Firecracker ARM CPU templates failed on newer host kernels
Brief
Enabling the permission does not change what the guest already sees.
Notes
213849e5d969. Enables KVM_CAP_ARM_WRITABLE_IMP_ID_REGS on aarch64 so custom templates can write MIDR/REVIDR/AIDR. Snapshot restore of unchanged values already worked. Direct ioctl; kvm-ioctls has no aarch64 enable_cap yet.
Commit 213849e5d969d88f00de63c907577301601e099f