I want to use the hypercall of kvm to communicate (just send strings, it is uni-directional) between the guest and vmm instead of creating a network channel between the guest os and host. I have only found the file arch/x86/include/asm/kvm_para.h in linux kernel? Is it similar to the system call of linux? How can I call these functions from the user level process running inside the guest os? Is there any manual or documents for this? Or can you give some examples of utilizing this mechanisms. Thanks