The fix is provided to settle with maxmemory value changes after performing hotplug operation. by TasmiyaNalatwad · Pull Request #6695 · autotest/tp-libvirt

TasmiyaNalatwad · 2025-12-01T06:57:29Z

The fix is provided to settle with maxmemory value changes after perorming hotplug operation when hugepages are included.

When you add a memory device (model="dimm"), libvirt ensures the max memory is aligned to memory block size (usually 64 MiB or 128 MiB). This is normal behavior for hotplug support.

I have hugepages assigned with 2048kib in the test and test fails when validating max_memory value before and after hotplug operation was performed. The max_memory value had changed after hotplug and the test was failing. After analyses i found that max_memory value got increased by 64Mib to align to memory block size. This is because hotplugging a memory DIMM changes the VM’s runtime maximum memory, and libvirt automatically adjusts internally.

Before Fix :

python3 avocado-setup.py --run-suite guest_memory-bck --guest-os RHEL.8.devel.ppc64le --only-filter 'virtio_scsi virtio_net qcow2' --no-download 01:53:40 INFO : Env Config: /home/tests/config/wrapper/env.conf 01:53:40 INFO : No Run Config: /home/tests/config/wrapper/no_run_tests.conf 01:53:40 WARNING : Overriding user setting and enabling kvm bootstrap as guest tests are requested 01:53:40 INFO : Check for environment 01:53:42 INFO : Creating temporary mux dir 01:53:42 INFO : 01:53:42 INFO : Running Guest Tests Suite memory-bck 01:53:42 INFO : Running: /usr/local/bin/avocado run --vt-type libvirt --vt-config /home/tests/data/avocado-vt/backends/libvirt/cfg/memory-bck.cfg --force-job-id 063573451849b1d2cb4411af32b516449891b8ce --job-results-dir /home/tests/results --vt-only-filter "virtio_scsi virtio_net qcow2 RHEL.8.devel.ppc64le" JOB ID : 063573451849b1d2cb4411af32b516449891b8ce JOB LOG : /home/tests/results/job-2025-12-01T01.53-0635734/job.log (1/5) io-github-autotest-qemu.unattended_install.import.import.default_install.aio_native: STARTED (1/5) io-github-autotest-qemu.unattended_install.import.import.default_install.aio_native: PASS (41.19 s) (2/5) type_specific.io-github-autotest-libvirt.libvirt_mem.positive_test.hugepages.no_numatune.cold_plug: STARTED (2/5) type_specific.io-github-autotest-libvirt.libvirt_mem.positive_test.hugepages.no_numatune.cold_plug: FAIL: Found unmatched memory setting from domain xml (30.50 s) (3/5) type_specific.io-github-autotest-libvirt.libvirt_mem.positive_test.hugepages.no_numatune.cold_plug_discard: STARTED (3/5) type_specific.io-github-autotest-libvirt.libvirt_mem.positive_test.hugepages.no_numatune.cold_plug_discard: FAIL: Found unmatched memory setting from domain xml (30.78 s) (4/5) type_specific.io-github-autotest-libvirt.libvirt_mem.positive_test.hugepages.no_numatune.discard: STARTED (4/5) type_specific.io-github-autotest-libvirt.libvirt_mem.positive_test.hugepages.no_numatune.discard: FAIL: Found unmatched memory setting from domain xml (53.92 s) (5/5) io-github-autotest-libvirt.remove_guest.without_disk: STARTED (5/5) io-github-autotest-libvirt.remove_guest.without_disk: PASS (4.12 s) RESULTS : PASS 2 | ERROR 0 | FAIL 3 | SKIP 0 | WARN 0 | INTERRUPT 0 | CANCEL 0 JOB HTML : /home/tests/results/job-2025-12-01T01.53-0635734/results.html JOB TIME : 180.80 s

After Fix :

