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Bug 1449595 - Check CPU cache for ABI stability
Summary: Check CPU cache for ABI stability
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: libvirt
Version: 7.4
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Jiri Denemark
QA Contact: zhe peng
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2017-05-10 10:49 UTC by Jiri Denemark
Modified: 2017-08-02 01:32 UTC (History)
4 users (show)

Fixed In Version: libvirt-3.2.0-5.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)


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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 Jiri Denemark 2017-05-10 10:49:35 UTC 
Description of problem:

It is possible to change CPU cache settings during migration (via the pre-migration hook or a custom XML) and libvirt won't complain about ABI incompatibility.

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

libvirt-3.2.0-4.el7

How reproducible:

100%

Steps to Reproduce:
1. Start a new domain DOM
2. virsh dumpxml --migratable DOM >dom.xml
3. edit dom.xml and change CPU cache settings
4. virsh migrate --xml dom.xml DOM URI

Actual results:

Libvirt will successfully migrate the domain even though the CPU cache is different.

Expected results:

Libvirt should complain about target CPU cache not matching source.

Additional info:

See bug 1428952 which added the ability to set CPU cache.
Comment 1 Jiri Denemark 2017-05-10 10:59:12 UTC 
Fixed upstream by

commit 1e9cf6e09ce242c94731bd21707dd3bcd41f854f
Refs: v3.3.0-21-g1e9cf6e09
Author:     Jiri Denemark <jdenemar>
AuthorDate: Tue May 9 16:03:19 2017 +0200
Commit:     Jiri Denemark <jdenemar>
CommitDate: Wed May 10 11:20:07 2017 +0200

    conf: Check CPU cache for ABI stability

    Signed-off-by: Jiri Denemark <jdenemar>
    Reviewed-by: Daniel P. Berrange <berrange>
Comment 4 zhe peng 2017-06-13 03:32:01 UTC 
verify with build:
libvirt-3.2.0-9.virtcov.el7.x86_64

step:
1. start a dom w/o cpu config
2.# virsh dumpxml --migratable rhel7 > dom.xml
3. edit xml and change CPU cache
 <cpu mode='host-model'>
    <model fallback='allow'/>
    <cache level='3' mode='emulate'/>
  </cpu>
4.do migrate
# virsh migrate rhel7 --xml dom.xml qemu+ssh://$targethost/system --verbose
error: unsupported configuration: Target CPU does not match source

5.edit xml 
disable + host-model
  <cpu mode='host-model' check='partial'>
    <model fallback='allow'/>
    <cache mode='disable'/>
  </cpu>
host-passthrough + l3
<cpu mode='host-passthrough' check='partial'>
    <cache level='3' mode='emulate'/>
  </cpu>
host-passthrough + passthrough
  <cpu mode='host-passthrough' check='partial'>
    <cache mode='passthrough'/>
  </cpu>
host-passthrough + disable
<cpu mode='host-passthrough' check='partial'>
    <cache mode='disable'/>
  </cpu>
all get error 
error: unsupported configuration: Target CPU does not match source

6. prepare a guest with cpu custom model
...
<cpu mode='custom' match='exact' check='full'>
    <model fallback='forbid'>cpu64-rhel6</model>
    <feature policy='require' name='x2apic'/>
    <feature policy='require' name='hypervisor'/>
    <feature policy='require' name='abm'/>
    <feature policy='disable' name='sse4a'/>
  </cpu>
...
repeat step 2 3
# virsh migrate rhel7 --xml dom.xml qemu+ssh://$targethost/system --verbose
error: unsupported configuration: Target CPU model Skylake-Client does not match source cpu64-rhel6

7. prepare a guest with cpu host model
start the guest
<cpu mode='custom' match='exact' check='full'>
    <model fallback='forbid'>Skylake-Client</model>
    <vendor>Intel</vendor>
    <feature policy='require' name='ss'/>
    <feature policy='require' name='hypervisor'/>
    <feature policy='require' name='tsc_adjust'/>
    <feature policy='require' name='clflushopt'/>
    <feature policy='require' name='pdpe1gb'/>
  </cpu>
repeat step 2 3
# virsh migrate rhel7 --xml dom.xml qemu+ssh://$targethost/system --verbose
error: unsupported configuration: Target CPU cache does not match source

move to verified.
Comment 5 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 6 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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