[PATCH RFC 2/5] Grant table for console, xenstore pages

[Diego Ongaro <diego.ongaro@citrix.com>]

This patch modifies the xenstore daemon to use xc_gnttab_map_grant_ref
instead of xc_map_foreign_range.

Make sure you have linux-2.6.18-xen.hg changeset 600:1bd3dbfdaf0f before
running this.

Signed-off-by: Diego Ongaro <diego.ongaro@citrix.com>
---
diff -r e4e473425d0f tools/xenstore/xenstored_domain.c
--- a/tools/xenstore/xenstored_domain.c	Thu Jul 10 19:05:56 2008 +0100
+++ b/tools/xenstore/xenstored_domain.c	Thu Jul 10 19:30:50 2008 +0100
@@ -31,8 +31,10 @@
 #include "xenstored_watch.h"
 
 #include <xenctrl.h>
+#include <xen/grant_table.h>
 
 static int *xc_handle;
+static int *xcg_handle;
 static evtchn_port_t virq_port;
 
 int xce_handle = -1; 
@@ -343,13 +345,14 @@
 	domain = find_domain_by_domid(domid);
 
 	if (domain == NULL) {
-		interface = xc_map_foreign_range(
-			*xc_handle, domid,
-			getpagesize(), PROT_READ|PROT_WRITE, mfn);
+		interface = xc_gnttab_map_grant_ref(*xcg_handle, domid,
+		                                    GNTTAB_RESERVED_XENSTORE,
+		                                    PROT_READ|PROT_WRITE);
 		if (!interface) {
 			send_error(conn, errno);
 			return;
 		}
+
 		/* Hang domain off "in" until we're finished. */
 		domain = new_domain(in, domid, port);
 		if (!domain) {
@@ -542,6 +545,12 @@
 	return 0;
 }
 
+static int close_xcg_handle(void *_handle)
+{
+	xc_gnttab_close(*(int *)_handle);
+	return 0;
+}
+
 /* Returns the implicit path of a connection (only domains have this) */
 const char *get_implicit_path(const struct connection *conn)
 {
@@ -593,6 +602,16 @@
 		barf_perror("Failed to open connection to hypervisor");
 
 	talloc_set_destructor(xc_handle, close_xc_handle);
+	
+	xcg_handle = talloc(talloc_autofree_context(), int);
+	if (!xcg_handle)
+		barf_perror("Failed to allocate domain gnttab handle");
+
+	*xcg_handle = xc_gnttab_open();
+	if (*xcg_handle < 0)
+		barf_perror("Failed to open gnttab connection to hypervisor");
+
+	talloc_set_destructor(xcg_handle, close_xcg_handle);
 
 	xce_handle = xc_evtchn_open();