`python3 avocado-setup.py --run-suite guest_memory-bck --guest-os RHEL.8.devel.ppc64le --only-filter 'virtio_scsi virtio_net qcow2' --no-download
00:55:01 INFO : Env Config: /home/tests/config/wrapper/env.conf
00:55:01 INFO : No Run Config: /home/tests/config/wrapper/no_run_tests.conf
00:55:01 WARNING : Overriding user setting and enabling kvm bootstrap as guest tests are requested
00:55:01 INFO : Check for environment
00:55:02 INFO : Creating temporary mux dir
00:55:02 INFO :
00:55:02 INFO : Running Guest Tests Suite memory-bck
00:55:02 INFO : Running: /usr/local/bin/avocado run --vt-type libvirt --vt-config /home/tests/data/avocado-vt/backends/libvirt/cfg/memory-bck.cfg --force-job-id 3481891a8148cd06f953d1fddabc678182d7979f --job-results-dir /home/tests/results --vt-only-filter "virtio_scsi virtio_net qcow2 RHEL.8.devel.ppc64le"
JOB ID : 3481891a8148cd06f953d1fddabc678182d7979f
JOB LOG : /home/tests/results/job-2025-12-01T00.55-3481891/job.log
(1/5) io-github-autotest-qemu.unattended_install.import.import.default_install.aio_native: STARTED
(1/5) io-github-autotest-qemu.unattended_install.import.import.default_install.aio_native: PASS (39.91 s)
(2/5) type_specific.io-github-autotest-libvirt.libvirt_mem.positive_test.hugepages.no_numatune.cold_plug: STARTED
(2/5) type_specific.io-github-autotest-libvirt.libvirt_mem.positive_test.hugepages.no_numatune.cold_plug: PASS (69.05 s)
(3/5) type_specific.io-github-autotest-libvirt.libvirt_mem.positive_test.hugepages.no_numatune.cold_plug_discard: STARTED
(3/5) type_specific.io-github-autotest-libvirt.libvirt_mem.positive_test.hugepages.no_numatune.cold_plug_discard: PASS (69.66 s)
(4/5) type_specific.io-github-autotest-libvirt.libvirt_mem.positive_test.hugepages.no_numatune.discard: STARTED
(4/5) type_specific.io-github-autotest-libvirt.libvirt_mem.positive_test.hugepages.no_numatune.discard: PASS (93.14 s)
(5/5) io-github-autotest-libvirt.remove_guest.without_disk: STARTED
(5/5) io-github-autotest-libvirt.remove_guest.without_disk: PASS (4.20 s)
RESULTS : PASS 5 | ERROR 0 | FAIL 0 | SKIP 0 | WARN 0 | INTERRUPT 0 | CANCEL 0
JOB HTML : /home/tests/results/job-2025-12-01T00.55-3481891/results.html
JOB TIME : 295.56 s
01:00:00 INFO :
01:00:00 INFO : Summary of test results can be found below:
TestSuite TestRun Summary

guest_memory-bck Run Successfully executed
/home/tests/results/job-2025-12-01T00.55-3481891/job.log
| PASS 5 || CANCEL 0 || ERRORS 0 || FAILURES 0 || SKIP 0 || WARN 0 || INTERRUPT 0 |`

Summary by CodeRabbit

Tests
- Adjusted memory validation tests to allow runtime memory growth on ppc64 architectures (e.g., with hugepages) while keeping strict equality checks for other architectures.

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coderabbitai · 2025-12-01T06:57:40Z

Walkthrough

A conditional check is added to an assertion in the check_dom_xml function in libvirt/tests/src/libvirt_mem.py. The assertion that compared max_mem_rt to xml_max_mem_rt now allows max_mem_rt <= xml_max_mem_rt for architectures containing "ppc64", while preserving max_mem_rt == xml_max_mem_rt for other architectures. A comment explaining the PPC64-specific rationale was added.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Single file (libvirt/tests/src/libvirt_mem.py) and single function changed
Small conditional logic addition; low cognitive load
Areas to check:
- Correct detection of PPC64 architectures (string containment)
- Comment accuracy and whether additional test coverage is needed for PPC64 behavior

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✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title describes max memory value changes after hotplug, which directly relates to the primary change: adjusting test assertions for architecture-specific max memory behavior.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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TasmiyaNalatwad · 2025-12-01T07:00:26Z

@chloerh Would you please have a look at this PR and help me with review comments. Thanks for your time and support.

coderabbitai

Actionable comments posted: 1

🧹 Nitpick comments (1)

libvirt/tests/src/libvirt_mem.py (1)
243-245: Clarify comment: Issue is not hugepage-specific.

