+ * Return the pointer to the largepage write count for a given
+ * gfn, handling slots that are not large page aligned.
+ */
+static int *slot_largepage_idx(gfn_t gfn, struct kvm_memory_slot *slot)
+{
+ unsigned long idx;
+
+ idx = (gfn / KVM_PAGES_PER_HPAGE) -
+ (slot->base_gfn / KVM_PAGES_PER_HPAGE);
+ return &slot->lpage_info[idx].write_count;
+}
+
+static void account_shadowed(struct kvm *kvm, gfn_t gfn)
+{
+ int *write_count;
+
+ write_count = slot_largepage_idx(gfn, gfn_to_memslot(kvm, gfn));
+ *write_count += 1;
+ WARN_ON(*write_count > KVM_PAGES_PER_HPAGE);
+}
+
+static void unaccount_shadowed(struct kvm *kvm, gfn_t gfn)
+{
+ int *write_count;
+
+ write_count = slot_largepage_idx(gfn, gfn_to_memslot(kvm, gfn));
+ *write_count -= 1;
+ WARN_ON(*write_count < 0);
+}
+
+static int has_wrprotected_page(struct kvm *kvm, gfn_t gfn)
+{
+ struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn);
+ int *largepage_idx;
+
+ if (slot) {
+ largepage_idx = slot_largepage_idx(gfn, slot);
+ return *largepage_idx;
+ }
+
+ return 1;
+}
+
+static int host_largepage_backed(struct kvm *kvm, gfn_t gfn)
+{
+ struct vm_area_struct *vma;
+ unsigned long addr;
+
+ addr = gfn_to_hva(kvm, gfn);
+ if (kvm_is_error_hva(addr))
+ return 0;
+
+ vma = find_vma(current->mm, addr);
+ if (vma && is_vm_hugetlb_page(vma))
+ return 1;
+
+ return 0;
+}
+
+static int is_largepage_backed(struct kvm_vcpu *vcpu, gfn_t large_gfn)
+{
+ struct kvm_memory_slot *slot;
+
+ if (has_wrprotected_page(vcpu->kvm, large_gfn))
+ return 0;
+
+ if (!host_largepage_backed(vcpu->kvm, large_gfn))
+ return 0;
+
+ slot = gfn_to_memslot(vcpu->kvm, large_gfn);
+ if (slot && slot->dirty_bitmap)
+ return 0;
+
+ return 1;
+}
+
+/*