Disclosed back in August was the Inception vulnerability affecting all Zen processors. It took until today though for the mainline Linux kernel to mitigate Hygon processors for this vulnerability for those Zen 1 CPUs formed from the AMD-Chinese joint venture.

With the Hygon processors being based on Zen 1, it was assumed Hygon was affected too by this CPU security vulnerability from August. But due to only a few days ago was the patch sent out for mitigating the Speculative Return Stack Overflow (SRSO / Inception) on these processors. Mitigating is just a one-liner that requires just adding "SRSO" to the 0x18 Hygon family for then following the mitigated kernel path written by AMD engineers, so it's a bit surprising it took so long to act.