Input: xen-kbdfront - add grant reference for shared page

Without a grant reference, full access to the domain's memory is
required to use the shared page. Add an additional parameter in
xenstore to allow grant mapping to be used.

Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Ian Campbell <Ian.Campbell@eu.citrix.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 28 insertions, 11 deletions

diff --git a/drivers/input/xen-kbdfront.c b/drivers/input/xen-kbdfront.c
index 53e62732ee96..7077f9bf5ead 100644
--- a/drivers/input/xen-kbdfront.c
+++ b/drivers/input/xen-kbdfront.c
@@ -11,12 +11,6 @@
  *  more details.
  */
 
-/*
- * TODO:
- *
- * Switch to grant tables together with xen-fbfront.c.
- */
-
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/kernel.h>
@@ -30,6 +24,8 @@
 #include <xen/xen.h>
 #include <xen/events.h>
 #include <xen/page.h>
+#include <xen/grant_table.h>
+#include <xen/interface/grant_table.h>
 #include <xen/interface/io/fbif.h>
 #include <xen/interface/io/kbdif.h>
 #include <xen/xenbus.h>
@@ -38,6 +34,7 @@ struct xenkbd_info {
         struct input_dev *kbd;
         struct input_dev *ptr;
         struct xenkbd_page *page;
+        int gref;
         int irq;
         struct xenbus_device *xbdev;
         char phys[32];
@@ -122,6 +119,7 @@ static int __devinit xenkbd_probe(struct xenbus_device *dev,
         dev_set_drvdata(&dev->dev, info);
         info->xbdev = dev;
         info->irq = -1;
+        info->gref = -1;
         snprintf(info->phys, sizeof(info->phys), "xenbus/%s", dev->nodename);
 
         info->page = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
@@ -232,15 +230,20 @@ static int xenkbd_connect_backend(struct xenbus_device *dev,
         int ret, evtchn;
         struct xenbus_transaction xbt;
 
+        ret = gnttab_grant_foreign_access(dev->otherend_id,
+                                          virt_to_mfn(info->page), 0);
+        if (ret < 0)
+                return ret;
+        info->gref = ret;
+
         ret = xenbus_alloc_evtchn(dev, &evtchn);
         if (ret)
-                return ret;
+                goto error_grant;
         ret = bind_evtchn_to_irqhandler(evtchn, input_handler,
                                         0, dev->devicetype, info);
         if (ret < 0) {
-                xenbus_free_evtchn(dev, evtchn);
                 xenbus_dev_fatal(dev, ret, "bind_evtchn_to_irqhandler");
-                return ret;
+                goto error_evtchan;
         }
         info->irq = ret;
 
@@ -248,12 +251,15 @@ static int xenkbd_connect_backend(struct xenbus_device *dev,
         ret = xenbus_transaction_start(&xbt);
         if (ret) {
                 xenbus_dev_fatal(dev, ret, "starting transaction");
-                return ret;
+                goto error_irqh;
         }
         ret = xenbus_printf(xbt, dev->nodename, "page-ref", "%lu",
                             virt_to_mfn(info->page));
         if (ret)
                 goto error_xenbus;
+        ret = xenbus_printf(xbt, dev->nodename, "page-gref", "%u", info->gref);
+        if (ret)
+                goto error_xenbus;
         ret = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
                             evtchn);
         if (ret)
@@ -263,7 +269,7 @@ static int xenkbd_connect_backend(struct xenbus_device *dev,
                 if (ret == -EAGAIN)
                         goto again;
                 xenbus_dev_fatal(dev, ret, "completing transaction");
-                return ret;
+                goto error_irqh;
         }
 
         xenbus_switch_state(dev, XenbusStateInitialised);
@@ -272,6 +278,14 @@ static int xenkbd_connect_backend(struct xenbus_device *dev,
  error_xenbus:
         xenbus_transaction_end(xbt, 1);
         xenbus_dev_fatal(dev, ret, "writing xenstore");
+ error_irqh:
+        unbind_from_irqhandler(info->irq, info);
+        info->irq = -1;
+ error_evtchan:
+        xenbus_free_evtchn(dev, evtchn);
+ error_grant:
+        gnttab_end_foreign_access_ref(info->gref, 0);
+        info->gref = -1;
         return ret;
 }
 
@@ -280,6 +294,9 @@ static void xenkbd_disconnect_backend(struct xenkbd_info *info)
         if (info->irq >= 0)
                 unbind_from_irqhandler(info->irq, info);
         info->irq = -1;
+        if (info->gref >= 0)
+                gnttab_end_foreign_access_ref(info->gref, 0);
+        info->gref = -1;
 }
 
 static void xenkbd_backend_changed(struct xenbus_device *dev,