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====== Enabling Nested Virtualization for Windows VMs in Proxmox ======

===== 1. Enable Nested Virtualization on Host =====

Check current nested virtualization status: <code bash>

For Intel CPUs

cat /sys/module/kvm_intel/parameters/nested

For AMD CPUs

cat /sys/module/kvm_amd/parameters/nested </code>

Enable nested virtualization persistently:

<code bash>
# For Intel CPUs
echo "options kvm-intel nested=Y" > /etc/modprobe.d/kvm-intel.conf
modprobe -r kvm_intel
modprobe kvm_intelFor AMD CPUs

echo "options kvm-amd nested=1" > /etc/modprobe.d/kvm-amd.conf modprobe -r kvm_amd modprobe kvm_amd </code>

Note: Reboot the host or reload kernel modules for changes to take effect.

===== 2. Configure Windows VM =====

Set CPU type to ''host'': <code bash> qm set <VMID> --cpu host </code>

For AMD CPUs, add to VM configuration (''/etc/pve/qemu-server/<VMID>.conf''): <code> args: -cpu host,+svm </code>

===== 3. Verify Nested Virtualization =====

Inside Windows VM, use these methods to verify:

· Install WSL or Cygwin and run: <code bash> egrep --color -i "svm|vmx" /proc/cpuinfo </code>
· Use Windows ''coreinfo'' utility
· Check Windows Features for Hyper-V installation capability

===== 4. Troubleshooting =====

Blue Screen Errors: <code bash> echo "options kvm ignore_msrs=1" >> /etc/modprobe.d/kvm.conf modprobe -r kvm modprobe kvm </code>

Hyper-V Enlightenments (if needed): Add to VM configuration: <code> args: -cpu host,-hv_ipi,-hv_relaxed,-hv_reset,-hv_runtime,-hv_spinlocks,-hv_stimer,-hv_synic,-hv_time,-hv_vapic,-hv_vpindex </code>

===== 5. Limitations =====

· No live migration support for VMs with nested virtualization
· Significant performance overhead
· Not recommended for production environments
· Security considerations for nested VM isolation

===== 6. Proxmox Version Compatibility =====

· Ensure Proxmox is updated to latest version
· Kernel version ''proxmox-kernel-6.2.16-19'' or newer recommended
· Check for updates with: <code bash> apt update && apt upgrade </code>

Note: Replace ''<VMID>'' with your actual virtual machine ID in all commands.