diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
index da7d142ad8..c39e56f5b9 100644
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -1400,6 +1400,24 @@ static int range_share(struct domain *d, struct domain *cd,
     return rc;
 }
 
+static inline int mem_sharing_control(struct domain *d, bool enable)
+{
+    if ( enable )
+    {
+        if ( unlikely(!is_hvm_domain(d)) )
+            return -EOPNOTSUPP;
+
+        if ( unlikely(!hap_enabled(d)) )
+            return -ENODEV;
+
+        if ( unlikely(is_iommu_enabled(d)) )
+            return -EXDEV;
+    }
+
+    d->arch.hvm.mem_sharing.enabled = enable;
+    return 0;
+}
+
 int mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
 {
     int rc;
@@ -1421,10 +1439,8 @@ int mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
     if ( rc )
         goto out;
 
-    /* Only HAP is supported */
-    rc = -ENODEV;
-    if ( !mem_sharing_enabled(d) )
-        goto out;
+    if ( !mem_sharing_enabled(d) && (rc = mem_sharing_control(d, true)) )
+        return rc;
 
     switch ( mso.op )
     {
@@ -1432,10 +1448,6 @@ int mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
     {
         shr_handle_t handle;
 
-        rc = -EINVAL;
-        if ( !mem_sharing_enabled(d) )
-            goto out;
-
         rc = nominate_page(d, _gfn(mso.u.nominate.u.gfn), 0, &handle);
         mso.u.nominate.handle = handle;
     }
@@ -1447,9 +1459,6 @@ int mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
         gfn_t gfn;
         shr_handle_t handle;
 
-        rc = -EINVAL;
-        if ( !mem_sharing_enabled(d) )
-            goto out;
         rc = mem_sharing_gref_to_gfn(d->grant_table, gref, &gfn, NULL);
         if ( rc < 0 )
             goto out;
@@ -1465,10 +1474,6 @@ int mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
         struct domain *cd;
         shr_handle_t sh, ch;
 
-        rc = -EINVAL;
-        if ( !mem_sharing_enabled(d) )
-            goto out;
-
         rc = rcu_lock_live_remote_domain_by_id(mso.u.share.client_domain,
                                                &cd);
         if ( rc )
@@ -1535,10 +1540,6 @@ int mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
         struct domain *cd;
         shr_handle_t sh;
 
-        rc = -EINVAL;
-        if ( !mem_sharing_enabled(d) )
-            goto out;
-
         rc = rcu_lock_live_remote_domain_by_id(mso.u.share.client_domain,
                                                &cd);
         if ( rc )
@@ -1597,9 +1598,6 @@ int mem_sharing_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_sharing_op_t) arg)
               mso.u.range.opaque > mso.u.range.last_gfn) )
             goto out;
 
-        if ( !mem_sharing_enabled(d) )
-            goto out;
-
         rc = rcu_lock_live_remote_domain_by_id(mso.u.range.client_domain,
                                                &cd);
         if ( rc )
@@ -1691,18 +1689,10 @@ int mem_sharing_domctl(struct domain *d, struct xen_domctl_mem_sharing_op *mec)
 {
     int rc;
 
-    /* Only HAP is supported */
-    if ( !hap_enabled(d) )
-        return -ENODEV;
-
     switch ( mec->op )
     {
     case XEN_DOMCTL_MEM_SHARING_CONTROL:
-        rc = 0;
-        if ( unlikely(is_iommu_enabled(d) && mec->u.enable) )
-            rc = -EXDEV;
-        else
-            d->arch.hvm.mem_sharing_enabled = mec->u.enable;
+        rc = mem_sharing_control(d, mec->u.enable);
         break;
 
     default: