xen/page_alloc: introduce init_free_page_fields() helper

Introduce a new helper to initialize fields that have different uses for
free pages.

Signed-off-by: Carlo Nonato <carlo.nonato@minervasys.tech>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/common/page_alloc.c

@@ -925,6 +925,13 @@ static struct page_info *get_free_buddy(unsigned int zone_lo,
     }
 }
 
+/* Initialise fields which have other uses for free pages. */
+static void init_free_page_fields(struct page_info *pg)
+{
+    pg->u.inuse.type_info = PGT_TYPE_INFO_INITIALIZER;
+    page_set_owner(pg, NULL);
+}
+
 /* Allocate 2^@order contiguous pages. */
 static struct page_info *alloc_heap_pages(
     unsigned int zone_lo, unsigned int zone_hi,
@@ -1033,10 +1040,7 @@ static struct page_info *alloc_heap_pages(
             accumulate_tlbflush(&need_tlbflush, &pg[i],
                                 &tlbflush_timestamp);
 
-        /* Initialise fields which have other uses for free pages. */
-        pg[i].u.inuse.type_info = PGT_TYPE_INFO_INITIALIZER;
-        page_set_owner(&pg[i], NULL);
-
+        init_free_page_fields(&pg[i]);
     }
 
     spin_unlock(&heap_lock);
@@ -2799,9 +2803,7 @@ static bool prepare_staticmem_pages(struct page_info *pg, unsigned long nr_mfns,
          * to PGC_state_inuse.
          */
         pg[i].count_info = PGC_static | PGC_state_inuse;
-        /* Initialise fields which have other uses for free pages. */
-        pg[i].u.inuse.type_info = PGT_TYPE_INFO_INITIALIZER;
-        page_set_owner(&pg[i], NULL);
+        init_free_page_fields(&pg[i]);
     }
 
     spin_unlock(&heap_lock);