Scaling Virtualization-Based Security for Hotpatching on Windows Arm64 and x64

Hotpatching’s promise — apply security fixes without forcing reboots — hinges on one non‑negotiable platform capability: Virtualization‑Based Security (VBS). For organizations preparing fleets for hotpatch delivery, enabling VBS at scale is the single most important operational task, and it’s also the step that creates the most surprises if not planned carefully. This feature‑length guide explains what VBS requires, how to enable and validate it across thousands of endpoints, how VBS ties into Hotpatch readiness (including the Arm64 specifics), and the practical rollout playbook that minimizes user disruption while controlling risk. Key configuration bits, registry keys, Intune CSPs, and one‑time platform changes are called out explicitly so IT teams can act with confidence.

Background: why VBS matters for hotpatching​

Virtualization‑Based Security creates an isolated runtime environment where sensitive services and kernel protections can run separate from the standard OS. That isolation is what enables Microsoft’s hotpatch model to safely apply in‑memory fixes to running code; without VBS, the platform cannot guarantee the integrity boundaries hotpatching relies on. Microsoft documented hotpatching as part of the broader update modernization work and has expanded support from x64 to Arm64, but the eligibility bar remains firm: VBS must be enabled and correctly configured for devices to receive hotpatches.
VBS also powers other security controls—Memory Integrity / Hypervisor‑Protected Code Integrity (HVCI) and Credential Guard—which are increasingly mandatory in regulated or high‑risk environments. Turning VBS on therefore improves baseline security posture as well as update flexibility, but it comes with dependencies on firmware, TPM, Secure Boot, and sometimes vendor drivers that need validation before enterprise‑wide rollouts.

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Overview: prerequisites and readiness checklist​

Before you enable VBS at scale, confirm the following prerequisites. These are the gating factors that will determine whether hotpatching becomes a simple policy flip or a multi‑week remediation program.

• Supported OS and build: For hotpatching on Arm64 and modern Windows clients, devices typically must run Windows 11 Enterprise 24H2 with the required baseline applied. Windows Server hotpatching has its own requirements (Windows Server 2025 and Azure Arc registration for some scenarios).
• Licensing and management: Eligible subscriptions (for client hotpatch) and enrollment in Microsoft Intune or Windows Autopatch are required for policy delivery and reporting.
• Firmware and platform security: Secure Boot and a functional TPM 2.0 are commonly required, and some VBS configurations require DMA protection settings on platforms that support it. Verify UEFI settings and update OEM firmware where necessary. (learn.microsoft.com, stigviewer.com)
• VBS prerequisites: CPU virtualization extensions and the system firmware must expose the features required by VBS (e.g., Mode‑Based Execution Control on Intel, Guest Mode Execute Trap on newer AMD SKUs).
• Arm64 special step: On Arm64 devices, Compiled Hybrid PE (CHPE) must be disabled once to enable hotpatching eligibility; this is a one‑time change requiring a reboot.

If any of the items above fail during an inventory pass, those devices remain ineligible for hotpatching and will continue to receive standard cumulative updates that require restarts. That’s an important operational distinction to call out early in planning.

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Technical prerequisites: what to validate in your estate​

1. Hardware and firmware checks​

Start with an automated inventory that captures CPU family, UEFI version, Secure Boot state, TPM version, and virtualization feature exposure. For large estates use existing endpoint management telemetry (SCCM, Intune, or third‑party UEM) to export these attributes and build a risk map.

• Minimum hardware: recent CPUs (post‑2018 for many Windows 11 features), TPM 2.0, UEFI with Secure Boot enabled. (learn.microsoft.com, theverge.com)
• Firmware: Some BIOS/UEFI versions ship with Secure Boot or DMA protection quirks; plan firmware upgrades in maintenance windows where needed.

2. Software and OS baseline​

Hotpatching is gated by specific build baselines. Devices must be at or above the minimum baseline Microsoft lists for hotpatch eligibility.

• Windows 11 Enterprise 24H2 builds starting from the baseline (examples noted in Microsoft guidance include builds such as 26100.2033 and later for initial hotpatch enablement). Confirm your devices match or exceed the required build.

