How to change page permission from inside the kernel?

[Ahmed Soliman]

I have a memory page allocated with mmap() from user space, This
address is passed to some kernel module (kvm_intel to be specific) and
i want to know how can I change the page permission from inside there
My goal is to achieve something like this
              mprotect(mem, PAGE_SIZE, PROT_READ)
except for mprotect can't be called from the kernel, and I couldn't
find the right way to do it.