Do I need to extend visa?

Hello, I've got my Chinese visa and saw that will expire 7 days from the day I will arrive in China. I have applied for 30 days of duration of stay for tourist visa but I did mada a mistake of understanding that topic of validity of visa which I choosed 1 month, I should've choosed 2 months. Can I stay those 30 days or 7 days or I need to extend visa in China?