Performance impact observed after Red Hat Enterprise Linux upgrade due to Retbleed CVE vulnerability mitigations

Issue

• Upgrading from a RHEL kernel without Retbleed (CVE-2022-29900 / CVE-2022-23816, CVE-2022-29901, CVE-2022-23825) vulnerability mitigations to a kernel that does support Retbleed mitigations may result in a performance impact. Observed primarily on the Intel Skylake family of Processors.
• This can happen when upgrading from older RHEL 7.x, 8.x, or 9.0 kernels without Retbleed vulnerability mitigations to a newer RHEL kernel with Retbleed vulnerability mitigations.
• Common examples also include updating OpenShift Container Platform (OCP) version 4.10 to 4.11 or 4.10 to 4.12.
• How much of a performance impact do I get from the Retbleed mitigation?