xen/vmap: Introduce vmap_size() and use it

vunmap() and vfree() currently duplicate the (small) logic to find the
size of an vmap area. In a follow-up patch, we will want to introduce
another one (this time externally).

So introduce a new helper vmap_size() that will return the number of
pages in the area starting at the given address. Take the opportunity
to replace the open-coded version.

Note that vfree() was storing the type of the area in a local variable.
But this seems to have never been used (even when it was introduced).

Signed-off-by: Julien Grall <jgrall@amazon.com>
Signed-off-by: Elias El Yandouzi <eliasely@amazon.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/common/vmap.c

@@ -245,14 +245,21 @@ void *vmap(const mfn_t *mfn, unsigned int nr)
     return __vmap(mfn, 1, nr, 1, PAGE_HYPERVISOR, VMAP_DEFAULT);
 }
 
-void vunmap(const void *va)
+unsigned int vmap_size(const void *va)
 {
-    unsigned long addr = (unsigned long)va;
     unsigned int pages = vm_size(va, VMAP_DEFAULT);
 
     if ( !pages )
         pages = vm_size(va, VMAP_XEN);
 
+    return pages;
+}
+
+void vunmap(const void *va)
+{
+    unsigned long addr = (unsigned long)va;
+    unsigned pages = vmap_size(va);
+
 #ifndef _PAGE_NONE
     destroy_xen_mappings(addr, addr + PAGE_SIZE * pages);
 #else /* Avoid tearing down intermediate page tables. */
@@ -328,17 +335,11 @@ void vfree(void *va)
     unsigned int i, pages;
     struct page_info *pg;
     PAGE_LIST_HEAD(pg_list);
-    enum vmap_region type = VMAP_DEFAULT;
 
     if ( !va )
         return;
 
-    pages = vm_size(va, type);
-    if ( !pages )
-    {
-        type = VMAP_XEN;
-        pages = vm_size(va, type);
-    }
+    pages = vmap_size(va);
     ASSERT(pages);
 
     for ( i = 0; i < pages; i++ )

xen/include/xen/vmap.h

@@ -25,6 +25,9 @@ void vfree(void *va);
 
 void __iomem *ioremap(paddr_t pa, size_t len);
 
+/* Return the number of pages in the mapping starting at address 'va' */
+unsigned int vmap_size(const void *va);
+
 static inline void iounmap(void __iomem *va)
 {
     unsigned long addr = (unsigned long)(void __force *)va;