Comment 1 for bug 1830864

This happens because:
 * the host kernel is older than 4.15 and does not expose ID registers to userspace via the KVM_GET_ONE_REG ioctl
 * our fallback set of ID register values in target/arm/kvm64.c kvm_arm_get_host_cpu_features() is extremely minimalist
 * the consistency checks on ID register values in arm_cpu_realizefn() are made unconditionally, rather than only if we're using TCG

https://patchwork.ozlabs.org/patch/1133724/ is a fix for this which takes the approach of only asserting if we're using TCG, since that's really the case we're guarding for problems with and the only one that's a bug in QEMU (as opposed to an issue with the host kernel or host CPU).