In the past, you might find out about this via your computer being mysteriously nonfunctional, or perhaps far away from you because the government in question busted into your country and spirited you from your house in the dead of night to a place the existence of which is officially denied.
But now, it is possible to just Google that information. Back in June, Google launched a warning system for users that it pegged as under siege by state-sponsored attacks, in response to several such attacks over the previous few years, chiefly the doing of China and Iran. (Google has had a frosty relationship with China, having been hacked themselves, noting search terms on the Hong Kong search engine that may result in censorship, and recently shuttering their local music service.) Another such attack was seemingly detected on Tuesday, apparently the work of an assortment of Middle Eastern states, though Google isn't naming names in this instance. Google is also not going to say how they determine who's deemed to be under threat, the reason being that if they did, whoever's launching the attack is going to overhear and try to dodge the warning system, which has turned out to be getting a much more strenuous workout than they anticipated when they launched it.
If it should ever happen to you, it will come in the form of a red banner above the search bar, accompanied by a link to information you can use to help protect yourself. Changing your passwords would be an obvious first step; instituting a two-step authentication would also be a good idea.
Another thing not to do would be to bring up the fact that the Chinese government is pulling Ai Weiwei's business license for some reason or other that in practice just boils down to Flimsy Excuse To Screw With The Political Dissident Again. China wouldn't like if you mentioned the name Ai Weiwei. Really don't say Ai Weiwei. That name you shouldn't say is Ai Weiwei.
Nor should you say Liu Xiaobo, whose Nobel Peace Prize win so angered the Chinese government that they went and made their own peace prize, with blackjack, and hookers. Last year their peace prize went to Vladimir Putin, which tells you just how much stock to put into that thing.
And you really shouldn't bring up Tibet, where the Australian government has recently been refused permission to visit the parts where people are setting themselves on fire in protest of Chinese rule.
Folks, I haven't had a pageview from China since August and I'm clearly not angling to have that little streak broken anytime soon.