[PATCH 4 of 5] Adds a separate domctl for performing sharing audits

[Andres Lagar-Cavilla <andres@lagarcavilla.org>]

 xen/arch/x86/mm/mem_sharing.c |  17 ++++++++++++-----
 xen/include/public/domctl.h   |   1 +
 2 files changed, 13 insertions(+), 5 deletions(-)


Sharing audits are heavyweight, so instead of performing them inline,
we make them callable via a domctl.

Signed-off-by: Adin Scannell <adin@scannell.ca>

diff -r 536da18b7ab6 -r a79bb54cb4dc xen/arch/x86/mm/mem_sharing.c
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -820,7 +820,6 @@ int mem_sharing_unshare_page(struct doma
      * between shr_lock and p2m fine-grained locks in mm-lock. 
      * Callers may walk in here already holding the lock for this gfn */
     shr_lock();
-    mem_sharing_audit();
     mfn = get_gfn(d, gfn, &p2mt);
     
     /* Has someone already unshared it? */
@@ -1117,15 +1116,23 @@ int mem_sharing_domctl(struct domain *d,
         }
         break;
 
+        case XEN_DOMCTL_MEM_EVENT_OP_SHARING_AUDIT:
+        {
+#if MEM_SHARING_AUDIT
+            shr_lock();
+            rc = mem_sharing_audit();
+            shr_unlock();
+#else
+            rc = -ENOSYS;
+#endif
+            break;
+        }
+
         default:
             rc = -ENOSYS;
             break;
     }
 
-    shr_lock();
-    mem_sharing_audit();
-    shr_unlock();
-
     return rc;
 }
 
diff -r 536da18b7ab6 -r a79bb54cb4dc xen/include/public/domctl.h
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -772,6 +772,7 @@ DEFINE_XEN_GUEST_HANDLE(xen_domctl_mem_e
 #define XEN_DOMCTL_MEM_EVENT_OP_SHARING_DEBUG_MFN      6
 #define XEN_DOMCTL_MEM_EVENT_OP_SHARING_DEBUG_GREF     7
 #define XEN_DOMCTL_MEM_EVENT_OP_SHARING_ADD_PHYSMAP    8
+#define XEN_DOMCTL_MEM_EVENT_OP_SHARING_AUDIT          9
 
 #define XEN_DOMCTL_MEM_SHARING_S_HANDLE_INVALID  (-10)
 #define XEN_DOMCTL_MEM_SHARING_C_HANDLE_INVALID  (-9)