一、模仿一个x86平台虚机
cpu虚拟化原理来源于Linux虚拟化KVM-Qemu分析(四)之CPU虚拟化(2)
笔者就实现了下相关操作。看汇编是在x86平台下操作的,其中两个文件分别是
1.tiny_kernel.S
start:
/* Hello */
mov $0x48, %al
outb %al, $0xf1
mov $0x65, %al
outb %al, $0xf1
mov $0x6c, %al
outb %al, $0xf1
mov $0x6c, %al
outb %al, $0xf1
mov $0x6f, %al
outb %al, $0xf1
mov $0x2c, %al
outb %al, $0xf1
/* world */
mov $0x77, %al
outb %al, $0xf1
mov $0x6f, %al
outb %al, $0xf1
mov $0x72, %al
outb %al, $0xf1
mov $0x6c, %al
outb %al, $0xf1
mov $0x64, %al
outb %al, $0xf1
mov $0x0a, %al
outb %al, $0xf1
hlt
2.tiny_qemu.c (这个用例程序写得很经典)
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <assert.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/kvm.h>
#include <sys/mman.h>
#define KVM_DEV "/dev/kvm"
#define TINY_KERNEL_FILE "./tiny_kernel.bin"
#define PAGE_SIZE 0x1000
int main(void)
{
int kvm_fd;
int vm_fd;
int vcpu_fd;
int tiny_kernel_fd;
int ret;
int mmap_size;
struct kvm_sregs sregs;
struct kvm_regs regs;
struct kvm_userspace_memory_region mem;
struct kvm_run *kvm_run;
void *userspace_addr;
/* open kvm device */
kvm_fd = open(KVM_DEV, O_RDWR);
assert(kvm_fd > 0);
/* create VM */
vm_fd = ioctl(kvm_fd, KVM_CREATE_VM, 0);
assert(vm_fd >= 0);
/* create VCPU */
vcpu_fd = ioctl(vm_fd, KVM_CREATE_VCPU, 0);
assert(vcpu_fd >= 0);
/* open tiny_kernel binary file */
tiny_kernel_fd = open(TINY_KERNEL_FILE, O_RDONLY);
assert(tiny_kernel_fd > 0);
/* map 4K into memory */
userspace_addr = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);
assert(userspace_addr > 0);
/* read tiny_kernel binary into the memory */
ret = read(tiny_kernel_fd, userspace_addr, PAGE_SIZE);
assert(ret >= 0);
/* set user memory region */
mem.slot = 0;
mem.flags = 0;
mem.guest_phys_addr = 0;
mem.memory_size = PAGE_SIZE;
mem.userspace_addr = (unsigned long)userspace_addr;
ret = ioctl(vm_fd, KVM_SET_USER_MEMORY_REGION, &mem);
assert(ret >= 0);
/* get kvm_run */
mmap_size = ioctl(kvm_fd, KVM_GET_VCPU_MMAP_SIZE, NULL);
assert(mmap_size >= 0);
kvm_run = (struct kvm_run *)mmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED, vcpu_fd, 0);
assert(kvm_run >= 0);
/* set cpu registers */
ret = ioctl(vcpu_fd, KVM_GET_SREGS, &sregs);
assert(ret >= 0);
sregs.cs.base = 0;
sregs.cs.selector = 0;
ret = ioctl(vcpu_fd, KVM_SET_SREGS, &sregs);
memset(®s, 0, sizeof(struct kvm_regs));
regs.rip = 0;
ret = ioctl(vcpu_fd, KVM_SET_REGS, ®s);
assert(ret >= 0);
/* vcpu run */
while (1) {
ret = ioctl(vcpu_fd, KVM_RUN, NULL);
assert(ret >= 0);
switch(kvm_run->exit_reason) {
case KVM_EXIT_HLT:
printf("----KVM EXIT HLT----\n");
close(kvm_fd);
close(tiny_kernel_fd);
return 0;
case KVM_EXIT_IO:
putchar(*(((char *)kvm_run) + kvm_run->io.data_offset));
break;
default:
printf("Unknow exit reason: %d\n", kvm_run->exit_reason);
break;
}
}
return 0;
}
程序原理很简单,就是模仿kvm-qemu那一套。
二、模仿一个arm平台虚机
本次虚拟机操作来源于https://www.cnblogs.com/pengdonglin137/p/14083316.html
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