Just positive feedback loop. The term "positive" or "negative" refers to the effects of the feedback path on the overall system, a negative feedback loop attempts to negate any changes in the outputs, while a positive feedback amplifies any changes.

Perhaps "Vicious Cycle" and "Virtuous Cycle" is better terminology in this case. Both of them describe self-reinforcing (i.e. positive) feedback loops, while also making clear judgement on the desirability of the consequences.

Just feedback loop*

Adding positive/negative on it is unnecessary specificity