Fixed component name
VM CP CP
Fixed component ID
568411202
Applicable component levels
R740 PSY UM90590
UP26/02/26 P 7404
Fix is available
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Document Information
Modified date:
24 March 2026