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Bug 1368774

Summary:	libvirt changes the guest xml on target host even if migration failed
Product:	Red Hat Enterprise Linux 7	Reporter:	yafu <yafu>
Component:	libvirt	Assignee:	Jiri Denemark <jdenemar>
Status:	CLOSED ERRATA	QA Contact:	Virtualization Bugs <virt-bugs>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	7.3	CC:	aperotti, dyuan, fjin, mkolaja, mzhan, rbalakri, xuzhang, yanqzhan, zpeng
Target Milestone:	rc	Keywords:	Regression
Target Release:	---
Hardware:	x86_64
OS:	Linux
Whiteboard:
Fixed In Version:	libvirt-2.0.0-9.el7	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2016-11-03 18:53:47 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description yafu 2016-08-21 11:23:03 UTC

Description of problem:
libvirt changes the guest xml on target host even if migration failed

Version-Release number of selected component (if applicable):
libvirt-2.0.0-5.el7.x86_64
qemu-kvm-rhev-2.6.0-21.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
 
1.set this in source host qemu.conf and restart libvirtd service:

security_driver = "none"

2.set this in target host qemu.conf and restart libvirtd service:

security_driver = "selinux"

3.start a guest without seclabel in source, check the live xml of guest :
#virsh dumpxml rhel7.3
no seclabel

4. migrate to target with option(success):

# virsh migrate rhel7.3 --live qemu+ssh://yafu-test/system --dname rhel73-2 --verbose --p2p --tunnelled

5.try to migrate this guest back to source(fail and cause this issue):

# virsh migrate rhel73-2 --live qemu+ssh://test1/system --dname rhel7.3
error: unsupported configuration: Unable to find security driver for label selinux

6.then destroy target guest:

# virsh destroy rhel73-2
Domain rhel73-2 destroyed

7.start guest on source host again:
#virsh start rhel7.3
error: Failed to start domain rhel7.3
error: unsupported configuration: Unable to find security driver for model selinux

8.Check the xml of rhel7.3 on source host, seclabel was added:
#virsh dumpxml rhel7.3
...
<seclabel type='dynamic' model='selinux' relabel='yes'/>
...

Actual results:
After step 5, libvirt changes the guest xml on target host.

Expected results:
libvirt should not change the guest xml on target host if migration failed.

Comment 2 Jiri Denemark 2016-09-01 14:26:14 UTC

I was able to reproduce this bug with current libvirt, but 7.2 works just fine :(

Comment 4 Jiri Denemark 2016-09-08 15:08:13 UTC

Patches sent upstream for review: https://www.redhat.com/archives/libvir-list/2016-September/msg00279.html

Comment 5 Jiri Denemark 2016-09-08 21:25:09 UTC

This is now fixed upstream by

commit 66278d4bc38aecff6661c91ce9cd3fff26e54a91
Refs: v2.2.0-49-g66278d4
Author:     Jiri Denemark <jdenemar>
AuthorDate: Thu Sep 8 15:22:28 2016 +0200
Commit:     Jiri Denemark <jdenemar>
CommitDate: Thu Sep 8 22:25:22 2016 +0200

    qemu: Remove stale transient def when migration fails

    If a migration of a domain which is already defined on the destination
    host failed early (before we tried to start QEMU), we would forget to
    remove the incoming transient definition. Later on when someone starts
    the domain on the destination host, we will use the stale incoming
    definition and the persistent definition will just be ignored.

    https://bugzilla.redhat.com/show_bug.cgi?id=1368774

    Signed-off-by: Jiri Denemark <jdenemar>

commit 97a87333a0ac8b6b33bf4c45a7b1a526caa554cb
Refs: v2.2.0-48-g97a8733
Author:     Jiri Denemark <jdenemar>
AuthorDate: Thu Sep 8 15:16:58 2016 +0200
Commit:     Jiri Denemark <jdenemar>
CommitDate: Thu Sep 8 22:25:22 2016 +0200

    Add helper for removing transient definition

    The code for replacing domain's transient definition with the persistent
    one is repeated in several places and we'll need to add one more. Let's
    make a nice helper for it.

    Signed-off-by: Jiri Denemark <jdenemar>

Comment 8 yafu 2016-09-18 03:47:05 UTC

Reproduced with libvirt-2.0.0-5.el7.x86_64.
Steps are as comment 0.

Verify pass with libvirt-2.0.0-9.el7.x86_64.
1.Set this in source host qemu.conf and restart libvirtd service:
security_driver = "none"

2.Set this in target host qemu.conf and restart libvirtd service:
security_driver = "selinux"

3.Start a guest without seclabel in source, check the live xml of guest :
#virsh dumpxml rhel7.3
no seclabel

4.Migrate to target with option(success):
#virsh migrate rhel7.3 --live qemu+ssh://yafu-test/system --verbose

5.Try to migrate this guest back to source(fail and cause this issue):
# virsh migrate rhel7.3 --live qemu+ssh://test1/system --verbose
error: unsupported configuration: Unable to find security driver for model selinux

6.Then destroy target guest:
# virsh destroy rhel7.3
Domain rhel7.3 destroyed

7.Check the live xml of guest on source host, no seclabel added.
#virsh dumpxml rhel7.3
no seclabel

8.Start guest on source host again:
#virsh start rhel7.3
Domain mig1 started

Comment 10 errata-xmlrpc 2016-11-03 18:53:47 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHSA-2016-2577.html