CVE-2022-27672

A flaw was found in HW. When SMT is enabled, certain AMD processors may speculatively execute instructions using a target from the sibling thread after an SMT mode switch, potentially resulting in information disclosure.

Mitigation

The current mitigations for spectre V4 (or spectre_v2) should mitigate this flaw, no additional steps will need to be taken.

In more details, according to the article
<https://kernel.org/doc/html//next/admin-guide/hw-vuln/cross-thread-rsb.html&gt;

Two mitigations are needed:

1. Stuff the RSB during context switch which is already being done in RHEL8/RHEL9 as long as the spectre_v2 mitigation is active.
2. For KVM, the mitigation for the KVM_CAP_X86_DISABLE_EXITS capability can be turned on using the boolean module parameter mitigate_smt_rsb, e.g. vm.mitigate_smt_rsb=1.

The command to check if mitigation is active:
cat /sys/devices/system/cpu/vulnerabilities/spectre_v2