I do believe that majority of mining farm is located in China but I doubt that majority of it is owned by chinese. The reason for this is that if ever the majority of hashes is owned by Chinese then the increase in blocksize will never had problem in getting the percentage it wanted for hardforking bitcoin. But it seems it isn't controlled by chinese.
Yes, the majority of mining farms are located in china due to low electricity cost and other factors and they can be hold by the foreigners. But i still think China has control over them and they are not allowed to operate like a free zone in Dubai etc. For the past one and a half year, china has really emerged as a bitcoin greatest market with highest number of bitcoin farms.