  We study a particular exact solution for rotating spacetimes in
four-dimensional Horava gravity, which has been proposed as a renormalizable
gravity model without the ghost problem. We show that the massless Kerr
spacetime or the massless Kerr-(A)dS spacetime in Einstein gravity is an exact
solution in four-dimensional Horava for an arbitrary IR Lorentz-violation
parameter lambda, but with an appropriate cosmological constant. In particular,
for the massless topological Kerr-AdS black hole solution with the hyperbolic
horizon topology or the massless Kerr-dS cosmological solution with the
spherical horizon topology, there exist the ergosphere and the non-vanishing
Hawking temperature, which imply the existence of negative mass black holes as
well as positive mass spacetimes, by losing its mass from the massless ones via
the Hawking radiation or Penrose process in the ergosphere.
