# 安装依赖和前提条件

本页说明安装虚拟机模块的依赖和前提条件。

!!! info

    下述命令或脚本内出现的 __virtnest__ 字样是全局管理模块的内部开发代号。

## 前提条件

### 操作系统内核版本需要在 4.11 以上

目标集群所有节点的操作系统内核版本需要大于 4.11（详见 [kubevirt issue](https://github.com/kubevirt/kubevirt/issues/11886)）。
运行以下命令查看内核版本：

```bash
uname -a
```

示例输出：

```output
Linux master 6.5.3-1.el7.elrepo.x86_64 #1 SMP PREEMPT_DYNAMIC Wed Sep 13 11:46:28 EDT 2023 x86_64 x86_64 x86_64 GNU/Linux
```

### CPU 需支持 x86-64-v2 及以上的指令集

使用以下脚本检查当前节点的 CPU 是否支持：

!!! note  

    若出现与输出信息无关的报错（如下所示），可无需关注，不影响最终结果。

    ```bash title="示例"
    $ sh detect-cpu.sh
    detect-cpu.sh: line 3: fpu: command not found
    ```   

```sh
cat <<EOF > detect-cpu.sh
#!/bin/sh -eu

flags=$(cat /proc/cpuinfo | grep flags | head -n 1 | cut -d: -f2)

supports_v2='awk "/cx16/&&/lahf/&&/popcnt/&&/sse4_1/&&/sse4_2/&&/ssse3/ {found=1} END {exit !found}"'
supports_v3='awk "/avx/&&/avx2/&&/bmi1/&&/bmi2/&&/f16c/&&/fma/&&/abm/&&/movbe/&&/xsave/ {found=1} END {exit !found}"'
supports_v4='awk "/avx512f/&&/avx512bw/&&/avx512cd/&&/avx512dq/&&/avx512vl/ {found=1} END {exit !found}"'

echo "$flags" | eval $supports_v2 || exit 2 && echo "CPU supports x86-64-v2"
echo "$flags" | eval $supports_v3 || exit 3 && echo "CPU supports x86-64-v3"
echo "$flags" | eval $supports_v4 || exit 4 && echo "CPU supports x86-64-v4"
EOF
chmod +x detect-cpu.sh
sh detect-cpu.sh
```

### 所有节点必须启用硬件虚拟化（嵌套虚拟化）

* 运行以下命令检查：

    ```sh
    virt-host-validate qemu
    ```
    
    ```sh
    # 成功的情况
    QEMU: Checking for hardware virtualization                                 : PASS
    QEMU: Checking if device /dev/kvm exists                                   : PASS
    QEMU: Checking if device /dev/kvm is accessible                            : PASS
    QEMU: Checking if device /dev/vhost-net exists                             : PASS
    QEMU: Checking if device /dev/net/tun exists                               : PASS
    QEMU: Checking for cgroup 'cpu' controller support                         : PASS
    QEMU: Checking for cgroup 'cpuacct' controller support                     : PASS
    QEMU: Checking for cgroup 'cpuset' controller support                      : PASS
    QEMU: Checking for cgroup 'memory' controller support                      : PASS
    QEMU: Checking for cgroup 'devices' controller support                     : PASS
    QEMU: Checking for cgroup 'blkio' controller support                       : PASS
    QEMU: Checking for device assignment IOMMU support                         : PASS
    QEMU: Checking if IOMMU is enabled by kernel                               : PASS
    QEMU: Checking for secure guest support                                    : WARN (Unknown if this platform has Secure Guest support)
        
    # 失败的情况
    QEMU: Checking for hardware virtualization                                 : FAIL (Only emulated CPUs are available, performance will be significantly limited)
    QEMU: Checking if device /dev/vhost-net exists                             : PASS
    QEMU: Checking if device /dev/net/tun exists                               : PASS
    QEMU: Checking for cgroup 'memory' controller support                      : PASS
    QEMU: Checking for cgroup 'memory' controller mount-point                  : PASS
    QEMU: Checking for cgroup 'cpu' controller support                         : PASS
    QEMU: Checking for cgroup 'cpu' controller mount-point                     : PASS
    QEMU: Checking for cgroup 'cpuacct' controller support                     : PASS
    QEMU: Checking for cgroup 'cpuacct' controller mount-point                 : PASS
    QEMU: Checking for cgroup 'cpuset' controller support                      : PASS
    QEMU: Checking for cgroup 'cpuset' controller mount-point                  : PASS
    QEMU: Checking for cgroup 'devices' controller support                     : PASS
    QEMU: Checking for cgroup 'devices' controller mount-point                 : PASS
    QEMU: Checking for cgroup 'blkio' controller support                       : PASS
    QEMU: Checking for cgroup 'blkio' controller mount-point                   : PASS
    WARN (Unknown if this platform has IOMMU support)
    ```

* 安装 virt-host-validate：

    === "在 CentOS 上安装"
    
        ```bash
        yum install -y qemu-kvm libvirt virt-install bridge-utils
        ```
    
    === "在 Ubuntu 上安装"
    
        ```bash
        apt install qemu-kvm libvirt-daemon-system libvirt-clients bridge-utils
        ```
    
* 硬件虚拟化启用方法：

    不同平台启用硬件虚拟化的方法也不一样，以 vsphere 为例，
    方法请参照 [vmware 官网文档](https://docs.vmware.com/en/VMware-vSphere/7.0/com.vmware.vsphere.vm_admin.doc/GUID-2A98801C-68E8-47AF-99ED-00C63E4857F6.html)。

### 如果使用 Docker Engine 作为容器运行时

如果集群使用 Docker Engine 作为容器运行时，则 Docker Engine 版本需要大于 20.10.10
 
### 建议开启 IOMMU

为了后续功能做准备，建议开启 IOMMU。