QEMU Source Code Study - KVM_RUN

QEMU Part

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Like KVM_VCPU_CREATE(), kvm_cpu_exec() is also called by function "qemu_kvm_cpu_thread_fn(...)". For the execution process of qemu_kvm_cpu_thread_fn(...), please check the KVM_VCPU_CREATE() post.

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kvm_vcpu_exec()

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kvm_arch_pre_run(cpu, run)

struct kvm_run

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KVM Part

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kvm_vcpu_ioctl(...)

kvm_arch_vcpu_ioctl(filp, ioctl, arg)

vcpu_enter_guest(kvm_vcpu *vcpu)

vmx_vcpu_run( kvm_vcpu *vcpu)

vmx_handle_exit()

static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu)

QEMU Source Code Study (3) - KVM_CREATE_VCPU

x86_cpu_register_types() ----> type_register_static(&x86_cpu_type_info) ----> TypeInfo x86_cpu_type_info.class_init = x86_cpu_common_class_init ----> x86_cpu_common_class_init(ObjectClass *oc, void *data) ----> dc->realize = x86_cpu_realizefn ----> x86_cpu_realizefn(DeviceState *dev, Error **error) ----> qemu_init_vcpu(cpu) ----> qemu_kvm_start_vcpu(cpu) ----> qemu_thread_create(cpu->thread, qemu_kvm_cpu_thread_fn, cpu) ----> nqemu_kvm_cpu_thread_fn(arg) ----> kvm_cpu_exec(cpu) ----> kvm_vcpu_ioctl(cpu, KVM_RUN, 0);


How to execute these object?

QEMU Part

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kvm_init_vcpu(...)

KVM Part

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kvm_vm_ioctl()

kvm_vm_ioctl_create_vcpu(kvm, id)

kvm_x86_ops

vmx_create_vcpu

QEMU Source Code Study (2) - KVM_init

At first, main() in vl.c will call configure_accelerator()

QEMU Part

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configure_accelerator()

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accel_list[]

kvm_init()

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KVMState

kvm_ioctl(KVMState *s, int type, ...)

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KVM Part

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Register ioctl handler

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vmx_init() -> kvm_init(...) -> misc_register(kvm_dev) -> kvm.&kvm_chardev_ops

kvm_dev

kvm_chardev_ops

KVM API

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The "/dev/kvm" ioctl handler is as follows:

KVM_GET_API_VERSION

This API just return the API version of KVM. The handler just return he version of KVM. This parameter is defined in ./include/uapi/linux/kvm.h

KVM_CREATE_VM

This API is used by QEMU to ask KVM create VM. "KVM_CREATE_VM" definition is the same as KVM_GET_API_VERSION.

Binary Tree

Data Structure

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Binary Tree Construction

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• Recursive
• Iterative

Pre-Order

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• Recursive
• Iterative

In-Order

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• Recursive
• Iterative

Post-Order

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• Recursive
• Iterative

Maximum Depth of Binary Tree

Question

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Given a binary tree, find its maximum depth.
The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

Solution

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Use recursive method to solve this problem. Retrieve the left part of binary tree and then the right part of binary tree.

• If the node is empty then return 0
• If the node is not empty then retrieve left part then retrieve right part. The return value will be (the max path length between left and right) + 1.

Code

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SeaBIOS - Interface_init

SeaBIOS - Source Code Study (2)

QEMU_PREINIT(void)

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• qemu_detect(void)

dopost()

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In this function, besides the qemu_preinit(). It will be responsible to allocate memory, init serial port, make BIOS writable, and start the main function in qemu: maininit()

maininit(): most important entrypoint for SeaBIOS

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