My understanding is that with course grain SVM, they allocate a buffer on the GPU and a buffer on the CPU at the same virtual address. i.e. so the GPU and CPU see it at them at same addresses and all the pointers within it point at the correct spot.
When you do a sync it copies the relevant buffer across.
With zero copy the GPU reads directly from the CPU's memory. It maybe that course grain SVM uses a zero copy buffer by then it may not.
It may depend on whether the GPU is discrete or not. i.e. with an APU use a zero copy buffer, with a dGpu use separate buffers and copy them back and forth.
(me, I want to see a dGPU connected via Hyper Transport... or a really big APU in a multi socked motherboard.)