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Bug 1724980 - The qemu command line for nvdimm is wrong
Summary: The qemu command line for nvdimm is wrong
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: libvirt
Version: 7.7
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: 7.7
Assignee: Michal Privoznik
QA Contact: Jing Qi
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2019-06-28 07:58 UTC by Fangge Jin
Modified: 2020-03-31 19:59 UTC (History)
7 users (show)

Fixed In Version: libvirt-4.5.0-24.el7
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2020-03-31 19:58:29 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)
vm xml (16.36 KB, text/html)
2019-06-28 07:58 UTC, Fangge Jin 		no flags Details
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Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2020:1094 0 None None None 2020-03-31 19:59:23 UTC

Description Fangge Jin 2019-06-28 07:58:50 UTC 
Created attachment 1585481 [details]
vm xml

Description of problem:
The qemu command line for nvdimm is wrong

Version-Release number of selected component (if applicable):
libvirt-4.5.0-23.virtcov.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1.Prepare a vm with nvdimm device:
...
  <memoryBacking>
    <hugepages>
      <page size='2048' unit='KiB'/>
    </hugepages>
    <discard/>
    <access mode='shared'/>
    <allocation mode='immediate'/>
    <nosharepages/>
  </memoryBacking>
...
<devices>
...
    <memory model='nvdimm'>
      <source>
        <path>/tmp/nvdimm</path>
      </source>
      <target>
        <size unit='KiB'>524288</size>
        <node>1</node>
        <label>
          <size unit='KiB'>128</size>
        </label>
      </target>
      <address type='dimm' slot='1'/>
    </memory>

2.Start vm

3.Check qemu command line, it didn't use the path "/tmp/nvdimm', it used "/dev/hugepages/libvirt/qemu/2-rhel7.6" instead:
...
-machine pc-i440fx-rhel7.6.0,accel=kvm,usb=off,vmport=on,dump-guest-core=off,mem-merge=off,nvdimm=on \
-object memory-backend-file,id=memnvdimm1,prealloc=yes,mem-path=/dev/hugepages/libvirt/qemu/2-rhel7.6,share=yes,size=536870912,host-nodes=0,policy=bind \
-device nvdimm,node=1,label-size=131072,memdev=memnvdimm1,id=nvdimm1,slot=1 \

Actual results:
The qemu command line for nvdimm device uses mem-path=/dev/hugepages/libvirt/qemu/2-rhel7.6

Expected results:
The qemu command line for nvdimm device should use mem-path=/tmp/nvdimm

Additional info:
Comment 2 Fangge Jin 2019-06-28 09:02:14 UTC 
Hi Jaroslav

This bug can not be reproduced on RHEL8.0-av:
libvirt-5.0.0-11.module+el8.0.1+3459+e357ef2f.x86_64
Comment 3 Michal Privoznik 2019-06-28 15:20:51 UTC 
(In reply to Fangge Jin from comment #2)
> Hi Jaroslav
> 
> This bug can not be reproduced on RHEL8.0-av:
> libvirt-5.0.0-11.module+el8.0.1+3459+e357ef2f.x86_64

This is because it was fixed in v4.7.0-rc1~197. Moving back to RHEL-7.7 and to POST:

http://post-office.corp.redhat.com/archives/rhvirt-patches/2019-June/msg01047.html
Comment 6 Jing Qi 2019-08-19 03:27:08 UTC 
Verified with libvirt-4.5.0-24.el7.x86_64.rpm & qemu-kvm-rhev-2.12.0-18.el7_6.3.x86_64
Domain with below xml  -
<memoryBacking>
    <hugepages/>
    <source type='file'/>
    <allocation mode='immediate'/>
</memoryBacking>
....
<memory model='nvdimm'>
      <source>
        <path>/tmp/nvdimm</path>
      </source>
      <target>
        <size unit='KiB'>524288</size>
        <node>0</node>
        <label>
          <size unit='KiB'>128</size>
        </label>
      </target>
      <address type='dimm' slot='2'/>
    </memory>
# virsh start avocado-vt-vm-numa0

Check the qemu cmd line, id=memnvdimm2,prealloc=yes,mem-path=/tmp/nvdimm      

 ps -fe |grep qemu-kvm |grep /tmp
qemu      23578      1 99 23:26 ?        00:00:31 /usr/libexec/qemu-kvm -name guest=avocado-vt-vm-numa0,debug-threads=on -S -object secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-9-avocado-vt-vm-numa0/master-key.aes -machine pc-i440fx-rhel7.5.0,accel=kvm,usb=off,vmport=on,dump-guest-core=off,mem-merge=off,nvdimm=on,kernel_irqchip=split -cpu qemu64,+kvm_pv_unhalt,pmu=off -bios /usr/share/seabios/bios.bin -m size=1048576k,slots=8,maxmem=134217728k -mem-prealloc -realtime mlock=off -smp 3,sockets=3,cores=1,threads=1 -object memory-backend-file,id=ram-node0,prealloc=yes,mem-path=/dev/hugepages/libvirt/qemu/9-avocado-vt-vm-numa0,discard-data=yes,share=yes,size=1073741824,host-nodes=0,policy=bind -numa node,nodeid=0,cpus=0-2,memdev=ram-node0 -object memory-backend-file,id=memdimm0,prealloc=yes,mem-path=/dev/hugepages/libvirt/qemu/9-avocado-vt-vm-numa0,discard-data=yes,share=no,size=536870912,host-nodes=0,policy=bind -device pc-dimm,node=0,memdev=memdimm0,id=dimm0,slot=0,addr=4294967296 -object memory-backend-file,id=memdimm1,prealloc=yes,mem-path=/dev/hugepages/libvirt/qemu/9-avocado-vt-vm-numa0,discard-data=yes,share=yes,size=536870912,host-nodes=0,policy=bind -device pc-dimm,node=0,memdev=memdimm1,id=dimm1,slot=1,addr=4831838208 -object memory-backend-file,id=memnvdimm2,prealloc=yes,mem-path=/tmp/nvdimm,share=yes,size=536870912,host-nodes=0,policy=bind -device nvdimm,node=0,label-size=131072,memdev=memnvdimm2,id=nvdimm2,slot=2 -uuid 431a12a2-c8d3-4234-9558-ab233bb93198
Comment 7 Jing Qi 2020-02-04 09:38:57 UTC 
Verified with libvirt-4.5.0-32.virtcov.el7.x86_64 & qemu-kvm-rhev-2.12.0-43.el7.x86_64 by using the steps in Comment 6 and passed.
Comment 9 errata-xmlrpc 2020-03-31 19:58:29 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/RHBA-2020:1094
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