Bug 1897710

Summary: live attach of virtiofs file device fails
Product: Red Hat Enterprise Linux 8 Reporter: Tom Barron <tbarron>
Component: qemu-kvmAssignee: Virtualization Maintenance <virt-maint>
qemu-kvm sub component: virtio-fs QA Contact: menli <menli>
Status: CLOSED INSUFFICIENT_DATA Docs Contact:
Severity: unspecified    
Priority: unspecified CC: drjones, gouthamr, jinzhao, jtomko, virt-maint
Version: ---   
Target Milestone: rc   
Target Release: 8.0   
Hardware: Unspecified   
OS: Unspecified   
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Clone Of: Environment:
Last Closed: 2020-11-17 21:34:45 UTC Type: Bug
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On:    
Bug Blocks: 1887471, 1897708    

Description Tom Barron 2020-11-13 20:44:17 UTC 
Description of problem:

  # virsh attach-device --live <domain> filesystem.xml

yields:

  error: Failed to attach device from filesystem.xml
  error: Operation not supported: live attach of device 'filesystem' is not supported

whereas:

  # virsh attach-device --persistent <domain> filesystem.xml

works and with subsequent 'virsh start' of the domain and an accompanying virtiofsd process sharing between host and guest works fine.

Version-Release number of selected component (if applicable):

[test@osp-storage-04 ~]$ virsh --version
6.0.0


How reproducible:

100%

Steps to Reproduce:
1.  Define a domain with shared memory backing and numa topology as at https://libvirt.org/kbase/virtiofs.html
2.  virsh start the guest VM
3.  attempt 'virsh attach-device --live <domain> filesystem.xml' with appropriate XML device configuration as described at the just-mentioned Kbase.

Actual results:

Error message as reported.

Expected results:  Successful hot-plug attach of the virtiofs files sytem to the running guest.

Would expect corresponding 'virsh detatch-device --live ...' commands to work as well.

Additional info:

We need this to work for OpenStack Nova to support virtiofs devices.

It could be that all the work for this fix is in libvirt and will be done in BZ1897708.  I will make that BZ depend on this one in case there is also work needed in qemu-kvm to enable hotplug support.
Comment 1 Ademar Reis 2020-11-17 21:34:45 UTC 
Let's start with the libvirt BZ you've already opened, then the team will identify if any and which work is needed in QEMU.

*** This bug has been marked as a duplicate of bug 1897708 ***