wordpress横幅图像,seo关键词选取工具,网推app,商业网站制作价格qemu/kvm架构 cpu虚拟化的示例
Reference: kvmtest.c [LWN.net]
主要步骤#xff1a;
QEMU通过/dev/kvm设备文件发起KVM_CREATE_VM ioctl#xff0c;请求KVM创建一个虚拟机。KVM创建虚拟机相应的结构体#xff0c;并为QEMU返回一个虚拟机文件描述符QEMU通过虚拟机文件描述…qemu/kvm架构 cpu虚拟化的示例
Reference: kvmtest.c [LWN.net]
主要步骤
QEMU通过/dev/kvm设备文件发起KVM_CREATE_VM ioctl请求KVM创建一个虚拟机。KVM创建虚拟机相应的结构体并为QEMU返回一个虚拟机文件描述符QEMU通过虚拟机文件描述符发起KVM_CREATE_VCPU ioctl请求KVM创建一个vCPU。KVM创建vCPU相应的结构体并初始化返回一个vCPU文件描述符。QEMU通过vCPU文件描述符发起KVM_RUN ioctlvCPU线程执行VMLAUNCH指令进入非根模式执行虚拟机代码直至发生VM-Exit。KVM根据VM-Exit的原因进行相应处理如果与IO有关则需要进一步返回到QEMU中进行处理。
运行结果 代码实现
/* Sample code for /dev/kvm API */#include err.h
#include fcntl.h
#include linux/kvm.h
#include stdint.h
#include stdio.h
#include stdlib.h
#include string.h
#include sys/ioctl.h
#include sys/mman.h
#include sys/stat.h
#include sys/types.hint main(void)
{int kvm, vmfd, vcpufd, ret;const uint8_t code[] {/* 写入指定端口 0x3f8输出 Hello */0xba, 0xf8, 0x03, /* mov $0x3f8, %dx */0x00, 0xd8, /* add %bl, %al */0x04, 0, /* add $0, %al */0xee, /* out %al, (%dx) */0xb0, \n, /* mov $\n, %al */0xee, /* out %al, (%dx) */0xb0, H, /* mov $H, %al */0xee, /* out %al, (%dx) */0xb0, e, /* mov $e, %al */0xee, /* out %al, (%dx) */0xb0, l, /* mov $l, %al */0xee, /* out %al, (%dx) */0xb0, l, /* mov $l, %al */0xee, /* out %al, (%dx) */0xb0, o, /* mov $o, %al */0xee, /* out %al, (%dx) */0xb0, \n, /* mov $\n, %al */0xee, /* out %al, (%dx) */0xf4, /* hlt */};uint8_t *mem;struct kvm_sregs sregs;size_t mmap_size;struct kvm_run *run;// ** step 1. 打开 KVM 模块设备文件kvm open(/dev/kvm, O_RDWR | O_CLOEXEC);if (kvm -1)err(1, /dev/kvm);// 获取 KVM API 版本/* Make sure we have the stable version of the API */ret ioctl(kvm, KVM_GET_API_VERSION, NULL);if (ret -1)err(1, KVM_GET_API_VERSION);if (ret ! 12)errx(1, KVM_GET_API_VERSION %d, expected 12, ret);// ** step 2. KVM_CREATE_VM 创建虚拟机获得虚拟机文件描述符vmfd ioctl(kvm, KVM_CREATE_VM, (unsigned long)0);if (vmfd -1)err(1, KVM_CREATE_VM);// 分配 4KB 内存空间存放二进制代码// 这里的 0x1000(HVA)/* Allocate one aligned page of guest memory to hold the code. */mem mmap(NULL, 0x1000, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);if (!mem)err(1, allocating guest memory);// 将二进制代码复制至分配的内存页中memcpy(mem, code, sizeof(code));// KVM_SET_USER_MEMORY_REGION 将该内存页映射至虚拟机物理地址 0x1000(GPA) 处/* Map it to the second page frame (to avoid the real-mode IDT at 0). */struct kvm_userspace_memory_region region {.slot 0,.guest_phys_addr 0x1000,.memory_size 0x1000,.userspace_addr (uint64_t)mem,};ret ioctl(vmfd, KVM_SET_USER_MEMORY_REGION, region);if (ret -1)err(1, KVM_SET_USER_MEMORY_REGION);// ** step 3. KVM_CREATE_VCPU 创建 vCPU 获得 vCPU 文件描述符vcpufd ioctl(vmfd, KVM_CREATE_VCPU, (unsigned long)0);if (vcpufd -1)err(1, KVM_CREATE_VCPU);// ** step 4. 