My kernel line is (I disable the spectr/meltdown mitigations so ignore those parts):
root=/dev/mapper/ssd-arch--root rw intel_iommu=on iommu=pt i915.enable_guc=3 i915.disable_power_well=0 i915.enable_psr=1 i915.enable_fbc=1 i915.enable_rc6=1 pci=nomsi,noaer pti=off spectre_v2=off l1tf=off nospec_store_bypass_disable no_stf_barrier
I don't think has any significant modifications. Eventually I want to switch over to using the newer q35 architecture. The only issues I've had with the VM are some audio glitches in some games and it has recently had issues with hugepages so I've had to disable that.