# HG changeset patch
# Parent a4d7c27ec1f190ecbb9a909609f6ef0eca250c00
xenpaging: extend xc_mem_paging_enable() to handle interface version

Since upcoming patches will change the way how paging internally works, add a
new interface to xc_mem_paging_enable() to make sure the pager is not
out-of-date. This is similar to XEN_DOMCTL_INTERFACE_VERSION in do_domctl()
where the tools have to match the running hypervisor.

Signed-off-by: Olaf Hering <olaf@aepfle.de>

Index: xen-4.1.2-testing/tools/libxc/xc_mem_paging.c
===================================================================
--- xen-4.1.2-testing.orig/tools/libxc/xc_mem_paging.c
+++ xen-4.1.2-testing/tools/libxc/xc_mem_paging.c
@@ -25,12 +25,13 @@
 
 
 int xc_mem_paging_enable(xc_interface *xch, domid_t domain_id,
+                        unsigned long interface_age,
                         void *shared_page, void *ring_page)
 {
     return xc_mem_event_control(xch, domain_id,
                                 XEN_DOMCTL_MEM_EVENT_OP_PAGING_ENABLE,
                                 XEN_DOMCTL_MEM_EVENT_OP_PAGING,
-                                shared_page, ring_page, INVALID_MFN);
+                                shared_page, ring_page, interface_age);
 }
 
 int xc_mem_paging_disable(xc_interface *xch, domid_t domain_id)
Index: xen-4.1.2-testing/tools/libxc/xenctrl.h
===================================================================
--- xen-4.1.2-testing.orig/tools/libxc/xenctrl.h
+++ xen-4.1.2-testing/tools/libxc/xenctrl.h
@@ -1736,6 +1736,7 @@ int xc_mem_event_control(xc_interface *x
                           void *ring_page, unsigned long gfn);
 
 int xc_mem_paging_enable(xc_interface *xch, domid_t domain_id,
+                        unsigned long interface_age,
                         void *shared_page, void *ring_page);
 int xc_mem_paging_disable(xc_interface *xch, domid_t domain_id);
 int xc_mem_paging_nominate(xc_interface *xch, domid_t domain_id,
Index: xen-4.1.2-testing/tools/xenpaging/xenpaging.c
===================================================================
--- xen-4.1.2-testing.orig/tools/xenpaging/xenpaging.c
+++ xen-4.1.2-testing/tools/xenpaging/xenpaging.c
@@ -366,6 +366,7 @@ static xenpaging_t *xenpaging_init(int a
     
     /* Initialise Xen */
     rc = xc_mem_paging_enable(xch, paging->mem_event.domain_id,
+                             MEM_EVENT_PAGING_AGE,
                              paging->mem_event.shared_page,
                              paging->mem_event.ring_page);
     if ( rc != 0 )
Index: xen-4.1.2-testing/xen/arch/x86/mm/mem_event.c
===================================================================
--- xen-4.1.2-testing.orig/xen/arch/x86/mm/mem_event.c
+++ xen-4.1.2-testing/xen/arch/x86/mm/mem_event.c
@@ -274,6 +274,15 @@ int mem_event_domctl(struct domain *d, x
             if ( p2m->pod.entry_count )
                 break;
 
+            rc = -ENOEXEC;
+            /* Disallow paging in a PoD guest */
+            if ( mec->gfn != MEM_EVENT_PAGING_AGE )
+	    {
+                gdprintk(XENLOG_INFO, "Expected paging age %lx, got %lx\n",
+                         MEM_EVENT_PAGING_AGE, mec->gfn);
+                break;
+	    }
+
             rc = mem_event_enable(d, mec, med);
         }
         break;
Index: xen-4.1.2-testing/xen/include/public/mem_event.h
===================================================================
--- xen-4.1.2-testing.orig/xen/include/public/mem_event.h
+++ xen-4.1.2-testing/xen/include/public/mem_event.h
@@ -49,6 +49,8 @@
 #define MEM_EVENT_REASON_INT3        5    /* int3 was hit: gla/gfn are RIP */
 #define MEM_EVENT_REASON_SINGLESTEP  6    /* single step was invoked: gla/gfn are RIP */
 
+#define MEM_EVENT_PAGING_AGE         1UL  /* Number distinguish the mem_paging <-> pager interface */
+
 typedef struct mem_event_shared_page {
     uint32_t port;
 } mem_event_shared_page_t;