x86/mm: wire up sharing ring

Now that we have an interface close to finalizing, do the necessary plumbing to
set up a ring for reporting failed allocations in the unshare path.

Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Acked-by: Tim Deegan <tim@xen.org>
Committed-by: Tim Deegan <tim@xen.org>

1 files changed, 19 insertions, 1 deletions

diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index a3ed8d76be..494520743d 100644
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -711,7 +711,7 @@ struct xen_domctl_gdbsx_domstatus {
 /* XEN_DOMCTL_mem_event_op */
 
 /*
-* Domain memory paging
+ * Domain memory paging
  * Page memory in and out.
  * Domctl interface to set up and tear down the 
  * pager<->hypervisor interface. Use XENMEM_paging_op*
@@ -741,6 +741,24 @@ struct xen_domctl_gdbsx_domstatus {
 #define XEN_DOMCTL_MEM_EVENT_OP_ACCESS_ENABLE     0
 #define XEN_DOMCTL_MEM_EVENT_OP_ACCESS_DISABLE    1
 
+/*
+ * Sharing ENOMEM helper.
+ *
+ * As with paging, use the domctl for teardown/setup of the
+ * helper<->hypervisor interface.
+ *
+ * If setup, this ring is used to communicate failed allocations
+ * in the unshare path. XENMEM_sharing_op_resume is used to wake up
+ * vcpus that could not unshare.
+ *
+ * Note that shring can be turned on (as per the domctl below)
+ * *without* this ring being setup.
+ */
+#define XEN_DOMCTL_MEM_EVENT_OP_SHARING           3
+
+#define XEN_DOMCTL_MEM_EVENT_OP_SHARING_ENABLE    0
+#define XEN_DOMCTL_MEM_EVENT_OP_SHARING_DISABLE   1
+
 /* Use for teardown/setup of helper<->hypervisor interface for paging, 
  * access and sharing.*/
 struct xen_domctl_mem_event_op {