kernel debug between two qemu/kvm machines

I’m debugging windows 7 system inside kvm.
I use windbg and virtual serial ,but it’s too slow .
Is there any other way faster than virtual serial debug ?

Not with Win7. KDNET should be much faster but requires Windows 8 or later on the target machine.

Thanks Scott.
I am debugging qxl display driver (xddm model).
So I need a win7 target.