xen/x86: account number of foreign mappings in the p2m

Such information will be needed in order to remove foreign mappings during
teardown for HVM guests.

Right now the introduced counter is not consumed.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Release-acked-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>

diff --git a/xen/arch/x86/include/asm/p2m.h b/xen/arch/x86/include/asm/p2m.h
index 111badf89a6e55fbe0d5cc30854c973ba95f2344..107b9f260848af018fd9452b1470372b9f588ad4 100644 (file)
--- a/xen/arch/x86/include/asm/p2m.h
+++ b/xen/arch/x86/include/asm/p2m.h
@@ -380,6 +380,9 @@ struct p2m_domain {
         unsigned int flags;
         unsigned long entry_count;
     } ioreq;
+
+    /* Number of foreign mappings. */
+    unsigned long      nr_foreign;
 #endif /* CONFIG_HVM */
 };
 
@@ -1049,6 +1052,8 @@ static inline int p2m_entry_modify(struct p2m_domain *p2m, p2m_type_t nt,
         if ( !page_get_owner_and_reference(mfn_to_page(nfn)) )
             return -EBUSY;
 
+        p2m->nr_foreign++;
+
         break;
 
     default:
@@ -1069,6 +1074,7 @@ static inline int p2m_entry_modify(struct p2m_domain *p2m, p2m_type_t nt,
             return -EINVAL;
         }
         put_page(mfn_to_page(ofn));
+        p2m->nr_foreign--;
         break;
 
     default: