Which CL device for GL context?

I hope this isn’t a stupid question, but I’m a bit confused as to how to get “the” OpenCL device associated with a specific GL context. clGetGLContextInfoKHR() returns a list of devices assocated with a GL context/display, and I’m not sure which one it is.

While there are multiple GPUs in my system (2), only one GPU is driving this screen and associated with this GL context. How do I tell which one it is?

The last thing I want to do is have my CL command queue on one GPU and my GL context on the other, since I’m using CL to process GL-generated data.