From fe19c91c6b0293441aca084e88a60ee59640922c Mon Sep 17 00:00:00 2001
From: Sander <hey@sandydoo.me>
Date: Wed, 22 Nov 2023 14:53:08 +0000
Subject: [PATCH] feat: enable KVM on Linux if available

---
 README.md      |  2 ++
 action.yml     |  5 +++++
 install-nix.sh | 11 +++++++++++
 3 files changed, 18 insertions(+)

diff --git a/README.md b/README.md
index c446da36..ae1bbee4 100644
--- a/README.md
+++ b/README.md
@@ -73,6 +73,8 @@ To install Nix from any commit, go to [the corresponding installer_test action](
 
 - `nix_path`: set `NIX_PATH` environment variable, for example `nixpkgs=channel:nixos-unstable`
 
+- `enable_kvm`: whether to enable KVM for hardware-accelerated virtualization on Linux. Enabled by default if available.
+
 ---
 
 ## FAQ
diff --git a/action.yml b/action.yml
index 9bd8e053..d33114a0 100644
--- a/action.yml
+++ b/action.yml
@@ -12,6 +12,10 @@ inputs:
     description: 'Additional installer flags passed to the installer script.'
   nix_path:
     description: 'Set NIX_PATH environment variable.'
+  enable_kvm:
+    description: 'Enable KVM for hardware-accelerated virtualization on Linux, if available.'
+    required: false
+    default: true
 branding:
   color: 'blue'
   icon: 'sun'
@@ -26,4 +30,5 @@ runs:
         INPUT_INSTALL_OPTIONS: ${{ inputs.install_options }}
         INPUT_INSTALL_URL: ${{ inputs.install_url }}
         INPUT_NIX_PATH: ${{ inputs.nix_path }}
+        INPUT_ENABLE_KVM: ${{ inputs.enable_kvm }}
         GITHUB_TOKEN: ${{ github.token }}
diff --git a/install-nix.sh b/install-nix.sh
index 4462f3a7..c5265a49 100755
--- a/install-nix.sh
+++ b/install-nix.sh
@@ -6,6 +6,17 @@ if nix_path="$(type -p nix)" ; then
   exit
 fi
 
+if [[ ($OSTYPE =~ linux) && ($INPUT_ENABLE_KVM == 'true') ]]; then
+  enable_kvm() {
+    echo 'KERNEL=="kvm", GROUP="kvm", MODE="0666", OPTIONS+="static_node=kvm"' | sudo tee /etc/udev/rules.d/99-install-nix-action-kvm.rules
+    sudo udevadm control --reload-rules && sudo udevadm trigger --name-match=kvm
+  }
+
+  echo '::group::Enabling KVM support'
+  enable_kvm && echo 'Enabled KVM' || echo 'KVM is not available'
+  echo '::endgroup::'
+fi
+
 # GitHub command to put the following log messages into a group which is collapsed by default
 echo "::group::Installing Nix"