+typedef void (*pte_list_walk_fn) (u64 *spte);
+static void pte_list_walk(unsigned long *pte_list, pte_list_walk_fn fn)
+{
+ struct pte_list_desc *desc;
+ int i;
+
+ if (!*pte_list)
+ return;
+
+ if (!(*pte_list & 1))
+ return fn((u64 *)*pte_list);
+
+ desc = (struct pte_list_desc *)(*pte_list & ~1ul);
+ while (desc) {
+ for (i = 0; i < PTE_LIST_EXT && desc->sptes[i]; ++i)
+ fn(desc->sptes[i]);
+ desc = desc->more;
+ }
+}
+
+/*
+ * Take gfn and return the reverse mapping to it.
+ */
+static unsigned long *gfn_to_rmap(struct kvm *kvm, gfn_t gfn, int level)
+{
+ struct kvm_memory_slot *slot;
+ struct kvm_lpage_info *linfo;
+
+ slot = gfn_to_memslot(kvm, gfn);
+ if (likely(level == PT_PAGE_TABLE_LEVEL))
+ return &slot->rmap[gfn - slot->base_gfn];
+
+ linfo = lpage_info_slot(gfn, slot, level);
+
+ return &linfo->rmap_pde;
+}
+
+static int rmap_add(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn)
+{
+ struct kvm_mmu_page *sp;
+ unsigned long *rmapp;
+
+ sp = page_header(__pa(spte));
+ kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn);
+ rmapp = gfn_to_rmap(vcpu->kvm, gfn, sp->role.level);
+ return pte_list_add(vcpu, spte, rmapp);
+}
+
+static u64 *rmap_next(struct kvm *kvm, unsigned long *rmapp, u64 *spte)
+{
+ return pte_list_next(rmapp, spte);
+}
+
+static void rmap_remove(struct kvm *kvm, u64 *spte)
+{
+ struct kvm_mmu_page *sp;
+ gfn_t gfn;
+ unsigned long *rmapp;
+
+ sp = page_header(__pa(spte));
+ gfn = kvm_mmu_page_get_gfn(sp, spte - sp->spt);
+ rmapp = gfn_to_rmap(kvm, gfn, sp->role.level);
+ pte_list_remove(spte, rmapp);
+}
+