Tools: Remove shared page from mem_event/access/paging interfaces

Don't use the superfluous shared page, return the event channel directly as
part of the domctl struct, instead.

In-tree consumers (xenpaging, xen-access) updated. This is an ABI/API change,
so please voice any concerns.

Known pending issues:
- pager could die and its ring page could be used by some other process, yet
  Xen retains the mapping to it.
- use a saner interface for the paging_load buffer.

This change also affects the x86/mm bits in the hypervisor that process the
mem_event setup domctl.

Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Acked-by: Tim Deegan <tim@xen.org>
Acked-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Tim Deegan <tim@xen.org>

1 files changed, 7 insertions, 5 deletions

diff --git a/tools/libxc/xc_mem_event.c b/tools/libxc/xc_mem_event.c
index a568a52e77..fcca47c764 100644
--- a/tools/libxc/xc_mem_event.c
+++ b/tools/libxc/xc_mem_event.c
@@ -24,19 +24,21 @@
 #include "xc_private.h"
 
 int xc_mem_event_control(xc_interface *xch, domid_t domain_id, unsigned int op,
-                         unsigned int mode, void *page, void *ring_page)
+                         unsigned int mode, uint32_t *port, void *ring_page)
 {
     DECLARE_DOMCTL;
+    int rc;
 
     domctl.cmd = XEN_DOMCTL_mem_event_op;
     domctl.domain = domain_id;
     domctl.u.mem_event_op.op = op;
     domctl.u.mem_event_op.mode = mode;
-
-    domctl.u.mem_event_op.shared_addr = (unsigned long)page;
-    domctl.u.mem_event_op.ring_addr = (unsigned long)ring_page;
+    domctl.u.mem_event_op.ring_addr = (unsigned long) ring_page;
     
-    return do_domctl(xch, &domctl);
+    rc = do_domctl(xch, &domctl);
+    if ( !rc && port )
+        *port = domctl.u.mem_event_op.port;
+    return rc;
 }
 
 int xc_mem_event_memop(xc_interface *xch, domid_t domain_id,