diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 7531406543..99816fc67c 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -4521,8 +4521,7 @@ int xenmem_add_to_physmap_one(
 
 int arch_acquire_resource(struct domain *d, unsigned int type,
                           unsigned int id, unsigned long frame,
-                          unsigned int nr_frames, xen_pfn_t mfn_list[],
-                          unsigned int *flags)
+                          unsigned int nr_frames, xen_pfn_t mfn_list[])
 {
     int rc;
 
diff --git a/xen/common/compat/memory.c b/xen/common/compat/memory.c
index 2eb79efa65..10a954f281 100644
--- a/xen/common/compat/memory.c
+++ b/xen/common/compat/memory.c
@@ -624,12 +624,6 @@ int compat_memory_op(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) compat)
                                              compat_frame_list,
                                              cmp.mar.nr_frames) )
                     return -EFAULT;
-
-                if ( __copy_field_to_guest(
-                         guest_handle_cast(compat,
-                                           compat_mem_acquire_resource_t),
-                         &cmp.mar, flags) )
-                    return -EFAULT;
             }
 
             break;
diff --git a/xen/common/memory.c b/xen/common/memory.c
index d9b35a608c..d5aff83f2d 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -1060,7 +1060,7 @@ static int acquire_resource(
     if ( copy_from_guest(&xmar, arg, 1) )
         return -EFAULT;
 
-    if ( xmar.flags != 0 )
+    if ( xmar.pad != 0 )
         return -EINVAL;
 
     if ( guest_handle_is_null(xmar.frame_list) )
@@ -1096,7 +1096,7 @@ static int acquire_resource(
 
     default:
         rc = arch_acquire_resource(d, xmar.type, xmar.id, xmar.frame,
-                                   xmar.nr_frames, mfn_list, &xmar.flags);
+                                   xmar.nr_frames, mfn_list);
         break;
     }
 
@@ -1116,11 +1116,9 @@ static int acquire_resource(
         /*
          * FIXME: Until foreign pages inserted into the P2M are properly
          *        reference counted, it is unsafe to allow mapping of
-         *        non-caller-owned resource pages unless the caller is
-         *        the hardware domain.
+         *        resource pages unless the caller is the hardware domain.
          */
-        if ( !(xmar.flags & XENMEM_rsrc_acq_caller_owned) &&
-             !is_hardware_domain(currd) )
+        if ( !is_hardware_domain(currd) )
             return -EACCES;
 
         if ( copy_from_guest(gfn_list, xmar.frame_list, xmar.nr_frames) )
@@ -1136,10 +1134,6 @@ static int acquire_resource(
         }
     }
 
-    if ( xmar.flags != 0 &&
-         __copy_field_to_guest(arg, &xmar, flags) )
-        rc = -EFAULT;
-
  out:
     rcu_unlock_domain(d);
 
diff --git a/xen/include/asm-arm/mm.h b/xen/include/asm-arm/mm.h
index 126e6be9b5..262d92f18d 100644
--- a/xen/include/asm-arm/mm.h
+++ b/xen/include/asm-arm/mm.h
@@ -358,7 +358,7 @@ void clear_and_clean_page(struct page_info *page);
 static inline
 int arch_acquire_resource(struct domain *d, unsigned int type, unsigned int id,
                           unsigned long frame, unsigned int nr_frames,
-                          xen_pfn_t mfn_list[], unsigned int *flags)
+                          xen_pfn_t mfn_list[])
 {
     return -EOPNOTSUPP;
 }
diff --git a/xen/include/asm-x86/mm.h b/xen/include/asm-x86/mm.h
index 790a2622ce..3863e4ce57 100644
--- a/xen/include/asm-x86/mm.h
+++ b/xen/include/asm-x86/mm.h
@@ -628,7 +628,6 @@ static inline bool arch_mfn_in_directmap(unsigned long mfn)
 
 int arch_acquire_resource(struct domain *d, unsigned int type,
                           unsigned int id, unsigned long frame,
-                          unsigned int nr_frames, xen_pfn_t mfn_list[],
-                          unsigned int *flags);
+                          unsigned int nr_frames, xen_pfn_t mfn_list[]);
 
 #endif /* __ASM_X86_MM_H__ */
diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h
index 68ddadbea8..cfdda6e2a8 100644
--- a/xen/include/public/memory.h
+++ b/xen/include/public/memory.h
@@ -632,16 +632,7 @@ struct xen_mem_acquire_resource {
      *          maximum value supported by the implementation on return.
      */
     uint32_t nr_frames;
-    /*
-     * OUT - Must be zero on entry. On return this may contain a bitwise
-     *       OR of the following values.
-     */
-    uint32_t flags;
-
-    /* The resource pages have been assigned to the calling domain */
-#define _XENMEM_rsrc_acq_caller_owned 0
-#define XENMEM_rsrc_acq_caller_owned (1u << _XENMEM_rsrc_acq_caller_owned)
-
+    uint32_t pad;
     /*
      * IN - the index of the initial frame to be mapped. This parameter
      *      is ignored if nr_frames is 0.