Visible to Intel only — GUID: tnu1685986545782
Ixiasoft
Visible to Intel only — GUID: tnu1685986545782
Ixiasoft
3.5.5. 2675030: Multiple Events reported to Event queue for a single transaction
Description
To avoid a synchronization deadlock, when a synchronization occurs, invalidated translations in the TBU might discard their translation and fetch a translation again.
Affected versions treat translation faults as invalidated. As a result, a transaction that faults in the TCU reports an event, and returns a fault response to the TBU might have its fault response discarded by the TBU and a new translation fetched from the TCU.
This new translation request can:
- Fault in the same manner, causing a repeated event to be reported
- Fault in a different manner, causing two different events to be reported for the same transaction
- Succeed, causing an event to be recorded for a transaction that has translated successfully
It is possible, but unlikely, that this sequence can occur multiple times.
Conditions
The issue can occur when:
- The event queue is enabled
- A transaction encounters a fault during translation that results in an event being reported
- That transaction has an ordering requirement in the TBU to be issued behind, or responded after, a second transaction
- A synchronization request arrives at the TBU from the TCU
Impact
The software that reads the content of the event queue might encounter events that relate to a transaction for which it has already read an event from the queue. The result of this depends on the behavior of the software.
Workaround
No workaround is required
Category
Category C