This patch adds arm64 helpers to write protect pmds/ptes and retrieve
permissions while logging dirty pages. Also adds prototype to write protect
a memory slot and adds a pmd define to check for read-only pmds.
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NMario Smarduch <m.smarduch@samsung.com>