fix(vmclass): use qemu64 CPU model for Discovery and Features types to improve AMD compatibility

[loktev-d]

Description

This PR changes the base CPU model for Discovery and Features CPU types from kvm64 to qemu64 to improve compatibility with AMD processors and because kvm64 is not recommended by qemu docs

Additionally, the svm CPU feature (AMD virtualization extension) is now marked as optional for Intel CPU compatibility (svm is required by default in qemu64).

Nested virtualization and migrations from kvm64 to qemu64 were tested on both Intel and AMD proccessors.

Why do we need it, and what problem does it solve?

We've encountered an issue where VMs with Nehalem VMClass fail to schedule in nested virtualization environments on AMD hosts. The problem occurs because:

1. The lahf_lm feature is required by Discovery VMClass
2. In nested virtualization on AMD processors, this feature is not exposed due to QEMU bug specific to kvm64 and AMD CPU
3. This causes the VMClass to remain in Pending state with no suitable nodes available

What is the expected result?

Checklist

• The code is covered by unit tests.
• e2e tests passed.
• Documentation updated according to the changes.
• Changes were tested in the Kubernetes cluster manually.

Changelog entries

section: vmclass
type: fix
summary: Use qemu64 CPU model for Discovery and Features types to fix nested virtualization on AMD hosts

Summary by Sourcery

Use qemu64 as the generic CPU model for Discovery and Features VMClasses and mark svm as an optional feature to improve AMD compatibility and nested virtualization support.

Bug Fixes:

• Switch the base CPU model for Discovery and Features types from kvm64 to qemu64 to resolve nested virtualization failures on AMD hosts
• Make the svm CPU feature optional when deriving features to maintain Intel compatibility

Build:

• Bump 3p-kubevirt component version to v1.3.1-v12n.14

Documentation:

• Update internal CPU model discovery documentation to reflect qemu64 usage

[deckhouse-BOaTswain]

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[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

This PR shifts the base CPU model from kvm64 to qemu64 for Discovery and Features VM classes to resolve nested virtualization issues on AMD hosts and adds optional handling for the AMD-specific svm feature, with accompanying documentation updates and a component version bump.

Entity relationship diagram for updated CPU model and features in VMClass

erDiagram
    VIRTUAL_MACHINE_CLASS {
        string Spec_CPU_Model
        string Spec_CPU_Type
        string[] Status_CpuFeatures_Enabled
    }
    CPU_FEATURE {
        string Name
        string Policy
    }
    VIRTUAL_MACHINE_CLASS ||--o{ CPU_FEATURE : has
    VIRTUAL_MACHINE_CLASS {
        string CPU_Model = "qemu64"
    }
    CPU_FEATURE {
        string Name = "svm"
        string Policy = "optional"
    }

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Class diagram for updated CPU model and feature handling in KVVM

classDiagram
    class KVVM {
        +SetCPUModel(class: VirtualMachineClass) error
    }
    class VirtualMachineClass {
        Spec: CPU
        Status: CpuFeatures
    }
    class CPU {
        Model: string
        Type: string
    }
    class CpuFeatures {
        Enabled: []string
    }
    class CPUFeature {
        Name: string
        Policy: string
    }
    KVVM --> VirtualMachineClass
    VirtualMachineClass --> CPU
    VirtualMachineClass --> CpuFeatures
    KVVM ..> CPUFeature : uses
    CPUFeature <|-- "svm (optional)"
    CPUFeature <|-- "invtsc (optional)"
    CPUFeature <|-- "other features (require)"

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File-Level Changes

Change	Details	Files
Use qemu64 as the default CPU model	Change GenericCPUModel constant from "kvm64" to "qemu64" Ensure Discovery/Features types pick up the updated GenericCPUModel	images/virtualization-artifact/pkg/controller/kvbuilder/kvvm.go
Mark "svm" CPU feature as optional	Add hasSvm flag when iterating enabled features Allocate slice with extra capacity and append optional "svm" if missing Set policy to "optional" for the added svm feature	images/virtualization-artifact/pkg/controller/kvbuilder/kvvm.go
Update documentation to reflect qemu64 model usage	Replace references to kvm64 with qemu64 in cpu_model_type_discovery.md Adjust patch instructions for cpu model nodeSelector accordingly	docs/internal/cpu_model_type_discovery.md
Bump kubevirt component version	Update 3p-kubevirt from v1.3.1-v12n.13 to v1.3.1-v12n.14	build/components/versions.yml

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