3. Management plane and licensing​

Intune (or Windows Autopatch) is the supported mechanism for managing hotpatch policies. Validate:

• Intune enrollment and device group membership.
• Correct Windows edition licensing (Enterprise E3/E5, Microsoft 365 F3, Education A3/A5, or equivalent SKUs referenced by Microsoft).

4. VBS configuration and registry/Group Policy controls​

VBS can be enabled through the DeviceGuard CSP, GPO, or unattend settings for mass deployment. Key configuration entries you’ll use include:

• DeviceGuard CSP: ./Device/Vendor/MSFT/Policy/Config/DeviceGuard/EnableVirtualizationBasedSecurity — set to 1 to enable. Use this via Intune configuration profiles for scale.
• Unattend option: EnableVirtualizationBasedSecurity is also available for offline servicing/unattended setups.
• Platform security level: RequirePlatformSecurityFeatures CSP allows choosing Secure Boot or Secure Boot + DMA protection as required.

When enabling VBS by policy, expect at least one reboot in many cases to activate hypervisor launch and related services. Plan that step into your pilot’s cadence.

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Arm64 nuance: disabling CHPE (one-time, required)​

Arm64 hotpatching introduces a one‑time operational change you must apply before devices become eligible: disable Compiled Hybrid PE (CHPE). CHPE is a compatibility/performance layer that speeds x86 workloads on Arm64 by providing hybrid binaries; it is incompatible with the hotpatch in‑memory model and therefore must be turned off for hotpatching to proceed.
You can disable CHPE at scale by:

• Using the DisableCHPE CSP via Intune:
• ./Device/Vendor/MSFT/Policy/Config/Hotpatch/DisableCHPE = 1, then restart the device once.
• Or setting the registry key and rebooting:
• HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\HotPatchRestrictions = 1 (DWORD).

This is a one‑time setting. After the restart, Arm64 devices will be considered hotpatch‑eligible under the other prerequisites. However, disabling CHPE may change x86 emulation performance characteristics, so plan representative workload testing ahead of broad rollout. Community posts and IT blogs report real‑world cases where neglecting this step produced broken installs or instability — so do the restart and validate in pilot rings before expanding.

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Step‑by‑step: enable VBS at scale (recommended rollout)​

The following sequence reflects conservative, field‑tested practice for enterprise rollouts.

• Inventory and segment:
• Produce a complete inventory of candidate devices that captures OS build, firmware state, TPM, Secure Boot, CPU family, and whether devices are Arm64/x64. Flag devices that require firmware or OS baseline updates.
• Pilot — small, representative group:
• Create a pilot collection in Intune with devices representing common hardware and key line‑of‑business applications.
• For Arm64 pilot devices: apply the DisableCHPE CSP or registry change, reboot, and validate app performance.
• Configure VBS policy via Intune:
• Use the DeviceGuard CSP EnableVirtualizationBasedSecurity and optionally RequirePlatformSecurityFeatures to choose Secure Boot or Secure Boot + DMA mode depending on hardware capabilities.
• Set Memory Integrity (HVCI) enforcement if your workload supports it.
• Validate and test:
• Use Get-CimInstance -ClassName Win32_DeviceGuard or msinfo32.exe to confirm VBS status and which components are running (e.g., memory integrity, Credential Guard). Validate vendor drivers and EDR agents in the pilot ring.
• Expand in rings:
• Move from pilot → early adopter → broad deployment. Use Intune reporting and telemetry to track failures, reboots, or unexpected app regressions. Maintain a clear rollback plan for devices exhibiting incompatibility.
• Enable Hotpatch policy:
• Once VBS is validated, create or update your Windows Quality Update policy in Intune and set “When available, apply without restarting the device” to Allow. Target this to the hotpatch‑eligible groups. Monitor the first hotpatch cycle closely.

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Validation and telemetry: what to monitor after enabling VBS​

After enabling VBS, operational monitoring is critical because some regressions surface only under production workloads.

• VBS and HVCI state: Use Win32_DeviceGuard WMI class and msinfo32 for per‑device confirmation of the running state.
• Intune / Autopatch reports: track hotpatch compliance, installation errors, and device build metadata to confirm patches applied as hotpatches vs. baseline LCUs.
• Application and driver health: monitor crash rates, installation failures (MSI, drivers), backup and endpoint product compatibility. Community reports show third‑party drivers and backup agents are common friction points.
• Performance telemetry for Arm64: if you disabled CHPE, compare pre/post metrics for key x86 workloads; this validates whether disabling CHPE produces acceptable user experience metrics.

