From a2465483e89026df3ea939f95f8cf8de6717ea9c Mon Sep 17 00:00:00 2001
From: Max Hausch <max.hausch@helsinki-systems.de>
Date: Tue, 5 Apr 2022 11:49:42 +0200
Subject: [PATCH] nixos/lib/qemu-common: Opportunistically use KVM

This will try to use KVM if available and fallback to using TCG if not.
Useful for nested virtualisation of arm on x86.
---
 nixos/lib/qemu-common.nix | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/nixos/lib/qemu-common.nix b/nixos/lib/qemu-common.nix
index 20bbe9ff5d9..250f714be0a 100644
--- a/nixos/lib/qemu-common.nix
+++ b/nixos/lib/qemu-common.nix
@@ -23,8 +23,8 @@ rec {
 
   qemuBinary = qemuPkg: {
     x86_64-linux = "${qemuPkg}/bin/qemu-kvm -cpu max";
-    armv7l-linux = "${qemuPkg}/bin/qemu-system-arm -enable-kvm -machine virt -cpu host";
-    aarch64-linux = "${qemuPkg}/bin/qemu-system-aarch64 -enable-kvm -machine virt,gic-version=host -cpu host";
+    armv7l-linux = "${qemuPkg}/bin/qemu-system-arm -machine virt,accel=kvm:tcg -cpu max";
+    aarch64-linux = "${qemuPkg}/bin/qemu-system-aarch64 -machine virt,gic-version=max,accel=kvm:tcg -cpu max";
     powerpc64le-linux = "${qemuPkg}/bin/qemu-system-ppc64 -machine powernv";
     powerpc64-linux = "${qemuPkg}/bin/qemu-system-ppc64 -machine powernv";
     x86_64-darwin = "${qemuPkg}/bin/qemu-kvm -cpu max";