This was merged.
How about Speculative Return Stack Overflow (SRSO) β The Linux Kernel documentation?
Quote https://www.kernel.org/doc/Documentation/admin-guide/kernel-parameters.txt
spec_rstack_overflow=
[X86] Control RAS overflow mitigation on AMD Zen CPUs
off - Disable mitigation
microcode - Enable microcode mitigation only
safe-ret - Enable sw-only safe RET mitigation (default)
ibpb - Enable mitigation by issuing IBPB on
kernel entry
ibpb-vmexit - Issue IBPB only on VMEXIT
(cloud-specific mitigation)
See also:
cat /sys/devices/system/cpu/vulnerabilities/spec_rstack_overflow