Bug 2216212
| Summary: | [RHEL9] Libvirt still requires a (DIMM) slot for virtio-mem devices | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 9 | Reporter: | David Hildenbrand <dhildenb> |
| Component: | libvirt | Assignee: | Peter Krempa <pkrempa> |
| libvirt sub component: | General | QA Contact: | liang cong <lcong> |
| Status: | VERIFIED --- | Docs Contact: | |
| Severity: | unspecified | ||
| Priority: | unspecified | CC: | jdenemar, jsuchane, lmen, mprivozn, pkrempa, virt-maint |
| Version: | 9.2 | Keywords: | Triaged |
| Target Milestone: | rc | ||
| Target Release: | --- | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
| Whiteboard: | |||
| Fixed In Version: | libvirt-9.5.0-0rc1.1.el9 | Doc Type: | If docs needed, set a value |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | Type: | Bug | |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | 9.5.0 |
| Embargoed: | |||
Fixed upstream:
commit 91856be29bb38e218c9bfe29ca08a9fef57dc64f
Author: Peter Krempa <pkrempa>
Date: Thu Jun 22 13:56:06 2023 +0200
qemuxml2(argv|xml)test: Add case for validating proper DIMM slot validation
Add a config where both DIMM and non-DIMM <memory> devices are used so
that it validates that only DIMMs require memory slots.
Signed-off-by: Peter Krempa <pkrempa>
Reviewed-by: Ján Tomko <jtomko>
commit e4b4765f4f2b24035402510263021bcf55bbea38
Author: Peter Krempa <pkrempa>
Date: Wed Jun 21 16:01:26 2023 +0200
conf: Allow omitting 'slots' attribute of <maxMemory>
Memory slots are required only for DIMM-like devices, but the maximum
memory address space is relevant also for other non-DIMM memory devices
such as virtio-mem. Allow configurations where no slots are added.
Signed-off-by: Peter Krempa <pkrempa>
Reviewed-by: Ján Tomko <jtomko>
commit e3ce39195c82c4e8f54ddad73e192d9317c9bb39
Author: Peter Krempa <pkrempa>
Date: Wed Jun 21 15:31:24 2023 +0200
qemu_domain: Properly validate count of memory slots
Memory slots are required only for DIMM-like devices, while other
devices defined via <memory> such as virtio-mem may use the PCI bus and
thus do not require/consume a memory slot.
Fix the validation code to calculate the required count of memory
devices only for DIMMs and NVDIMMs.
Signed-off-by: Peter Krempa <pkrempa>
Reviewed-by: Ján Tomko <jtomko>
commit a52c68443d12e0c9be98137150b7e9314d87dac6
Author: Peter Krempa <pkrempa>
Date: Wed Jun 21 16:31:46 2023 +0200
qemu_command: Always use modern syntax of '-m'
Specify the memory size by using '-m size=2048k' instead of just '-m 2'.
The new syntax is used when memory hotplug is enabled. To preserve
memory sizing, if memory hotplug is disabled the size is rounded down to
the nearest mebibyte.
Signed-off-by: Peter Krempa <pkrempa>
Reviewed-by: Ján Tomko <jtomko>
v9.4.0-71-g91856be29b
Pre-verify on upstream build libvirt v9.5.0-10-gcd4bdcb8cf
Test scenarios:
1.Virtio-mem cold plug with no slot
1.1 Define and start a guest with below config:
<maxMemory unit='KiB'>15242880</maxMemory>
<memory unit='KiB'>2097152</memory>
<currentMemory unit='KiB'>2097152</currentMemory>
...
<numa>
<cell id='0' cpus='0' memory='1048576' unit='KiB' />
<cell id='1' cpus='1' memory='1048576' unit='KiB' />
</numa>
...
