Also you do not need to rebuild the kernel, there is a shorter list of
what needs to be rebuilt. The most overlooked one is to run (cd /usr/src; make
includes) so that the change of vmm.h gets installed into /usr/include, after
that you just need to rebuild vmm.ko, libvmmapi, and bhyve/bhyveload.
This work is still not merged to stable/11, iirc I ran into other intervening
commits that have blocked that merge.