Reverse c/s 24757.  Breaks booting NetWare.

# HG changeset patch
# User Alex Zeffertt <alex.zeffertt@eu.citrix.com>
# Date 1328812412 0
# Node ID aae516b78fce679f9c367231b7a3891814fcfdbb
# Parent  585caf50a9260d3fc6a4ece0450d10d34e73489f

xenstored: use grant references instead of map_foreign_range

make xenstored use grantref rather than map_foreign_range (which can
only be used by privileged domains)

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

Previous versions of this patch have been sent to xen-devel. See
http://lists.xensource.com/archives/html/xen-devel/2008-07/msg00610.html
http://lists.xensource.com/archives/html/xen-devel/2009-03/msg01492.html

Signed-off-by: Diego Ongaro <diego.ongaro@citrix.com>
Signed-off-by: Alex Zeffertt <alex.zeffertt@eu.citrix.com>
Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>

Index: xen-4.2.0-testing/tools/xenstore/xenstored_domain.c
===================================================================
--- xen-4.2.0-testing.orig/tools/xenstore/xenstored_domain.c
+++ xen-4.2.0-testing/tools/xenstore/xenstored_domain.c
@@ -32,10 +32,8 @@
 #include "xenstored_watch.h"
 
 #include <xenctrl.h>
-#include <xen/grant_table.h>
 
 static xc_interface **xc_handle;
-xc_gnttab **xcg_handle;
 static evtchn_port_t virq_port;
 
 xc_evtchn *xce_handle = NULL;
@@ -165,26 +163,6 @@ static int readchn(struct connection *co
 	return len;
 }
 
-static void *map_interface(domid_t domid, unsigned long mfn)
-{
-	if (*xcg_handle != NULL) {
-		/* this is the preferred method */
-		return xc_gnttab_map_grant_ref(*xcg_handle, domid,
-			GNTTAB_RESERVED_XENSTORE, PROT_READ|PROT_WRITE);
-	} else {
-		return xc_map_foreign_range(*xc_handle, domid,
-			getpagesize(), PROT_READ|PROT_WRITE, mfn);
-	}
-}
-
-static void unmap_interface(void *interface)
-{
-	if (*xcg_handle != NULL)
-		xc_gnttab_munmap(*xcg_handle, interface, 1);
-	else
-		munmap(interface, getpagesize());
-}
-
 static int destroy_domain(void *_domain)
 {
 	struct domain *domain = _domain;
@@ -196,14 +174,8 @@ static int destroy_domain(void *_domain)
 			eprintf("> Unbinding port %i failed!\n", domain->port);
 	}
 
-	if (domain->interface) {
-		/* Domain 0 was mapped by dom0_init, so it must be unmapped
-		   using munmap() and not the grant unmap call. */
-		if (domain->domid == 0)
-			unmap_xenbus(domain->interface);
-		else
-			unmap_interface(domain->interface);
-	}
+	if (domain->interface)
+		munmap(domain->interface, getpagesize());
 
 	fire_watches(NULL, "@releaseDomain", false);
 
@@ -372,7 +344,9 @@ void do_introduce(struct connection *con
 	domain = find_domain_by_domid(domid);
 
 	if (domain == NULL) {
-		interface = map_interface(domid, mfn);
+		interface = xc_map_foreign_range(
+			*xc_handle, domid,
+			getpagesize(), PROT_READ|PROT_WRITE, mfn);
 		if (!interface) {
 			send_error(conn, errno);
 			return;
@@ -380,7 +354,7 @@ void do_introduce(struct connection *con
 		/* Hang domain off "in" until we're finished. */
 		domain = new_domain(in, domid, port);
 		if (!domain) {
-			unmap_interface(interface);
+			munmap(interface, getpagesize());
 			send_error(conn, errno);
 			return;
 		}
@@ -572,18 +546,6 @@ void do_reset_watches(struct connection
 	send_ack(conn, XS_RESET_WATCHES);
 }
 
-static int close_xc_handle(void *_handle)
-{
-	xc_interface_close(*(xc_interface**)_handle);
-	return 0;
-}
-
-static int close_xcg_handle(void *_handle)
-{
-	xc_gnttab_close(*(xc_gnttab **)_handle);
-	return 0;
-}
-
 /* Returns the implicit path of a connection (only domains have this) */
 const char *get_implicit_path(const struct connection *conn)
 {
@@ -633,18 +595,6 @@ void domain_init(void)
 	if (!*xc_handle)
 		barf_perror("Failed to open connection to hypervisor");
 
-	talloc_set_destructor(xc_handle, close_xc_handle);
-
-	xcg_handle = talloc(talloc_autofree_context(), xc_gnttab*);
-	if (!xcg_handle)
-		barf_perror("Failed to allocate domain gnttab handle");
-
-	*xcg_handle = xc_gnttab_open(NULL, 0);
-	if (*xcg_handle < 0)
-		xprintf("WARNING: Failed to open connection to gnttab\n");
-	else
-		talloc_set_destructor(xcg_handle, close_xcg_handle);
-
 	xce_handle = xc_evtchn_open(NULL, 0);
 
 	if (xce_handle == NULL)