xen: re-define assign_pages and introduce a new function assign_page

In order to deal with the trouble of count-to-order conversion when page number
is not in a power-of-two, this commit re-define assign_pages for nr pages and
assign_page for original page with a single order.

Backporting confusion could be helped by altering the order of assign_pages
parameters, such that the compiler would point out that adjustments at call
sites are needed.

[stefano: switch to unsigned int for nr]
Signed-off-by: Penny Zheng <penny.zheng@arm.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>

xen/arch/x86/pv/dom0_build.c

@@ -568,7 +568,7 @@ int __init dom0_construct_pv(struct domain *d,
         else
         {
             while ( count-- )
-                if ( assign_pages(d, mfn_to_page(_mfn(mfn++)), 0, 0) )
+                if ( assign_pages(mfn_to_page(_mfn(mfn++)), 1, d, 0) )
                     BUG();
         }
         initrd->mod_end = 0;

xen/common/grant_table.c

@@ -2358,7 +2358,7 @@ gnttab_transfer(
          * is respected and speculative execution is blocked accordingly
          */
         if ( unlikely(!evaluate_nospec(okay)) ||
-            unlikely(assign_pages(e, page, 0, MEMF_no_refcount)) )
+            unlikely(assign_pages(page, 1, e, MEMF_no_refcount)) )
         {
             bool drop_dom_ref;
 

xen/common/memory.c

@@ -728,7 +728,7 @@ static long memory_exchange(XEN_GUEST_HANDLE_PARAM(xen_memory_exchange_t) arg)
         /* Assign each output page to the domain. */
         for ( j = 0; (page = page_list_remove_head(&out_chunk_list)); ++j )
         {
-            if ( assign_pages(d, page, exch.out.extent_order,
+            if ( assign_page(page, exch.out.extent_order, d,
                              MEMF_no_refcount) )
             {
                 unsigned long dec_count;
@@ -797,7 +797,7 @@ static long memory_exchange(XEN_GUEST_HANDLE_PARAM(xen_memory_exchange_t) arg)
      * cleared PGC_allocated.
      */
     while ( (page = page_list_remove_head(&in_chunk_list)) )
-        if ( assign_pages(d, page, 0, MEMF_no_refcount) )
+        if ( assign_pages(page, 1, d, MEMF_no_refcount) )
         {
             BUG_ON(!d->is_dying);
             free_domheap_page(page);

xen/common/page_alloc.c

@@ -2259,9 +2259,9 @@ void init_domheap_pages(paddr_t ps, paddr_t pe)
 
 
 int assign_pages(
-    struct domain *d,
     struct page_info *pg,
-    unsigned int order,
+    unsigned int nr,
+    struct domain *d,
     unsigned int memflags)
 {
     int rc = 0;
@@ -2281,7 +2281,7 @@ int assign_pages(
     {
         unsigned int extra_pages = 0;
 
-        for ( i = 0; i < (1ul << order); i++ )
+        for ( i = 0; i < nr; i++ )
         {
             ASSERT(!(pg[i].count_info & ~PGC_extra));
             if ( pg[i].count_info & PGC_extra )
@@ -2290,18 +2290,18 @@ int assign_pages(
 
         ASSERT(!extra_pages ||
                ((memflags & MEMF_no_refcount) &&
-                extra_pages == 1u << order));
+                extra_pages == nr));
     }
 #endif
 
     if ( pg[0].count_info & PGC_extra )
     {
-        d->extra_pages += 1u << order;
+        d->extra_pages += nr;
         memflags &= ~MEMF_no_refcount;
     }
     else if ( !(memflags & MEMF_no_refcount) )
     {
-        unsigned int tot_pages = domain_tot_pages(d) + (1 << order);
+        unsigned int tot_pages = domain_tot_pages(d) + nr;
 
         if ( unlikely(tot_pages > d->max_pages) )
         {
@@ -2313,10 +2313,10 @@ int assign_pages(
     }
 
     if ( !(memflags & MEMF_no_refcount) &&
-         unlikely(domain_adjust_tot_pages(d, 1 << order) == (1 << order)) )
+         unlikely(domain_adjust_tot_pages(d, nr) == nr) )
         get_knownalive_domain(d);
 
-    for ( i = 0; i < (1 << order); i++ )
+    for ( i = 0; i < nr; i++ )
     {
         ASSERT(page_get_owner(&pg[i]) == NULL);
         page_set_owner(&pg[i], d);
@@ -2331,6 +2331,11 @@ int assign_pages(
     return rc;
 }
 
+int assign_page(struct page_info *pg, unsigned int order, struct domain *d,
+                unsigned int memflags)
+{
+    return assign_pages(pg, 1UL << order, d, memflags);
+}
 
 struct page_info *alloc_domheap_pages(
     struct domain *d, unsigned int order, unsigned int memflags)
@@ -2373,7 +2378,7 @@ struct page_info *alloc_domheap_pages(
                 pg[i].count_info = PGC_extra;
             }
         }
-        if ( assign_pages(d, pg, order, memflags) )
+        if ( assign_page(pg, order, d, memflags) )
         {
             free_heap_pages(pg, order, memflags & MEMF_no_scrub);
             return NULL;

xen/include/xen/mm.h

@@ -132,9 +132,15 @@ int query_page_offline(mfn_t mfn, uint32_t *status);
 void heap_init_late(void);
 
 int assign_pages(
+    struct page_info *pg,
+    unsigned int nr,
     struct domain *d,
+    unsigned int memflags);
+
+int assign_page(
     struct page_info *pg,
     unsigned int order,
+    struct domain *d,
     unsigned int memflags);
 
 /* Dump info to serial console */