Block China on GCP/VM firewall

There are several ways to achieve your use case. With GCP product, you can use Cloud Armor for a location-based traffic filtering through its Web Application Firewall.

Here are several threads that can also help you on your use case:

1. https://stackoverflow.com/questions/23682114/google-app-engine-block-incoming-traffic-by-country
2. Relatively easy way to block all traffic from a specific country?
3. https://stackoverflow.com/questions/29704635/allow-only-specific-countries-to-connect-to-vm
4. https://stackoverflow.com/questions/26168240/google-cloud-block-incoming-connections
5. https://stackoverflow.com/questions/35000410/block-offending-ip-from-google-compute-instance