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>

2 files changed, 3 insertions, 16 deletions

diff --git a/tools/xenpaging/xenpaging.c b/tools/xenpaging/xenpaging.c
index c0f08e3c4c..06ccdd9960 100644
--- a/tools/xenpaging/xenpaging.c
+++ b/tools/xenpaging/xenpaging.c
@@ -337,14 +337,6 @@ static struct xenpaging *xenpaging_init(int argc, char *argv[])
         goto err;
     }
 
-    /* Initialise shared page */
-    paging->mem_event.shared_page = init_page();
-    if ( paging->mem_event.shared_page == NULL )
-    {
-        PERROR("Error initialising shared page");
-        goto err;
-    }
-
     /* Initialise ring page */
     paging->mem_event.ring_page = init_page();
     if ( paging->mem_event.ring_page == NULL )
@@ -361,7 +353,7 @@ static struct xenpaging *xenpaging_init(int argc, char *argv[])
     
     /* Initialise Xen */
     rc = xc_mem_paging_enable(xch, paging->mem_event.domain_id,
-                             paging->mem_event.shared_page,
+                             &paging->mem_event.evtchn_port, 
                              paging->mem_event.ring_page);
     if ( rc != 0 )
     {
@@ -393,7 +385,7 @@ static struct xenpaging *xenpaging_init(int argc, char *argv[])
     /* Bind event notification */
     rc = xc_evtchn_bind_interdomain(paging->mem_event.xce_handle,
                                     paging->mem_event.domain_id,
-                                    paging->mem_event.shared_page->port);
+                                    paging->mem_event.evtchn_port);
     if ( rc < 0 )
     {
         PERROR("Failed to bind event channel");
@@ -474,11 +466,6 @@ static struct xenpaging *xenpaging_init(int argc, char *argv[])
             munlock(paging->paging_buffer, PAGE_SIZE);
             free(paging->paging_buffer);
         }
-        if ( paging->mem_event.shared_page )
-        {
-            munlock(paging->mem_event.shared_page, PAGE_SIZE);
-            free(paging->mem_event.shared_page);
-        }
 
         if ( paging->mem_event.ring_page )
         {
diff --git a/tools/xenpaging/xenpaging.h b/tools/xenpaging/xenpaging.h
index e348db63c5..5a300c755c 100644
--- a/tools/xenpaging/xenpaging.h
+++ b/tools/xenpaging/xenpaging.h
@@ -36,7 +36,7 @@ struct mem_event {
     xc_evtchn *xce_handle;
     int port;
     mem_event_back_ring_t back_ring;
-    mem_event_shared_page_t *shared_page;
+    uint32_t evtchn_port;
     void *ring_page;
 };