It's not so much black against white as it is Mugabe against everyone who doesn't worship him. He is getting more and more insane and more and more desperate to stay in power (reminds me of another dictator with a silly mustache, some 60 years ago). Comrade Mugabe (that is what he calls himself) and his goons have been murdering black Zimbabweans for 20 years, including wholesale massacres. This is not just a political thing, there is also an ethnic aspect to it. Most of the victims have been Ndebele, while Mugabe is Shona, the largest ethnic group in the country.
There are probably two reasons why the white part of the population were left (relatively) alone as long as they were. First, they were running the economy, without their business there would not be anything for Mugabe to steal. Second, murdering white farmers leads to bad publicity in the international media, which again leads to less aid money from abroad, aid money that these two bit dictators consider their personal income.
Too bad, it should have been a great country. It is a great country, the people I met were nice, they just need to do some serious weeding in the political landscape. I'd like to go back there some day...
BTW, I've been just yards away from the comrade himself. I was in a taxi in Harare when we were "overtaken" by the biggest freakin' motorcade I have ever seen (but then I come from a place where cabinet ministers are known to go to work by subway and bicycle
). The great leader was traveling with several dozen police cars and motorcycles and multiple truckloads of infantry(!) and according to the taxi driver this was if anything "low key". It must be great to feel so loved by the people that you need that kind of protection.