Through a labyrinthian sequence of includes, usage of virt_to_phys() is
dependent on the include of asm/io.h in asm/realmode.h via asm/acpi.h.
Explicitly include asm/io.h to break the dependency on realmode.h so
that a future patch can remove the realmode.h include from acpi.h
without breaking the build.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Link: https://lkml.kernel.org/r/20191126165417.22423-6-sean.j.christopherson@intel.comSigned-off-by: Ingo Molnar <mingo@kernel.org>