<memory model='virtio-mem'>
<target>
<size unit='KiB'>2097152</size>
<node>0</node>
<block unit='KiB'>2048</block>
<requested unit='KiB'>1048576</requested>
</target>
</memory>
# virsh define vm1.xml
Domain 'vm1' defined from vm1.xml
# virsh start vm1
Domain 'vm1' started
1.2 Check the virsh dumpxml
# virsh dumpxml vm1 | xmllint --xpath '//devices/memory' -
<memory model="virtio-mem">
<target>
<size unit="KiB">2097152</size>
<node>0</node>
<block unit="KiB">2048</block>
<requested unit="KiB">1048576</requested>
<current unit="KiB">1048576</current>
<address base="0x100000000"/>
</target>
<alias name="virtiomem0"/>
<address type="pci" domain="0x0000" bus="0x07" slot="0x00" function="0x0"/>
</memory>
1.3 Attach a dimm memory device
# virsh attach-device vm1 dimm.xml
error: Failed to attach device from dimm.xml
error: unsupported configuration: count of memory devices requiring memory slots '1' exceeds slots count '0'
1.4 Attach another virtio-mem device
# virsh attach-device vm1 virtio.xml
Device attached successfully
2 Virtio-mem cold plug with 1 slot
2.1 Define and start a guest with below config:
<maxMemory unit='KiB' slots='1'>15242880</maxMemory>
<memory unit='KiB'>2097152</memory>
<currentMemory unit='KiB'>2097152</currentMemory>
...
<numa>
<cell id='0' cpus='0' memory='1048576' unit='KiB' />
<cell id='1' cpus='1' memory='1048576' unit='KiB' />
</numa>
...
<memory model='virtio-mem'>
<target>
<size unit='KiB'>2097152</size>
<node>0</node>
<block unit='KiB'>2048</block>
<requested unit='KiB'>1048576</requested>
</target>
</memory>
# virsh define vm1.xml
Domain 'vm1' defined from vm1.xml
# virsh start vm1
Domain 'vm1' started
2.2 Check the virsh dumpxml
# virsh dumpxml vm1 | xmllint --xpath '//devices/memory' -
<memory model="virtio-mem">
<target>
<size unit="KiB">2097152</size>
<node>0</node>
<block unit="KiB">2048</block>
<requested unit="KiB">1048576</requested>
<current unit="KiB">1048576</current>
<address base="0x100000000"/>
</target>
<alias name="virtiomem0"/>
<address type="pci" domain="0x0000" bus="0x07" slot="0x00" function="0x0"/>
</memory>
2.3 Attach a dimm memory device
# virsh attach-device vm1 dimm.xml
Device attached successfully
2.4 Attach a nvdimm memory device
# virsh attach-device vm1 nvdimm.xml
error: Failed to attach device from nvdimm.xml
error: unsupported configuration: count of memory devices requiring memory slots '2' exceeds slots count '1'
2.5 Attach another virtio-mem device
# virsh attach-device vm1 virtio.xml
Device attached successfully
Also test other scenarios, such as: dimm|nvdimm device with no|scarcy slot
Verified on build:
# rpm -q libvirt qemu-kvm
libvirt-9.5.0-3.el9.x86_64
qemu-kvm-8.0.0-9.el9.x86_64
Test scenarios:
1.Virtio-mem cold plug with no slot
1.1 Define and start a guest with below config:
<maxMemory unit='KiB'>15242880</maxMemory>
<memory unit='KiB'>2097152</memory>
<currentMemory unit='KiB'>2097152</currentMemory>
...
<numa>
<cell id='0' cpus='0' memory='1048576' unit='KiB' />
<cell id='1' cpus='1' memory='1048576' unit='KiB' />
</numa>
...
