Holding key down using input-linux freezes guest

Qemu release version 2.8.0
KVM, kernel 4.9.1

When using the -object input-linux capability in qemu for passthrough of input/evdev devices, I found that when a key is held for a few seconds or more (such as ctrl key), the guest system freezes until the key is released. In some cases, mouse control is also lost following one of these "freezes". I also noticed that one of the four cpu cores I have the guest pinned to ramps to 100% during these freezes.