KVM: MMU: introduce slot_handle_level_range() and its helpers

There are several places walking all rmaps for the memslot so that
introduce common functions to cleanup the code

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu.c

@@ -4454,6 +4454,75 @@ void kvm_mmu_setup(struct kvm_vcpu *vcpu)
 	init_kvm_mmu(vcpu);
 }
 
+/* The return value indicates if tlb flush on all vcpus is needed. */
+typedef bool (*slot_level_handler) (struct kvm *kvm, unsigned long *rmap);
+
+/* The caller should hold mmu-lock before calling this function. */
+static bool
+slot_handle_level_range(struct kvm *kvm, struct kvm_memory_slot *memslot,
+			slot_level_handler fn, int start_level, int end_level,
+			gfn_t start_gfn, gfn_t end_gfn, bool lock_flush_tlb)
+{
+	struct slot_rmap_walk_iterator iterator;
+	bool flush = false;
+
+	for_each_slot_rmap_range(memslot, start_level, end_level, start_gfn,
+			end_gfn, &iterator) {
+		if (iterator.rmap)
+			flush |= fn(kvm, iterator.rmap);
+
+		if (need_resched() || spin_needbreak(&kvm->mmu_lock)) {
+			if (flush && lock_flush_tlb) {
+				kvm_flush_remote_tlbs(kvm);
+				flush = false;
+			}
+			cond_resched_lock(&kvm->mmu_lock);
+		}
+	}
+
+	if (flush && lock_flush_tlb) {
+		kvm_flush_remote_tlbs(kvm);
+		flush = false;
+	}
+
+	return flush;
+}
+
+static bool
+slot_handle_level(struct kvm *kvm, struct kvm_memory_slot *memslot,
+		  slot_level_handler fn, int start_level, int end_level,
+		  bool lock_flush_tlb)
+{
+	return slot_handle_level_range(kvm, memslot, fn, start_level,
+			end_level, memslot->base_gfn,
+			memslot->base_gfn + memslot->npages - 1,
+			lock_flush_tlb);
+}
+
+static bool
+slot_handle_all_level(struct kvm *kvm, struct kvm_memory_slot *memslot,
+		      slot_level_handler fn, bool lock_flush_tlb)
+{
+	return slot_handle_level(kvm, memslot, fn, PT_PAGE_TABLE_LEVEL,
+				 PT_MAX_HUGEPAGE_LEVEL, lock_flush_tlb);
+}
+
+static bool
+slot_handle_large_level(struct kvm *kvm, struct kvm_memory_slot *memslot,
+			slot_level_handler fn, bool lock_flush_tlb)
+{
+	return slot_handle_level(kvm, memslot, fn, PT_PAGE_TABLE_LEVEL + 1,
+				 PT_MAX_HUGEPAGE_LEVEL, lock_flush_tlb);
+}
+
+static bool
+slot_handle_leaf(struct kvm *kvm, struct kvm_memory_slot *memslot,
+		 slot_level_handler fn, bool lock_flush_tlb)
+{
+	return slot_handle_level(kvm, memslot, fn, PT_PAGE_TABLE_LEVEL,
+				 PT_PAGE_TABLE_LEVEL, lock_flush_tlb);
+}
+
 void kvm_mmu_slot_remove_write_access(struct kvm *kvm,
 				      struct kvm_memory_slot *memslot)
 {