获取 QEMU/KVM 共享内存空间大小并映射 kvm_run 结构体/* Map the shared kvm_run structure and following data. */ret ioctl(kvm, KVM_GET_VCPU_MMAP_SIZE, NULL);if (ret -1)err(1, KVM_GET_VCPU_MMAP_SIZE);mmap_size ret;if (mmap_size sizeof(*run))errx(1, KVM_GET_VCPU_MMAP_SIZE unexpectedly small);// 使用 vCPU 文件描述符// 映射 kvm_run 结构体run mmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED, vcpufd, 0);if (!run)err(1, mmap vcpu);// ** step 5. 设置 CS 寄存器和 RIP 寄存器使得 vCPU 从 0x1000 处开始执行/* Initialize CS to point at 0, via a read-modify-write of sregs. */ret ioctl(vcpufd, KVM_GET_SREGS, sregs);if (ret -1)err(1, KVM_GET_SREGS);sregs.cs.base 0;sregs.cs.selector 0;ret ioctl(vcpufd, KVM_SET_SREGS, sregs);if (ret -1)err(1, KVM_SET_SREGS);/* Initialize registers: instruction pointer for our code, addends, and* initial flags required by x86 architecture. */struct kvm_regs regs {.rip 0x1000,.rax 2,.rbx 2,.rflags 0x2,};ret ioctl(vcpufd, KVM_SET_REGS, regs);if (ret -1)err(1, KVM_SET_REGS);/* Repeatedly run code and handle VM exits. */while (1) {// ** step 6. KVM_RUN 运行 vCPUret ioctl(vcpufd, KVM_RUN, NULL);if (ret -1)err(1, KVM_RUN);// ** step 7. 处理 VM-Exitswitch (run-exit_reason) {case KVM_EXIT_HLT: // hlt 指令触发 VM-Exitputs(KVM_EXIT_HLT);return 0; // 退出程序case KVM_EXIT_IO: // 依次调用 out 指令向 0x3f8 端口写入字符时会触发 VM-Exit使得程序返回到用户态处理// 输出写入 0x3f8 端口的字符if (run-io.direction KVM_EXIT_IO_OUT run-io.size 1 run-io.port 0x3f8 run-io.count 1)// 调用 putchar 函数输出字符putchar(*(((char *)run) run-io.data_offset));elseerrx(1, unhandled KVM_EXIT_IO);break;case KVM_EXIT_FAIL_ENTRY:errx(1, KVM_EXIT_FAIL_ENTRY: hardware_entry_failure_reason 0x%llx,(unsigned long long)run-fail_entry.hardware_entry_failure_reason);case KVM_EXIT_INTERNAL_ERROR:errx(1, KVM_EXIT_INTERNAL_ERROR: suberror 0x%x, run-internal.suberror);default:errx(1, exit_reason 0x%x, run-exit_reason);}}
}KVM API
/usr/include/linux/kvm.h
ioctlKVM APIDescriptionExample ioctls for /dev/kvm fds KVM_GET_API_VERSION 获取 KVM API 版本 kvm open(/dev/kvm, O_RDWR | O_CLOEXEC) ret ioctl(kvm, KVM_GET_API_VERSION, NULL) KVM_CREATE_VM 创建虚拟机获得虚拟机文件描述符 vmfd ioctl(kvm, KVM_CREATE_VM, 0) ioctls for VM fds KVM_SET_USER_MEMORY_REGION 将内存页映射至虚拟机物理地址处 ret ioctl(vmfd, KVM_SET_USER_MEMORY_REGION, region) KVM_CREATE_VCPU 创建 vCPU 获得 vCPU 文件描述符 vcpufd ioctl(vmfd, KVM_CREATE_VCPU, 0) KVM_GET_VCPU_MMAP_SIZE 获取 QEMU/KVM 共享内存空间大小 mmap_size ioctl(kvm, KVM_GET_VCPU_MMAP_SIZE, NULL); 使用 vCPU 文件描述符映射 kvm_run 结构体 run mmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED, vcpufd, 0) ioctls for vcpu fds KVM_GET_SREGS 获取 CS 寄存器和 RIP 寄存器 ret ioctl(vcpufd, KVM_GET_SREGS, sregs) KVM_SET_SREGS 设置 CS 寄存器和 RIP 寄存器 sregs.cs.base 0 sregs.cs.selector 0 ret ioctl(vcpufd, KVM_SET_SREGS, sregs) struct kvm_regs regs { .rip 0x1000, .rax 2, .rbx 2, .rflags 0x2, } ret ioctl(vcpufd, KVM_SET_REGS, regs) KVM_RUN 运行 vCPU ret ioctl(vcpufd, KVM_RUN, NULL)
