Allow VMs to query their own grant table version.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Committed-by: Keir Fraser <keir@xen.org>

1 files changed, 9 insertions, 10 deletions

diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
index fefa8383b2..014734d240 100644
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -2253,30 +2253,29 @@ gnttab_get_version(XEN_GUEST_HANDLE(gnttab_get_version_t uop))
 {
     gnttab_get_version_t op;
     struct domain *d;
+    int rc;
 
     if ( copy_from_guest(&op, uop, 1) )
         return -EFAULT;
-    d = rcu_lock_domain_by_id(op.dom);
-    if ( d == NULL )
-        return -ESRCH;
-    if ( !IS_PRIV_FOR(current->domain, d) )
-    {
-        rcu_unlock_domain(d);
-        return -EPERM;
-    }
+
+    rc = rcu_lock_target_domain_by_id(op.dom, &d);
+    if ( rc < 0 )
+        return rc;
+
     if ( xsm_grant_query_size(current->domain, d) )
     {
         rcu_unlock_domain(d);
         return -EPERM;
     }
+
     spin_lock(&d->grant_table->lock);
     op.version = d->grant_table->gt_version;
     spin_unlock(&d->grant_table->lock);
 
     if ( copy_to_guest(uop, &op, 1) )
         return -EFAULT;
-    else
-        return 0;
+
+    return 0;
 }
 
 long