PT_PGD
(*func)(mm, virt_to_page(pgd), PT_PGD);
level == PT_PGD ? UVMF_TLB_FLUSH : 0);
xen_pin_page(mm, virt_to_page(user_pgd), PT_PGD);
level == PT_PGD ? UVMF_TLB_FLUSH : 0);
xen_unpin_page(mm, virt_to_page(user_pgd), PT_PGD);