Considering the fact that both Ubuntu and Elementary require SSE to boot, I'd wait to get decoding fixed. I wrote a test kernel module that reliably reproduces your issue on qemu edu device. Whenever QEMU prints Unimplemented handler Instruction pointer only moves two bytes further, instead of the instruction length. That corrupts code execution as the next instruction after unimplemented handler is decoded from the wrong address.
Considering the fact that both Ubuntu and Elementary require SSE to boot, I'd wait to get decoding fixed. I wrote a test kernel module that reliably reproduces your issue on qemu edu device. Whenever QEMU prints Unimplemented handler Instruction pointer only moves two bytes further, instead of the instruction length. That corrupts code execution as the next instruction after unimplemented handler is decoded from the wrong address.