KVM: introduce KVM_ERR_PTR_BAD_PAGE

It is used to eliminate the overload of function call and cleanup
the code
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

include/linux/kvm_host.h

@@ -68,6 +68,13 @@ static inline int is_invalid_pfn(pfn_t pfn)
 	return !is_noslot_pfn(pfn) && is_error_pfn(pfn);
 }
 
+#define KVM_ERR_PTR_BAD_PAGE	(ERR_PTR(-ENOENT))
+
+static inline int is_error_page(struct page *page)
+{
+	return IS_ERR(page);
+}
+
 /*
  * vcpu->requests bit members
  */
@@ -409,7 +416,6 @@ id_to_memslot(struct kvm_memslots *slots, int id)
 	return slot;
 }
 
-int is_error_page(struct page *page);
 int kvm_is_error_hva(unsigned long addr);
 int kvm_set_memory_region(struct kvm *kvm,
 			  struct kvm_userspace_memory_region *mem,
@@ -436,7 +442,6 @@ void kvm_arch_flush_shadow(struct kvm *kvm);
 int gfn_to_page_many_atomic(struct kvm *kvm, gfn_t gfn, struct page **pages,
 			    int nr_pages);
 
-struct page *get_bad_page(void);
 struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn);
 unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn);
 void kvm_release_page_clean(struct page *page);

virt/kvm/async_pf.c

@@ -203,7 +203,7 @@ int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu)
 	if (!work)
 		return -ENOMEM;
 
-	work->page = get_bad_page();
+	work->page = KVM_ERR_PTR_BAD_PAGE;
 	INIT_LIST_HEAD(&work->queue); /* for list_del to work */
 
 	spin_lock(&vcpu->async_pf.lock);

virt/kvm/kvm_main.c

@@ -922,17 +922,6 @@ void kvm_disable_largepages(void)
 }
 EXPORT_SYMBOL_GPL(kvm_disable_largepages);
 
-int is_error_page(struct page *page)
-{
-	return IS_ERR(page);
-}
-EXPORT_SYMBOL_GPL(is_error_page);
-
-struct page *get_bad_page(void)
-{
-	return ERR_PTR(-ENOENT);
-}
-
 static inline unsigned long bad_hva(void)
 {
 	return PAGE_OFFSET;
@@ -1179,7 +1168,7 @@ static struct page *kvm_pfn_to_page(pfn_t pfn)
 	WARN_ON(kvm_is_mmio_pfn(pfn));
 
 	if (is_error_pfn(pfn) || kvm_is_mmio_pfn(pfn))
-		return get_bad_page();
+		return KVM_ERR_PTR_BAD_PAGE;
 
 	return pfn_to_page(pfn);
 }