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Undetected data corruption on VSX load operations on CI memory

Flashes (Alerts)


Abstract

IBM internal testing has revealed a scenario that results in undetected data corruption during Vector Scalar Extension (VSX) load operations on Cache Inhibited (CI) memory under the following circumstances:
• IBM® POWER9™ systems with processors of level DD2.1, or lower.
• The OS-level buffer is not explicitly 16 byte aligned.
This issue is not reported in the field.

Content

Linux Releases Affected
This issue is known to impact the following Linux releases:
•    Red Hat® Enterprise Linux® 8.2
•    Red Hat Enterprise Linux 8.3
•    Ubuntu 20.04
•    Ubuntu 20.10
IBM Systems Affected
  • IBM Power System AC922 (models: 8335-GTC, 8335-GTW, and 8335-GTG)
  • IBM Power System LC922 (models: 5104-22C and 9006-22C)
Description
This issue is observed because of changes to build parameters in Red Hat Enterprise Linux (RHEL) RHEL 8.2, or later and Ubuntu Ubuntu 20.04, or later which uncovered the missing explicit 16 byte alignment.
Note: Changelog that is similar to the following message is displayed in the security advisory if the fix for the issue is available: Fix undetected data corruption with P9N DD2.1 VSX CI load emulation.
Fix Outlook
Fix for this issue is available for the following RHEL releases. The fix will be propagated to subsequent releases. Previous versions of RHEL are not known to exhibit this issue.
•    Red Hat Enterprise Linux 8.2 (https://access.redhat.com/errata/RHSA-2020:5418, kernel-4.18.0-193.37.1.el8_2)
•    Red Hat Enterprise Linux 8.3 (https://access.redhat.com/errata/RHSA-2020:5473, kernel-4.18.0-240.8.1.el8_3)
 
Fix for this issue is available for the following Ubuntu releases. The fix will be propagated to subsequent releases. Previous versions of Ubuntu are not known to exhibit this issue.
•    Ubuntu 20.04 (linux - 5.4.0-56.62)
•    Ubuntu 20.10 (linux - 5.8.0-31.33)

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Document Information

Modified date:
22 February 2021

UID

ibm16414615

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