x86/mm: Use flags for _put_page_type rather than a boolean

This is in mainly in preparation for _put_page_type taking the
partial_flags value in the future.  It also makes it easier to read in
the caller (since you see a flag name rather than `true` or `false`).

No functional change intended.

This is part of XSA-299.

Reported-by: George Dunlap <george.dunlap@citrix.com>
Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/mm.c

@@ -1170,7 +1170,7 @@ get_page_from_l4e(
 }
 #endif /* CONFIG_PV */
 
-static int _put_page_type(struct page_info *page, bool preemptible,
+static int _put_page_type(struct page_info *page, unsigned int flags,
                           struct page_info *ptpg);
 
 void put_page_from_l1e(l1_pgentry_t l1e, struct domain *l1e_owner)
@@ -1290,7 +1290,7 @@ static int put_page_from_l2e(l2_pgentry_t l2e, unsigned long pfn,
               PTF_partial_set )
         {
             ASSERT(!(flags & PTF_defer));
-            rc = _put_page_type(pg, true, ptpg);
+            rc = _put_page_type(pg, PTF_preemptible, ptpg);
         }
         else if ( flags & PTF_defer )
         {
@@ -1299,7 +1299,7 @@ static int put_page_from_l2e(l2_pgentry_t l2e, unsigned long pfn,
         }
         else
         {
-            rc = _put_page_type(pg, true, ptpg);
+            rc = _put_page_type(pg, PTF_preemptible, ptpg);
             if ( likely(!rc) )
                 put_page(pg);
         }
@@ -1336,7 +1336,7 @@ static int put_page_from_l3e(l3_pgentry_t l3e, unsigned long pfn,
          PTF_partial_set )
     {
         ASSERT(!(flags & PTF_defer));
-        return _put_page_type(pg, true, mfn_to_page(_mfn(pfn)));
+        return _put_page_type(pg, PTF_preemptible, mfn_to_page(_mfn(pfn)));
     }
 
     if ( flags & PTF_defer )
@@ -1346,7 +1346,7 @@ static int put_page_from_l3e(l3_pgentry_t l3e, unsigned long pfn,
         return 0;
     }
 
-    rc = _put_page_type(pg, true, mfn_to_page(_mfn(pfn)));
+    rc = _put_page_type(pg, PTF_preemptible, mfn_to_page(_mfn(pfn)));
     if ( likely(!rc) )
         put_page(pg);
 
@@ -1367,7 +1367,7 @@ static int put_page_from_l4e(l4_pgentry_t l4e, unsigned long pfn,
               PTF_partial_set )
         {
             ASSERT(!(flags & PTF_defer));
-            return _put_page_type(pg, true, mfn_to_page(_mfn(pfn)));
+            return _put_page_type(pg, PTF_preemptible, mfn_to_page(_mfn(pfn)));
         }
 
         if ( flags & PTF_defer )
@@ -1377,7 +1377,7 @@ static int put_page_from_l4e(l4_pgentry_t l4e, unsigned long pfn,
             return 0;
         }
 
-        rc = _put_page_type(pg, true, mfn_to_page(_mfn(pfn)));
+        rc = _put_page_type(pg, PTF_preemptible, mfn_to_page(_mfn(pfn)));
         if ( likely(!rc) )
             put_page(pg);
     }
@@ -2727,10 +2727,11 @@ static int _put_final_page_type(struct page_info *page, unsigned long type,
 }
 
 
-static int _put_page_type(struct page_info *page, bool preemptible,
+static int _put_page_type(struct page_info *page, unsigned int flags,
                           struct page_info *ptpg)
 {
     unsigned long nx, x, y = page->u.inuse.type_info;
+    bool preemptible = flags & PTF_preemptible;
 
     ASSERT(current_locked_page_ne_check(page));
 
@@ -2936,7 +2937,7 @@ static int _get_page_type(struct page_info *page, unsigned long type,
 
             if ( unlikely(rc) )
             {
-                _put_page_type(page, false, NULL);
+                _put_page_type(page, 0, NULL);
                 goto out;
             }
         }
@@ -2962,7 +2963,7 @@ static int _get_page_type(struct page_info *page, unsigned long type,
 
 void put_page_type(struct page_info *page)
 {
-    int rc = _put_page_type(page, false, NULL);
+    int rc = _put_page_type(page, 0, NULL);
     ASSERT(rc == 0);
     (void)rc;
 }
@@ -2979,7 +2980,7 @@ int get_page_type(struct page_info *page, unsigned long type)
 
 int put_page_type_preemptible(struct page_info *page)
 {
-    return _put_page_type(page, true, NULL);
+    return _put_page_type(page, PTF_preemptible, NULL);
 }
 
 int get_page_type_preemptible(struct page_info *page, unsigned long type)
@@ -2996,7 +2997,7 @@ int put_old_guest_table(struct vcpu *v)
     if ( !v->arch.old_guest_table )
         return 0;
 
-    switch ( rc = _put_page_type(v->arch.old_guest_table, true,
+    switch ( rc = _put_page_type(v->arch.old_guest_table, PTF_preemptible,
                                  v->arch.old_guest_ptpg) )
     {
     case -EINTR: