Linux kernel configuration option for disabling all specter/meltdown migration

I am compiling a kernel that is meant to be run in vm and only run
trusted softwares, so I'd like to turn off specter/meltdown migration
as they are of no use but only holds back the performance.

However, I didn't find any related option except for CONFIG_RETPOLINE.

If there isn't a kernel config in the mainline kernel, then is there
any patch that would allow me to disable them?

Thanks in advance.