How to hot plugin a new vhost-user-blk-pci device to running VM?

[Liang Chaojun]

Hi Guy,

Does  anyone clear how to hot plugin a new vhost-user-blk-pci device to a running VM?

Before staring vm , I pass the disk through QEMU command line  like below.

<qemu:commandline>
 <qemu:arg value='-object'/>
 <qemu:arg value='memory-backend-file,id=mem0,size=4G,mem-path=/dev/hugepages,share=on'/>
 <qemu:arg value='-numa'/>
 <qemu:arg value='node,memdev=mem0'/>
 <qemu:arg value='-chardev'/>
 <qemu:arg value='socket,id=spdk_vhost_blk721ea46a-b306-11eb-a280-525400a98761,path=/var/tmp/vhost.721ea46a-b306-11eb-a280-525400a98761,reconnect=1'/>
 <qemu:arg value='-device'/>
 <qemu:arg value='vhost-user-blk-pci,chardev=spdk_vhost_blk721ea46a-b306-11eb-a280-525400a98761,bootindex=1,num-queues=4'/>
 <qemu:arg value='-chardev'/>
 <qemu:arg value='socket,id=spdk_vhost_blk2f699c58-d222-4629-9fdc-400c3aadc55e,path=/var/tmp/vhost.2f699c58-d222-4629-9fdc-400c3aadc55e,reconnect=1'/>
 <qemu:arg value='-device'/>
 <qemu:arg value='vhost-user-blk-pci,chardev=spdk_vhost_blk2f699c58-d222-4629-9fdc-400c3aadc55e,num-queues=4'/>
</qemu:commandline>

But I don’t know how to live add a vhost-user-blk-pci device on running VM even with calling attachDevice API now.

OS: redhat 7.4 Libvirt version: 3.4

Your help will be appreciated.


Thanks!