mem_access: mem event additions for access

* Adds an ACCESS memory event type, with RESUME as the action.

* Refactors the bits in the memory event to store whether the memory event
  was a read, write, or execute (for access memory events only).  I used
  bits sparingly to keep the structure somewhat the same size.

* Modified VMX to report the needed information in its nested page fault.
  SVM is not implemented in this patch series.

Signed-off-by: Joe Epstein <jepstein98@gmail.com>
Acked-by: Keir Fraser <keir@xen.org>
Acked-by: Tim Deegan <Tim.Deegan@citrix.com>

1 files changed, 14 insertions, 1 deletions

diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index 161dc7020d..06507bfaab 100644
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -714,7 +714,7 @@ struct xen_domctl_gdbsx_domstatus {
 /*
  * Page memory in and out. 
  */
-#define XEN_DOMCTL_MEM_EVENT_OP_PAGING (1 << 0)
+#define XEN_DOMCTL_MEM_EVENT_OP_PAGING            1
 
 /* Domain memory paging */
 #define XEN_DOMCTL_MEM_EVENT_OP_PAGING_NOMINATE   0
@@ -722,6 +722,19 @@ struct xen_domctl_gdbsx_domstatus {
 #define XEN_DOMCTL_MEM_EVENT_OP_PAGING_PREP       2
 #define XEN_DOMCTL_MEM_EVENT_OP_PAGING_RESUME     3
 
+/*
+ * Access permissions.
+ *
+ * There are HVM hypercalls to set the per-page access permissions of every
+ * page in a domain.  When one of these permissions--independent, read, 
+ * write, and execute--is violated, the VCPU is paused and a memory event 
+ * is sent with what happened.  (See public/mem_event.h)  The memory event 
+ * handler can then resume the VCPU and redo the access with an 
+ * ACCESS_RESUME mode for the following domctl.
+ */
+#define XEN_DOMCTL_MEM_EVENT_OP_ACCESS            2
+#define XEN_DOMCTL_MEM_EVENT_OP_ACCESS_RESUME     0 
+
 struct xen_domctl_mem_event_op {
     uint32_t       op;           /* XEN_DOMCTL_MEM_EVENT_OP_* */
     uint32_t       mode;         /* XEN_DOMCTL_MEM_EVENT_ENABLE_* */