<memory model='virtio-mem'>
<target>
<size unit='KiB'>2097152</size>
<node>0</node>
<block unit='KiB'>2048</block>
<requested unit='KiB'>1048576</requested>
</target>
</memory>
# virsh define vm1.xml
Domain 'vm1' defined from vm1.xml
# virsh start vm1
Domain 'vm1' started
1.2 Check the virsh dumpxml
# virsh dumpxml vm1 | xmllint --xpath '//devices/memory' -
<memory model="virtio-mem">
<target>
<size unit="KiB">2097152</size>
<node>0</node>
<block unit="KiB">2048</block>
<requested unit="KiB">1048576</requested>
<current unit="KiB">1048576</current>
<address base="0x100000000"/>
</target>
<alias name="virtiomem0"/>
<address type="pci" domain="0x0000" bus="0x07" slot="0x00" function="0x0"/>
</memory>
1.3 Attach a dimm memory device
# virsh attach-device vm1 mem.xml
error: Failed to attach device from mem.xml
error: unsupported configuration: count of memory devices requiring memory slots '1' exceeds slots count '0'
1.4 Attach another virtio-mem device
# virsh attach-device vm1 virtio-mem.xml
Device attached successfully
2 Virtio-mem cold plug with 1 slot
2.1 Define and start a guest with below config:
<maxMemory unit='KiB' slots='1'>15242880</maxMemory>
<memory unit='KiB'>2097152</memory>
<currentMemory unit='KiB'>2097152</currentMemory>
...
<numa>
<cell id='0' cpus='0' memory='1048576' unit='KiB' />
<cell id='1' cpus='1' memory='1048576' unit='KiB' />
</numa>
...
<memory model='virtio-mem'>
<target>
<size unit='KiB'>2097152</size>
<node>0</node>
<block unit='KiB'>2048</block>
<requested unit='KiB'>1048576</requested>
</target>
</memory>
# virsh define vm1.xml
Domain 'vm1' defined from vm1.xml
# virsh start vm1
Domain 'vm1' started
2.2 Check the virsh dumpxml
# virsh dumpxml vm1 | xmllint --xpath '//devices/memory' -
<memory model="virtio-mem">
<target>
<size unit="KiB">2097152</size>
<node>0</node>
<block unit="KiB">2048</block>
<requested unit="KiB">1048576</requested>
<current unit="KiB">1048576</current>
<address base="0x100000000"/>
</target>
<alias name="virtiomem0"/>
<address type="pci" domain="0x0000" bus="0x07" slot="0x00" function="0x0"/>
</memory>
2.3 Attach a dimm and a virtio-mem memory device
# virsh attach-device vm1 virtio-mem.xml
Device attached successfully
# virsh attach-device vm1 mem.xml
Device attached successfully
2.4 Attach a nvdimm memory device
# virsh attach-device vm1 nvdimm.xml
error: Failed to attach device from nvdimm.xml
error: unsupported configuration: count of memory devices requiring memory slots '2' exceeds slots count '1'
2.5 Attach another virtio-mem device
# virsh attach-device vm1 virtio-mem.xml
Device attached successfully
Also test other scenarios, such as: dimm|nvdimm device with no|scarcy slot
|
Ever since QEMU commit 951f2269af2d ("vl: allow 'maxmem' without 'slot'") in 2018, QEMU has supported setting the "maxmem" option without the "slots" option. That was a preparation for virtio-pmem and virtio-mem devices, that do not consume DIMM/NVDIMM slots. Currently, in Libvirt, it's still required to reserve one slot for each virtio-mem and virtio-pmem device. For example, specifying two virtio-mem devices with only 1 slot: <maxMemory slots='1' unit='KiB'>16777216</maxMemory> results in "error: unsupported configuration: memory device count '2' exceeds slots count '1'" Specifying maxMemory without "slots" makes Libvirt angry: <maxMemory unit='KiB'>16777216</maxMemory> " error: XML document failed to validate against schema: Unable to validate doc against /usr/share/libvirt/schemas/domain.rng Extra element maxMemory in interleave Invalid sequence in interleave Element domain failed to validate content " virtio-mem (and virtio-pmem) devices don't require a DIMM slot. To increase usability, virtio-based memory devices should not require/consume a slot in Libvirt, and it should be possible to define a domain using the maxMemory option and no slots. Old QEMU versions will report an error like "invalid value of -m option: maxmem was specified, but no hotplug slots were specified".