docs: add known ipred-ctrl issue for speicfic cpu model #959
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Pull request overview
This PR adds documentation for a known upgrade issue related to the cpu-feature.node.kubevirt.io/ipred-ctrl=true CPU feature that appears during upgrades from v1.5.x to v1.6.x on specific Intel Xeon CPU models. The documentation provides workarounds for users before and after the upgrade.
Changes:
- Added a new section (§8) documenting the ipred-ctrl CPU feature issue during upgrades
- Updated subsequent section numbering (previous §8 becomes §9)
- Provided specific CPU models affected and multiple resolution options
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Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| docs/upgrade/v1-5-x-to-v1-6-x.md | Added new section 8 documenting ipred-ctrl CPU feature issue and renumbered subsequent sections |
| versioned_docs/version-v1.6/upgrade/v1-5-x-to-v1-6-x.md | Added identical documentation for v1.6 versioned docs |
| versioned_docs/version-v1.7/upgrade/v1-5-x-to-v1-6-x.md | Added identical documentation for v1.7 versioned docs |
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Signed-off-by: Jack Yu <jack.yu@suse.com>
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docs/upgrade/v1-5-x-to-v1-6-x.md
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| **After the upgrade:** | ||
| - Reboot the virtual machines. |
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if node-labeller was disabled, then VM's do not need to rebooted after the upgrade as selector labels matching cpu features will not have changed
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you're right, done!
Co-authored-by: Gaurav Mehta <gaurav.mehta@suse.com> Signed-off-by: Jack Yu <jack.yu@suse.com>
Signed-off-by: Jack Yu <jack.yu@suse.com>
ibrokethecloud
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Jan 22, 2026
| ### 8. Change in Default VLAN Behavior for Secondary Pod Interfaces | ||
| ### 8. `cpu-feature.node.kubevirt.io/ipred-ctrl=true` CPU Feature Appears During Upgrade | ||
| When upgrading from v1.5.x to v1.6.x, Harvester live migrates virtual machines to another node to complete the node upgrade. During this process, if your CPU model is in the following list, the `cpu-feature.node.kubevirt.io/ipred-ctrl=true` feature temporarily appears until the upgrade is complete. |
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Suggested change
| When upgrading from v1.5.x to v1.6.x, Harvester live migrates virtual machines to another node to complete the node upgrade. During this process, if your CPU model is in the following list, the `cpu-feature.node.kubevirt.io/ipred-ctrl=true` feature temporarily appears until the upgrade is complete. | |
| Harvester live migrates virtual machines to ensure zero downtime during node upgrades. If your cluster uses any of the following CPU models, you may notice a temporary feature flag (`cpu-feature.node.kubevirt.io/ipred-ctrl=true`) appear while the upgrade is in progress. |
| - Intel(R) Xeon(R) Gold 5418Y | ||
| - Intel(R) Xeon(R) Silver 4509Y | ||
| Because the `cpu-feature.node.kubevirt.io/ipred-ctrl=true` feature is no longer available after the upgrade, these virtual machines cannot be live migrated because of the mismatched node selector. |
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| Because the `cpu-feature.node.kubevirt.io/ipred-ctrl=true` feature is no longer available after the upgrade, these virtual machines cannot be live migrated because of the mismatched node selector. | |
| While this feature flag is automatically removed from nodes after the upgrade, the corresponding node selector is retained in the virtual machine configuration. This mismatch between the virtual machine's requirements and the node's labels causes subsequent live migrations to fail. |
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| To resolve this issue, use one of the following options: | ||
| **Before the upgrade:** | ||
| - **Option 1:** Configure a CPU model for the virtual machines using [this guideline](https://harvesterhci.io/kb/setup_common_cpu_model_for_vm_live_migration). | ||
| - **Option 2:** Stop the KubeVirt labeller by [adding the `node-labeller.kubevirt.io/skip-node` annotation to the nodes](https://kubevirt.io/user-guide/compute/virtual_hardware/#labeling-nodes-with-cpu-models-cpu-features-and-machine-types), and then remove the annotation after the upgrade completes. This option is more complex but useful if the virtual machines cannot be rebooted. For more information, see the [knowledge base article](https://harvesterhci.io/kb/troubleshooting_vm_scheduling_issues_nodeselector). |
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Suggested change
| To resolve this issue, use one of the following options: | |
| **Before the upgrade:** | |
| - **Option 1:** Configure a CPU model for the virtual machines using [this guideline](https://harvesterhci.io/kb/setup_common_cpu_model_for_vm_live_migration). | |
| - **Option 2:** Stop the KubeVirt labeller by [adding the `node-labeller.kubevirt.io/skip-node` annotation to the nodes](https://kubevirt.io/user-guide/compute/virtual_hardware/#labeling-nodes-with-cpu-models-cpu-features-and-machine-types), and then remove the annotation after the upgrade completes. This option is more complex but useful if the virtual machines cannot be rebooted. For more information, see the [knowledge base article](https://harvesterhci.io/kb/troubleshooting_vm_scheduling_issues_nodeselector). | |
| To resolve this issue, perform either of the following actions _before starting the upgrade_: | |
| - **Option 1:** [Configure a common CPU model](https://harvesterhci.io/kb/setup_common_cpu_model_for_vm_live_migration) for the virtual machines. | |
| - **Option 2:** Stop the KubeVirt labeller by [adding the `node-labeller.kubevirt.io/skip-node` annotation to the nodes](https://kubevirt.io/user-guide/compute/virtual_hardware/#labeling-nodes-with-cpu-models-cpu-features-and-machine-types), and then remove the annotation after the upgrade. While more complex, this option is useful if the virtual machines cannot be rebooted. For more information, see [Troubleshooting VM Live Migration Issues Caused by Node Selectors](https://harvesterhci.io/kb/troubleshooting_vm_scheduling_issues_nodeselector). |
ihcsim
approved these changes
Jan 22, 2026
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