IOMMU detection with vanguard messed up after the most recent windows update

Question

After the most recent windows update on 3/3, I have been unable to play VALORANT, as IOMMU detection has been very strange. I am currently investing FACEIT anticheat to see if it is just an interaction between Windows and Riot? Or an IOMMU issue overall. Does anyone have any help?

Answer 1

Hi Sean Lee,

Welcome to the Microsoft Q&A forum.

Based on what you described, this behavior is commonly related to how Windows security and virtualization features (such as IOMMU, Core Isolation, or the hypervisor) interact with kernel‑level anti‑cheat software. After updates, some of these settings may change automatically, which can affect game launch behavior. And testing with another anti‑cheat (such as FACEIT) is a good way to confirm whether the behavior is system‑wide or application‑specific.

Here are some additional checking steps that you can consider trying:

1, Turn off Memory Integrity

• Open Windows Security > Device security
• Select Core isolation
• Set Memory integrity to Off
• Restart the PC

2, Disable the Windows hypervisor

• Open Command Prompt (Admin)
• Run: bcdedit /set hypervisorlaunchtype off
• Restart the PC

3, Verify virtualization status

• Press Win + R, type msinfo32 then press Enter
• Confirm Virtualization-based security shows Not enabled

4, BIOS check (optional)

• Ensure virtualization/IOMMU settings are either fully enabled or fully disabled (avoid mixed states)

If the issue continues, you may consider reaching out to the game publisher’s support team, as they can provide guidance tailored to their anti‑cheat requirements.

Let me know if you need further assistance, feel free to ask me by clicking "Add Comment" or "Add Answer" if you cannot add comment so your response will be visible. Thanks for your effort.

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Answer 2

The most recent Windows updates can change how security and virtualization features interact with kernel-mode drivers and IOMMU-based protections, which can affect anti-cheat systems like Vanguard and FACEIT.

Relevant points from the provided information:

1. IOMMU and GPU/driver behavior
   • Windows uses IOMMU-based GPU isolation and an IoMmu model to restrict device DMA and to share virtual address spaces between CPU and GPU.
   • When IOMMU-based isolation is enabled, the OS restricts device access to system memory through logical addresses and IOMMU translation. If a driver or device attempts DMA outside allowed ranges, it is blocked.
   • Drivers must explicitly support the IoMmu model (for example, by setting DXGK_VIDMMCAPS::IoMmuSupported) to work correctly with these protections.
   • If a driver or anti-cheat component relies on low-level access that conflicts with IOMMU or Kernel DMA protections, updates that tighten these protections can cause failures or unexpected behavior.
   References:
   • IOMMU-based GPU isolation is enabled by default in some security scenarios (for example, when Windows Defender Application Guard/container virtualization is in use) and can also be tied to secure virtual machines.
   • Once IOMMU is enabled in such scenarios, it cannot be disabled without changing the underlying security configuration.
2. Kernel DMA Protection and legacy devices
   • When Kernel DMA Protection is enabled, legacy PCI devices that attempt unsupported DMA can trigger DRIVER_VERIFIER_DMA_VIOLATION with an IOMMU-detected DMA violation.
   • This is a known behavior when older hardware or drivers are not fully compatible with the newer DMA/IOMMU protections.
3. Driver and application compatibility with memory integrity / VBS
   • Memory integrity (HVCI) and virtualization-based security (VBS) have been requirements for driver compatibility since Windows 10 Anniversary Update, but some drivers and applications (including anti-cheat solutions) can still be incompatible.
   • Incompatibilities can cause malfunctioning software, device failures, or even boot issues when these protections are enabled or tightened by an update.
   • Anti-cheat solutions are explicitly listed as a category where incompatibilities with memory integrity have been observed.

Given these points, the likely pattern is:

• A recent Windows update tightened or changed behavior around IOMMU, Kernel DMA Protection, or memory integrity/VBS.
• Vanguard and/or FACEIT anti-cheat drivers may be using techniques that are now blocked or more strictly validated by these protections, leading to failed detection or initialization.

Actionable steps based on the provided material:

1. Check for updated anti-cheat/game components
   • Ensure VALORANT and FACEIT are fully updated so that the latest anti-cheat drivers (which may include fixes for newer Windows builds and IOMMU/VBS behavior) are installed.
   • Many anti-cheat vendors release patches specifically to restore compatibility after Windows security changes.
2. Check for updated system drivers
   • Install all available Windows Updates again after the problematic update, as additional fixes may have been released.
   • Update GPU and chipset drivers from the hardware vendor, as these must correctly support the IoMmu model and newer DMA protections.
3. Review security features that affect IOMMU and DMA
   • If Kernel DMA Protection is enabled and there are legacy PCI or non–fully compliant devices, this can cause IOMMU-related DMA violations. In environments where such legacy hardware is present, disabling Kernel DMA Protection in firmware/BIOS is the documented workaround for the specific DRIVER_VERIFIER_DMA_VIOLATION scenario.
   • If memory integrity/VBS is enabled, and an anti-cheat driver is not compliant, this can cause failures. The recommended approach is to look for updated, compatible drivers first; only if none exist and the software is critical would disabling memory integrity be considered, understanding the security trade-offs.
4. If the issue persists
   • If updated anti-cheat components and drivers do not resolve the problem, and the issue started immediately after a specific Windows update, the remaining options are:
     • Monitor for a subsequent Windows update or vendor patch that addresses the incompatibility.
     • Temporarily avoid the affected game/anti-cheat on that machine until compatibility is restored.

Because the provided material does not include VALORANT- or FACEIT-specific configuration steps, the core guidance is to focus on:

• Keeping anti-cheat and drivers updated to versions compatible with IOMMU, Kernel DMA Protection, and memory integrity.
• Adjusting security features only as a last resort and with awareness of the security impact.

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References:

• IOMMU-based GPU isolation
• IoMmu model
• Stop code DRIVER_VERIFIER_DMA_VIOLATION when Kernel DMA Protection is enabled
• Driver compatibility with memory integrity and VBS