Also verify rollback and uninstall behavior in a lab: hotpatch uninstalls typically require a restart, and in some scenarios a full baseline LCU reinstall plus reboot is the supported recovery path. Make sure your incident runbooks reflect that reality—hotpatch is not a “no‑restart” safety net for remediation.

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Common pitfalls and how to avoid them​

• Skipping the CHPE disable step on Arm64. Consequence: silent hotpatch failures or system instability. Fix: implement an Intune remediation that detects Arm64 and sets HotPatchRestrictions = 1, then require a reboot. (cloudflow.be, techcommunity.microsoft.com)
• Missing firmware/UEFI requirements. Consequence: VBS shows “Available” but not “Running.” Fix: ensure Secure Boot and TPM are configured and OEM firmware is updated.
• Treating VBS as a pure policy flip. Consequence: untested third‑party drivers cause crashes in production. Fix: include critical ISV products in pilot validation and coordinate compatibility tests with vendors.
• Forgetting licensing or management prerequisites. Consequence: devices won’t be offered hotpatches even if VBS is enabled. Fix: verify enterprise SKUs and Intune enrollment before mass enabling.

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Security benefits — and operational tradeoffs​

Enabling VBS delivers strong security improvements: hardened kernel integrity, protection for credentials, and a smaller attack window when hotpatches reduce the time between disclosure and effective mitigation. These benefits are particularly compelling in high‑availability environments where forced reboots are costly.
At the same time, there are tradeoffs:

• Performance: VBS and HVCI can add overhead on older CPUs. Expect different performance impacts across device classes; quantify these in the pilot.
• Incompatibility surface: legacy drivers or security agents that aren’t VBS‑aware can cause instability. That’s why vendor coordination and phased testing are non‑optional.
• One‑time changes: changes like disabling CHPE on Arm64 are irreversible without administrative effort and require a plan to validate workloads afterward.

Balance these tradeoffs with the operational gains: fewer restarts, smaller update payloads, and faster time to protection. For many organizations those gains outweigh the costs; for others (specialized high‑performance workstations, legacy industrial endpoints) a selective opt‑in approach remains prudent.

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Practical checklist — quick reference for engineers​

• Inventory:
• Capture OS build, TPM, Secure Boot, CPU family, firmware version, and Intune enrollment state.
• Pilot actions:
• Choose pilot groups with representative hardware and critical apps.
• On Arm64 pilot devices, apply DisableCHPE via CSP or registry, reboot, validate.
• Apply DeviceGuard CSP EnableVirtualizationBasedSecurity = 1, choose platform security level.
• Validate with Get-CimInstance -ClassName Win32_DeviceGuard and msinfo32.exe.
• Monitoring:
• Track Intune quality update deployment status, EDR/backup agent behavior, and app crash telemetry.
• Rollback plan:
• Document uninstall and restart steps for hotpatches; test the full recovery path in lab before production rollout.

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Final analysis: readiness is achievable, but treat it as a program​

Enabling VBS at scale is not simply another settings change — it is a cross‑functional program that touches firmware, OS baselines, endpoint management, vendor compatibility, and user experience. When executed as a staged project with strong telemetry, the payoff is substantial: improved security posture, fewer disruptive reboots, and faster patching cycles via hotpatching. Microsoft’s hotpatch expansion (including Arm64 general availability) makes this the moment to invest in VBS readiness, but do so with operational discipline: inventory thoroughly, pilot widely, validate third‑party compatibility, and implement controlled ring rollouts.
A final caution: some quantitative claims you may read about adoption or “millions of devices” come from vendor telemetry and are useful directional signals, but they should be treated as vendor‑reported figures unless you can verify them in your own telemetry. Design your rollout around your estate realities, not the headline numbers.
The path to hotpatch readiness is clear: put VBS enablement at the top of your update modernization backlog, plan the Arm64 CHPE transition carefully, and use Intune’s CSPs and remediations to scale the configuration reliably. The result is a more secure, more available fleet—and in many environments, a real reduction in the operational cost of keeping devices up to date.

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Source: Microsoft - Message Center Built to last