The comment associates this behavior with hugepages, but according to the PR description, libvirt aligns max memory to the memory block size (64 MiB or 128 MiB) during any memory hotplug operation, not just when hugepages are used. Consider rephrasing for accuracy.
-            # for arch ppc64 and hugepages, the run time max memory grows and never shrinks.
-            # libvirt rounded max memory boundaries to align with hugepage requirements
+            # On ppc64, libvirt aligns max memory to memory block size (typically 64/128 MiB)
+            # during memory hotplug operations, which may increase the runtime max memory value.

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TasmiyaNalatwad · 2026-09-15T12:41:24Z

@chloerh Would you please have a look at this PR and help me with review comments. Thanks for your time and support.

crobinso · 2026-09-15T16:38:52Z

@TasmiyaNalatwad there are still open review comments from coderabbit. can you address those, or comment and mark them resolved if you disagree. after that I can do a review if you ping me

…orming hotplug operation when hugepages are included. When you add a memory device (model="dimm"), libvirt ensures the max memory is aligned to memory block size (usually 64 MiB or 128 MiB). This is normal behavior for hotplug support. I have hugepages assigned with 2048kib in the test and test fails when validating max_memory value before and after hotplug operation was performed. The max_memory value had changed after hotplug and the test was failing. After analyses i found that max_memory value got increased by 64Mib to align to memory block size. This is because hotplugging a memory DIMM changes the VM’s runtime maximum memory, and libvirt automatically adjusts <maxMemory> internally. Signed-off-by: Tasmiya Nalatwad <Tasmiya.Nalatwad@ibm.com>

TasmiyaNalatwad · 2026-09-16T08:48:07Z

@TasmiyaNalatwad there are still open review comments from coderabbit. can you address those, or comment and mark them resolved if you disagree. after that I can do a review if you ping me

@crobinso Thanks for the time. I have taken care of the review comments from coderabbitai. Requesting to p
lease help me with the PR review. TIA

TasmiyaNalatwad changed the title ~~The fix is provided to settle with maxmemory value changes after perf…~~ The fix is provided to settle with maxmemory value changes after perorming hotplug operation when hugepages are included. Dec 1, 2025

coderabbitai Bot reviewed Dec 1, 2025

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Comment thread libvirt/tests/src/libvirt_mem.py

TasmiyaNalatwad force-pushed the fix_libvirt_maxmem_support_ppc64 branch from b6edca4 to 4e0327f Compare December 1, 2025 07:17

TasmiyaNalatwad changed the title ~~The fix is provided to settle with maxmemory value changes after perorming hotplug operation when hugepages are included.~~ The fix is provided to settle with maxmemory value changes after perorming hotplug operation. Dec 1, 2025

TasmiyaNalatwad mentioned this pull request Dec 2, 2025

The fix is provided to settle with maxmemory value changes after performing hotplug operation when hugepages are included. lop-devops/tp-libvirt#8

Open

TasmiyaNalatwad changed the title ~~The fix is provided to settle with maxmemory value changes after perorming hotplug operation.~~ The fix is provided to settle with maxmemory value changes after performing hotplug operation. Aug 17, 2026

TasmiyaNalatwad force-pushed the fix_libvirt_maxmem_support_ppc64 branch from 4e0327f to a0c658e Compare September 16, 2026 08:46

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The fix is provided to settle with maxmemory value changes after performing hotplug operation. - #6695

The fix is provided to settle with maxmemory value changes after performing hotplug operation.#6695
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