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Bug 1450349 - No ABI check for /memoryBacking/[source|access|allocation] in guest xml
Summary: No ABI check for /memoryBacking/[source|access|allocation] in guest xml
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: libvirt
Version: 7.4
Hardware: All
OS: Linux
medium
medium
Target Milestone: rc
: ---
Assignee: Michal Privoznik
QA Contact: Luyao Huang
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2017-05-12 10:13 UTC by Luyao Huang
Modified: 2017-08-02 01:32 UTC (History)
4 users (show)

Fixed In Version: libvirt-3.2.0-9.el7
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2017-08-02 00:08:25 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHEA-2017:1846 0 normal SHIPPED_LIVE libvirt bug fix and enhancement update 2017-08-01 18:02:50 UTC

Description Luyao Huang 2017-05-12 10:13:06 UTC 
Description of problem:

No ABI check for /memoryBacking/[source|access|allocation] in guest xml

Version-Release number of selected component (if applicable):
libvirt-3.2.0-4.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1.prepare a guest with xml like this:

  <memoryBacking>
    <source type='file'/>
    <access mode='private'/>
    <allocation mode='ondemand'/>
  </memoryBacking>


2.start guest and save this guest:

# virsh start r7
Domain r7 started

# virsh managedsave r7

Domain r7 state saved by libvirt

3. use save-image-edit to change the source type or access mode or allocation mode:
# virsh save-image-edit /var/lib/libvirt/qemu/save/r7.save 
change to:
  <memoryBacking>
    <source type='anonymous'/>
    <access mode='private'/>
  </memoryBacking>
State file /var/lib/libvirt/qemu/save/r7.save edited.

4. try to restore guest:

# virsh start r7
error: Failed to start domain r7
error: operation failed: job: unexpectedly failed


5. check guest log

2017-05-12T10:10:30.322768Z qemu-kvm: Unknown ramblock "/objects/ram-node0", cannot accept migration
2017-05-12T10:10:30.322799Z qemu-kvm: error while loading state for instance 0x0 of device 'ram'
2017-05-12T10:10:30.323204Z qemu-kvm: load of migration failed: Invalid argument


Actual results:

No ABI check for /memoryBacking/[source|access|allocation] in guest xml

Expected results:

Libvirt should not allow this change since it will effect the guest resource, and won't pass qemu ABI

Additional info:
Comment 2 Michal Privoznik 2017-05-18 08:06:31 UTC 
Patch proposed upstream:

https://www.redhat.com/archives/libvir-list/2017-May/msg00626.html
Comment 3 Michal Privoznik 2017-05-24 14:46:32 UTC 
Another attempt:

https://www.redhat.com/archives/libvir-list/2017-May/msg00939.html
Comment 4 Michal Privoznik 2017-06-05 07:37:51 UTC 
Moving to POST:

http://post-office.corp.redhat.com/archives/rhvirt-patches/2017-June/msg00056.html


During upstream review it turned out that @access and @allocation has no effect on guest ABI. Therefore the only thing that this patch set checks is @source.
Comment 6 Luyao Huang 2017-06-08 06:22:30 UTC 
Verify this bug with libvirt-3.2.0-9.el7.x86_64:

1. start a guest use file as memory backend:

# virsh dumpxml r7 
...
  <memoryBacking>
    <source type='file'/>
    <access mode='shared'/>
  </memoryBacking>
...

2. managedsave guest:

# virsh managedsave r7 

Domain r7 state saved by libvirt

3. use save-image-edit try to change source type:

# virsh save-image-edit /var/lib/libvirt/qemu/save/r7.save 
error: unsupported configuration: Target memoryBacking source 'anonymous' doesn't match source memoryBacking source'file'
Failed. Try again? [y,n,f,?]:
Comment 7 errata-xmlrpc 2017-08-02 00:08:25 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://access.redhat.com/errata/RHEA-2017:1846
Comment 8 errata-xmlrpc 2017-08-02 01:32:35 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://access.redhat.com/errata/RHEA-2017:1846
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