Is there a difference between user space and the kernel in physical memory on Linux x86-64?

Question

That is, given the physical address, can I determine if this address is from user space or not?

As far as I know, in the virtual address space, the kernel will use the upper half and user space will use the lower half. But what about the physical address space?

What complicates the problem is that I want to check the guest physical address in KVM, which means that I cannot call some kernel functions in the guest OS. So I want to know if there is an explicit dividing line?

Answer 1

Not.

Almost any physical frame of a page can be mapped to a virtual user space address or to a virtual kernel address, or even both at the same time.