[libvirt] [PATCH 0/2] Fix virsh save-restore/migration with memory hotplug.
Virsh restore/migration fails on a VM which has gone
through a series of memory attach and detach where
the sequence of detach is random(not in LIFO order).
With memory hotplug, the dimms are looked up
using the object-id and so, the restore/migration
fails because the qemu command that gets generated
has memdev and id values which wouldn't exist for
the given slotid.
This patch ensures that the source and destination would
always have same memdev-objectid-slotid values.
Steps to hit the issue:
1. Hot add two memory dimms twice.
virsh attach-device VMName memHotplug.xml --live
virsh attach-device VMName memHotplug.xml --live
2. cat memHotplug.xml
<memory model='dimm' >
<target>
<size unit='MiB'>128</size>
<node>0</node>
</target>
</memory>
3. Now hot unplug the first memory module attached.
virsh detach-device VMName detach.xml --live
4. cat detach.xml
<memory model='dimm'>
<target>
<size unit='MiB'>128</size>
<node>0</node>
</target>
<alias name='dimm0'/>
<address type='dimm' slot='0' base='0x100000000'/>
</memory>
5.Save the VM and then restore. Restore fails..
virsh save VMName ./VMName.vmsav
virsh restore ./VMName.vmsav
Error: Unknown ramblock "memdimm1".
6. Example qemu log without current patch.
dimm,node=0,memdev=memdimm0,id=dimm0,slot=1,addr=4429185024 -object
memory-backend-ram,id=memdimm1,size=134217728 -device
pc-dimm,node=0,memdev=memdimm1,id=dimm1,slot=2,addr=4563402752 -object
memory-backend-ram,id=memdimm2,size=134217728 -device
pc-dimm,node=0,memdev=memdimm2,id=dimm2,slot=3,addr=4697620480 -object
memory-backend-ram,id=memdimm3,size=134217728 -device
pc-dimm,node=0,memdev=memdimm3,id=dimm3,slot=4,addr=4831838208 -object
memory-backend-ram,id=memdimm4,size=134217728 -device
pc-dimm,node=0,memdev=memdimm4,id=dimm4,slot=5,addr=4966055936
7. With the current patch we have kept the dimm name as dimmX where X=slot number.In such
a
case the memdev and id generated are always correct w.r.t the slotid and the virsh
restore/
migrate succeeds.
dimm,node=0,memdev=memdimm1,id=dimm1,slot=1,addr=4429185024 -object
memory-backend-ram,id=memdimm2,size=134217728 -device
pc-dimm,node=0,memdev=memdimm2,id=dimm2,slot=2,addr=4563402752 -object
memory-backend-ram,id=memdimm3,size=134217728 -device
pc-dimm,node=0,memdev=memdimm3,id=dimm3,slot=3,addr=4697620480 -object
memory-backend-ram,id=memdimm4,size=134217728 -device
pc-dimm,node=0,memdev=memdimm4,id=dimm4,slot=4,addr=4831838208 -object
memory-backend-ram,id=memdimm5,size=134217728 -device
pc-dimm,node=0,memdev=memdimm5,id=dimm5,slot=5,addr=4966055936
Nitesh Konkar (2):
qemu_alias:Set dimm alias name to dimmX where X=slot number.
tests/qemuxml2argvdata:Add a testcase
src/qemu/qemu_alias.c | 51 +++++++++---
.../qemuxml2argv-memory-hotplug-dimm-alias.args | 35 ++++++++
.../qemuxml2argv-memory-hotplug-dimm-alias.xml | 94 ++++++++++++++++++++++
tests/qemuxml2argvtest.c | 2 +
4 files changed, 172 insertions(+), 10 deletions(-)
create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-memory-hotplug-dimm-alias.args
create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-memory-hotplug-dimm-alias.xml
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1.9.3