Windows 11 SR-IOV Passthrough (Headless) on CachyOS

fusion_on_linux.md

Windows 11 SR-IOV Passthrough (Headless) on CachyOS

1. Prerequisites & Hardware

• OS: CachyOS (Arch-based)
• CPU: Intel 12th/13th/14th Gen (e.g., i5-13600K) with UHD 770
• GPU Strategy: SR-IOV (Single Root I/O Virtualization) to create virtual GPU slices.
• BIOS Settings:
  • VT-d: Enabled
  • Above 4G Decoding: Enabled
  • Re-Size BAR: DISABLED (Crucial for 13th Gen iGPU passthrough stability)
  • DVMT Pre-Allocated: 64MB (Recommended)

2. Host Setup (CachyOS)

Install Packages

Install QEMU, KVM, and headers required for the SR-IOV driver.

sudo pacman -Syu qemu-full virt-manager virt-viewer dnsmasq vde2 bridge-utils openbsd-netcat libguestfs swtpm linux-cachyos-headers ethtool

Install SR-IOV Driver (AUR)

We use the custom driver to unlock 7 Virtual Functions on the consumer iGPU.

Bash

paru -S i915-sriov-dkms
# OR
yay -S i915-sriov-dkms

Configure Bootloader (Limine)

Enable IOMMU and create the virtual GPU slices at boot.

1. Edit config: sudo nano /boot/limine.conf

2. Append to cmdline:

   Plaintext

   intel_iommu=on iommu=pt i915.enable_guc=3 i915.max_vfs=7 kvm.ignore_msrs=1 report_ignored_msrs=0
   

3. Reboot Host.

Verification: Run lspci | grep VGA. You should see 00:02.0 (Physical) AND 00:02.1 through 00:02.7 (Virtual Slices).

Fix Networking (Docker Conflict & VirtIO Checksum)

Docker breaks KVM networking, and VirtIO causes DNS failures.

1. Allow KVM Traffic (Fix "No Internet" in VM):

   Bash

   # Allow forwarding
   sudo iptables -P FORWARD ACCEPT
   # Save persistence
   sudo iptables-save | sudo tee /etc/iptables/iptables.rules
   sudo systemctl enable --now iptables
   

2. Fix DNS/Packet Corruption (Checksum Offload):

   Bash

   sudo ethtool -K virbr0 tx off
   

   (Note: This might need a script to run on boot).

3. Virtual Machine Creation (Virt-Manager)

• ISO: Windows 11

• Firmware: UEFI (OVMF)

• TPM: CRB (Emulated via swtpm)

• Network: Virtual Network 'default' : NAT (e1000e or virtio)

• Bypass MS Account: Shift+F10 during setup -> OOBE\BYPASSNRO.

4. XML Configuration (SR-IOV & Headless)

Crucial Settings:

• Use 00:02.1 (Slice 1), NOT 00:02.0 (Physical).

• Remove all legacy hacks (rom bar=on, x-vga=on, opregion).

• Topology: Ensure GPU is NOT on Bus 0 or 1. Let Libvirt auto-assign (e.g., Bus 5-9).

Final Working Device Block:

XML

<hostdev mode="subsystem" type="pci" managed="yes">
  <source>
    <address domain="0x0000" bus="0x00" slot="0x02" function="0x1"/>
  </source>
  <rom bar="off"/>
  </hostdev>

QEMU Args (Spoofing Only):

XML

<qemu:commandline>
  <qemu:arg value="-global"/>
  <qemu:arg value="vfio-pci.x-pci-sub-vendor-id=0x1043"/>
  <qemu:arg value="-global"/>
  <qemu:arg value="vfio-pci.x-pci-sub-device-id=0x8882"/>
</qemu:commandline>

Hyper-V Spoofing (Hide VM status):

Inside -> :

XML

<vendor_id state="on" value="1234567890ab"/>

Inside <features>:

XML

<kvm>
  <hidden state="on"/>
</kvm>

5. Windows Guest Setup

Drivers

1. VirtIO Drivers: Install virtio-win-guest-tools.exe.

2. Intel Graphics: Install standard Intel drivers (Device should show "Intel UHD 770" with NO Code 43).

High Resolution & FPS (Headless Mode)

Since there is no physical monitor, Windows defaults to low res.

1. Download IddSampleDriver (MikeTheTech/Roshkins).

2. Extract to C:\IddSampleDriver.

3. Install Certificate Manually: Right-click IddSampleDriver.cer -> Install -> Local Machine -> Trusted Root Certification Authorities.

4. Run install.bat as Admin.

5. Reboot VM.

6. Display Settings: Select "Display 2" (Idd) -> "Show Only on 2". Set 1080p/1440p and 60/120Hz.

Streaming (Moonlight/Sunshine)

1. VM: Install Sunshine.

   • Config -> Audio/Video -> Encoder: Intel QuickSync.

   • Applications -> Add "Fusion 360" (Path to exe) for seamless launching.

2. Host: Install Moonlight-qt.

   • Settings -> V-Sync: OFF (Fixes "floaty" mouse).

   • Bitrate: 150 Mbps.

   • Connect via IP (e.g., 192.168.122.x).

6. Quality of Life

Shared Folders (VirtioFS)

1. Host: mkdir ~/FusionShare

2. XML:

   XML

   <memoryBacking>
     <source type="memfd"/>
     <access mode="shared"/>
   </memoryBacking>
   <filesystem type="mount" accessmode="passthrough">
     <driver type="virtiofs"/>
     <source dir="/home/user/FusionShare"/>
     <target dir="host_share"/>
   </filesystem>
   

3. Guest: Install WinFSP (Select "Core").

4. Guest: Start service VirtIO-FS Service (Auto).

5. Result: Drive Z: appears in Windows.

• Fusion 360 Performance: Windows Settings -> System -> Display -> Graphics -> Fusion 360 -> High Performance (Intel UHD 770).