Why RISC-V doesn't (yet) support KVM

As far as userspace is concerned, the API is only based on ratified specifications. The details of the hypervisor spec is completely hidden within Linux code. At the same time, until KVM is merged into upstream Linux the whole stack (QEMU, kvmtool) has to be developed in a fork, and new kernel features are harder to review. All this is simply *not how Linux is developed*.