KSM is an out-of-tree x86_64 VT-x hypervisor. The developer Ahmed Samy announced of the project, "KSM's purpose is not to run other kernels, but more of researching (or whatsoever) the running kernel, some ideas would be sandboxing, debugging perhaps."
This "fast and simple" hypervisor also supports Windows while macOS support is also planned. The GitHub project site goes on to describe it, "KSM's purpose is not to run other Operating Systems, instead, KSM can be used as an extra layer of protection to the existing running OS. This type of virtualization is usually seen in Anti-viruses, or sandboxers or even Viruses. KSM also supports nesting, that means it can emulate other hardware-assisted virtualization tools (VT-x) such as KVM or itself." Learn more on the project's site.