I encountered the same error, and after researching the need to use freezer, I found out that it is not needed when using cgroup2. If systemd.unified_cgroup_hierarchy=0 is added in the GRUB’s command line, it is forcing your system to use cgroups1 which is being deprecated.
I noticed that when I tried to run podman, and I got a warning advising that I was using cgroup1. Once I removed the line, the message disappeared.
As I understand, the FAIL message from virt-host-validate is irrelevant for a system using cgroup2, because cgroup_freezer should be disabled. Info here
The other parameters enhance the performance for an hypervisor. Enabling I/O Memory Management Unit (IOMMU) will allow devices with SR-IO capabilities to expose Virtual Functions (VF’s) to the VM, and they also will expose Host devices directly to the VM.
They are usually identified as passtrough devices (i.e CPUs).
Intel CPU’s (VT-d and VT-x) will need iommu=pt intel_iommu=on
AMD CPU’s (VT-Vi) will need iommu=pt
In case of AMD, the IOMMU is enabled by default. PT=passthrough
Great documentation HERE