PGC_static and PGC_extra need to be preserved when assigning a page.
Define a new macro that groups those flags and use it instead of or'ing
every time.

Signed-off-by: Carlo Nonato <carlo.nonato@minervasys.tech>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---
v13:
- no changes
v12:
- fixed wrong patch sent in v11
- added comment on PGC_preserved
v11:
- removed PGC_broken from PGC_preserved
- removed PGC preservation from mark_page_free()
v10:
- fixed commit message
v9:
- add PGC_broken to PGC_preserved
- clear PGC_extra in alloc_domheap_pages() only if MEMF_no_refcount is set
v8:
- fixed PGC_extra ASSERT fail in alloc_domheap_pages() by removing PGC_extra
  before freeing
v7:
- PGC_preserved used also in mark_page_free()
v6:
- preserved_flags renamed to PGC_preserved
- PGC_preserved is used only in assign_pages()
v5:
- new patch
---
 xen/common/page_alloc.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index da505a79f6..6dc8e0d5c9 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -161,6 +161,10 @@
 #endif
 
 #define PGC_no_buddy_merge PGC_static
+/*
+ * Flags that are preserved in assign_pages() (and only there)
+ */
+#define PGC_preserved (PGC_extra | PGC_static)
 
 #ifndef PGT_TYPE_INFO_INITIALIZER
 #define PGT_TYPE_INFO_INITIALIZER 0
@@ -2385,7 +2389,7 @@ int assign_pages(
 
         for ( i = 0; i < nr; i++ )
         {
-            ASSERT(!(pg[i].count_info & ~(PGC_extra | PGC_static)));
+            ASSERT(!(pg[i].count_info & ~PGC_preserved));
             if ( pg[i].count_info & PGC_extra )
                 extra_pages++;
         }
@@ -2445,7 +2449,7 @@ int assign_pages(
         page_set_owner(&pg[i], d);
         smp_wmb(); /* Domain pointer must be visible before updating refcnt. */
         pg[i].count_info =
-            (pg[i].count_info & (PGC_extra | PGC_static)) | PGC_allocated | 1;
+            (pg[i].count_info & PGC_preserved) | PGC_allocated | 1;
 
         page_list_add_tail(&pg[i], page_to_list(d, &pg[i]));
     }
-- 
2.43.0