I know this order of tenses could exist in English, but it looks so odd standing alone. The only context I could see for this would be something like "I know what you had done. Now, tell me what you did at that time."
Even that sounds a bit awkward to me. "I knew what you had done" would be a better English sentence grammatically for this exercise.
Honestly, if I just saw this sentence standing alone, I would simply translate it "I know what you did." Greek clearly uses a perfect where we would use a simple past.
In this sentence, κάνει is the απαρέμφατο form -- perhaps "past participle" is closest as that's the form used in English for form the present perfect and past perfect tenses (but there's a separate passive past participle form in Greek).
The απαρέμφατο is invariable like e.g. "done" in English, and the είχες shows the person and number.
The απαρέμφατο looks like the third person singular of the aorist subjunctive (e.g. the form used after αυτός θα ....).