1. 问题描述及原因分析

在飞腾5000C的服务器环境下，通过virsh create cirros.xml命令启动虚拟机，报如下错误：

错误：从 cirros.xml 创建域失败
错误：internal error: qemu unexpectedly closed the monitor: 2024-01-25T02:23:36.085930Z qemu-kvm: kvm_init_vcpu: kvm_arch_init_vcpu failed (0): Invalid argument

cirros.xml文件内容如下：

<domain type='kvm' id='1'>
  <name>cirros</name>
  <memory unit='KiB'>4194304</memory>
  <currentMemory unit='KiB'>4194304</currentMemory>
  <vcpu placement='static'>2</vcpu>
  <resource>
    <partition>/machine</partition>
  </resource>
  <os>
    <type arch='aarch64' machine='virt-rhel8.4.0'>hvm</type>
  </os>
  <devices>
    <emulator>/usr/libexec/qemu-kvm</emulator>
    <disk type='file' device='cdrom'>
      <driver name='qemu'/>
      <target dev='sda' bus='scsi'/>
      <readonly/>
      <boot order='2'/>
      <alias name='scsi0-0-0-0'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/var/lib/libvirt/images/cirros-0.6.0-aarch64-disk.img' index='1'/>
      <backingStore/>
      <target dev='sdb' bus='scsi'/>
      <boot order='1'/>
      <alias name='scsi0-0-0-1'/>
      <address type='drive' controller='0' bus='0' target='0' unit='1'/>
    </disk>
  </devices>
</domain>

为了验证如上问题，我们直接通过qemu-kvm的命令

qemu-kvm --machine virt -cpu cortex-a57

发现也报

qemu-kvm: kvm_init_vcpu failed: Invalid argument

cortex-a57通过qemu-kvm --machine virt -cpu help查出来的，估计虽然在国产平台显示是支持该款CPU的，实际并不支持，不过如下CPU支持

qemu-kvm --machine virt -cpu Kunpeng-920

为了安全起见我们直接采用host模式

qemu-kvm --machine virt -cpu host

可以成功启动qemu模拟器，故我们改造xml文件，加入host模式，如下

  <cpu mode='host-passthrough' check='none'/>

通过virsh create cirros.xml可以成功启动虚拟机，判断为若不指定CPU MODE，会选择到libvirt默认指定的型号，国产平台不一定能支持，故出现kvm_init_vcpu failed: Invalid argument。

---

2. 解决方案：

在xml里明确指定cpu mode，国产平台一般采用host-passthrough模式更为稳妥，如下，比较完整的cirros.xml如下：

<domain type='kvm' id='1'>
  <name>cirros</name>
  <memory unit='KiB'>4194304</memory>
  <currentMemory unit='KiB'>4194304</currentMemory>
  <vcpu placement='static'>2</vcpu>
  <resource>
    <partition>/machine</partition>
  </resource>
  <os>
    <type arch='aarch64' machine='virt-rhel8.4.0'>hvm</type>
  </os>
  <features>
    <gic version='3'/>
  </features>
  <cpu mode='host-passthrough' check='none'/>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>destroy</on_crash>
  <devices>
    <emulator>/usr/libexec/qemu-kvm</emulator>
    <disk type='file' device='cdrom'>
      <driver name='qemu'/>
      <target dev='sda' bus='scsi'/>
      <readonly/>
      <boot order='2'/>
      <alias name='scsi0-0-0-0'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/var/lib/libvirt/images/cirros-0.6.0-aarch64-disk.img' index='1'/>
      <backingStore/>
      <target dev='sdb' bus='scsi'/>
      <boot order='1'/>
      <alias name='scsi0-0-0-1'/>
      <address type='drive' controller='0' bus='0' target='0' unit='1'/>
    </disk>
  </devices>
</domain>

3.参考文献

https://libvirt.org/drvqemu.html
https://blog.csdn.net/avatar_2009/article/details/107666014