On Thu, May 13, 2021 at 15:25:23 +0800, 梁朝军 wrote:
> 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.
You need to use the proper and supported way to use vhost-user-blk:
<disk type='vhostuser' device='disk'>
<driver name='qemu' type='raw'/>
<source type='unix' path='/tmp/vhost-blk.sock'>
<reconnect enabled='yes' timeout='10'/>
</source>
<target dev='vdf' bus='virtio'/>
</disk>
That works also with attachDevice.
> OS: redhat 7.4 Libvirt version: 3.4
This is obviously way too old for it. You'll need at least libvirt-7.1
for that.
