[jamieiles]

If you do that, then on almost every context switch the new process will resume with a cold cache. In the worst case, if you were to send lots of IPC requests to a privileged process then your process could have a cold cache far too often.

Many older generations of ARM (v5 and earlier) used a virtually indexed, virtually tagged (VIVT) cache to reduce latency but this required an L1 flush on every context switch and that was incredibly painful!