All About Computer Science

First, in Qemu, QEMU Process order "kvm-vcpu" to run like this

first,  x86_cpu_realizefn calls qemu_init_vcpu , in qemu/target-i386/cpu.c

2) qemu_init_vcpu calls qemu_kvm_start_vcpu , in cpus.c

3) qemu_kvm_start_vpuc calls qemu_kvm_cpu_thread_fn through creating thread, in cpus.c

4) qemu_kvm_cpu_thread_fn calls kvm_init_vcpu to initialize kvm_vcpu and then calls kvm_cpu_exec, in cpus.c

5) kvm_cpu_exec calls kvm_vpuc_ioctl for running vcpu stored in kvm-vcpu file.

then, in linux kernel, KVM modules get an order to run "vcpu" through "kvm-vcpu" anonymous file. so, called

1) kvm_vcpu_ioctl through ioctl function for kvm-vcpu is file operation "kvm_vcpu_fops" , in /virt/kvm/kvm_main.c

2) kvm_vcpu_ioctl calls kvm_arch_vcpu_ioctl_run , in /virt/kvm/kvm_main.c

3) kvm_arch_vcpc_ioctl_run calls __vcpu_run , in /arch/x86/kvm/x86.c

4) __vcpu_run calls vcpu_enter_guest , in /arch/x86/kvm/x86.c ( and while loop calls vcpu_enter_guest until return value is equal or more than zero)

5) vcpu_enter_guest calls x86 operations for VM already initialized when launching kvm modules, and also calls kvm_guest_enter and  kvm_x86_ops->run , in /arch/x86/kvm/x86.c

at the last post of this section, i posted kvm has  two parts. i.e) kvm kernel and QEMU for guest, and also where to start analyzing kvm kernel as a kernel modules.

in this post, i'm just about to analyze kvm_init.

kvm_init is doing as following functions.

1. kvm_arch_init: initialize architecture oriented operation

2. kvm_irqfd_init: initialize interrupt, but but nothing to do with this. i have no idea why doing nothing.

3. zalloc_cpumask_var: cpu mask variable initialization.

4. kvm_arch_hardware_setup: architecture oriented hardware setup. in case of x86, it will call "kvm_x86_ops->hardware_setup()" function in x86.c,  already initialized in kvm_init, kvm_arch_init(opaque), hardware_setup was set up in svm.c or vmx.c

5. kmem_cache_create: creating kernel cache for kvm vcpu

you can see hole init_kvm functions on mygithub