KVM: introduce update_memslots function

Introduce update_memslots to update slot which will be update to
kvm->memslots
Signed-off-by: NXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

arch/x86/kvm/x86.c

@@ -3546,7 +3546,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
 		memslot = &slots->memslots[log->slot];
 		memslot->dirty_bitmap = dirty_bitmap;
 		memslot->nr_dirty_pages = 0;
-		slots->generation++;
+		update_memslots(slots, NULL);
 
 		old_slots = kvm->memslots;
 		rcu_assign_pointer(kvm->memslots, slots);

include/linux/kvm_host.h

@@ -320,6 +320,7 @@ void kvm_exit(void);
 
 void kvm_get_kvm(struct kvm *kvm);
 void kvm_put_kvm(struct kvm *kvm);
+void update_memslots(struct kvm_memslots *slots, struct kvm_memory_slot *new);
 
 static inline struct kvm_memslots *kvm_memslots(struct kvm *kvm)
 {

virt/kvm/kvm_main.c

@@ -630,6 +630,19 @@ static int kvm_create_dirty_bitmap(struct kvm_memory_slot *memslot)
 }
 #endif /* !CONFIG_S390 */
 
+void update_memslots(struct kvm_memslots *slots, struct kvm_memory_slot *new)
+{
+	if (new) {
+		int id = new->id;
+
+		slots->memslots[id] = *new;
+		if (id >= slots->nmemslots)
+			slots->nmemslots = id + 1;
+	}
+
+	slots->generation++;
+}
+
 /*
  * Allocate some memory and give it an address in the guest physical address
  * space.
@@ -780,10 +793,8 @@ int __kvm_set_memory_region(struct kvm *kvm,
 				GFP_KERNEL);
 		if (!slots)
 			goto out_free;
-		if (mem->slot >= slots->nmemslots)
-			slots->nmemslots = mem->slot + 1;
-		slots->generation++;
 		slots->memslots[mem->slot].flags |= KVM_MEMSLOT_INVALID;
+		update_memslots(slots, NULL);
 
 		old_memslots = kvm->memslots;
 		rcu_assign_pointer(kvm->memslots, slots);
@@ -815,9 +826,6 @@ int __kvm_set_memory_region(struct kvm *kvm,
 			GFP_KERNEL);
 	if (!slots)
 		goto out_free;
-	if (mem->slot >= slots->nmemslots)
-		slots->nmemslots = mem->slot + 1;
-	slots->generation++;
 
 	/* actual memory is freed via old in kvm_free_physmem_slot below */
 	if (!npages) {
@@ -827,7 +835,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 			new.lpage_info[i] = NULL;
 	}
 
-	slots->memslots[mem->slot] = new;
+	update_memslots(slots, &new);
 	old_memslots = kvm->memslots;
 	rcu_assign_pointer(kvm->memslots, slots);
 	synchronize_srcu_expedited(&kvm->srcu);