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

Michal Prívozník mprivozn at redhat.com
Fri May 14 13:15:45 UTC 2021


On 5/14/21 8:33 AM, Liang Chaojun wrote:
> 
> 
> Thanks,I have tried qemu monitor as below. I used chardev_add to add a chardev and used device_add it to running vm. But i often hit a issue and cause the vm crash. qemu-system-x86_64: ../hw/virtio/vhost.c:1566: vhost_dev_get_config: Assertion `hdev->vhost_ops' failed.
> 
> virsh qemu-monitor-command spdk1 --hmp --cmd "chardev-add socket,id=spdk_vhost_blk0,path=/var/tmp/vhost.0,reconnect=1"  virsh qemu-monitor-command spdk1 --hmp --cmd "device_add vhost-user-blk-pci,chardev=spdk_vhost_blk0,num-queues=4"

Smells like problem described here:

https://gitlab.com/qemu-project/qemu/-/commit/bc79c87bcde6587a37347f81332fbb0cd6b14b85

But that's pretty fresh commit (part of qemu 6.0.0 release). And also
the commit it references is not that old (qemu 5.1.0 release). What
version of qemu are you running?

Michal




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