[NET] front: Allow copying receive path to be selected by user at

module load time.
Signed-off-by: Keir Fraser <keir@xensource.com>

diff --git a/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c b/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
index a257cb60643817367450ca9d9e429c314236acf5..44404afbcc5323c9aab8c63972dd895ef3398eab 100644 (file)
--- a/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
+++ b/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
@@ -63,6 +63,25 @@
 #include <xen/interface/grant_table.h>
 #include <xen/gnttab.h>
 
+/*
+ * Mutually-exclusive module options to select receive data path:
+ *  rx_copy : Packets are copied by network backend into local memory
+ *  rx_flip : Page containing packet data is transferred to our ownership
+ * For fully-virtualised guests there is no option - copying must be used.
+ * For paravirtualised guests, flipping is the default.
+ */
+#ifdef CONFIG_XEN
+static int MODPARM_rx_copy = 0;
+module_param_named(rx_copy, MODPARM_rx_copy, bool, 0);
+MODULE_PARM_DESC(rx_copy, "Copy packets from network card (rather than flip)");
+static int MODPARM_rx_flip = 0;
+module_param_named(rx_flip, MODPARM_rx_flip, bool, 0);
+MODULE_PARM_DESC(rx_flip, "Flip packets from network card (rather than copy)");
+#else
+static const int MODPARM_rx_copy = 1;
+static const int MODPARM_rx_flip = 0;
+#endif
+
 #define RX_COPY_THRESHOLD 256
 
 /* If we don't have GSO, fake things up so that we never try to use it. */
@@ -229,8 +248,7 @@ static int __devinit netfront_probe(struct xenbus_device *dev,
        int err;
        struct net_device *netdev;
        struct netfront_info *info;
-       unsigned int handle;
-       unsigned feature_rx_copy;
+       unsigned int handle, feature_rx_copy, feature_rx_flip, use_copy;
 
        err = xenbus_scanf(XBT_NIL, dev->nodename, "handle", "%u", &handle);
        if (err != 1) {
@@ -238,22 +256,24 @@ static int __devinit netfront_probe(struct xenbus_device *dev,
                return err;
        }
 
-#ifndef CONFIG_XEN
        err = xenbus_scanf(XBT_NIL, dev->otherend, "feature-rx-copy", "%u",
                           &feature_rx_copy);
-       if (err != 1) {
-               xenbus_dev_fatal(dev, err, "reading feature-rx-copy");
-               return err;
-       }
-       if (!feature_rx_copy) {
-               xenbus_dev_fatal(dev, 0, "need a copy-capable backend");
-               return -EINVAL;
-       }
-#else
-       feature_rx_copy = 0;
-#endif
+       if (err != 1)
+               feature_rx_copy = 0;
+       err = xenbus_scanf(XBT_NIL, dev->otherend, "feature-rx-flip", "%u",
+                          &feature_rx_flip);
+       if (err != 1)
+               feature_rx_flip = 1;
+
+       /*
+        * Copy packets on receive path if:
+        *  (a) This was requested by user, and the backend supports it; or
+        *  (b) Flipping was requested, but this is unsupported by the backend.
+        */
+       use_copy = (MODPARM_rx_copy && feature_rx_copy) ||
+               (MODPARM_rx_flip && !feature_rx_flip);
 
-       netdev = create_netdev(handle, feature_rx_copy, dev);
+       netdev = create_netdev(handle, use_copy, dev);
        if (IS_ERR(netdev)) {
                err = PTR_ERR(netdev);
                xenbus_dev_fatal(dev, err, "creating netdev");
@@ -271,6 +291,9 @@ static int __devinit netfront_probe(struct xenbus_device *dev,
        if (err)
                goto fail_open;
 
+       IPRINTK("Created netdev %s with %sing receive path.\n",
+               netdev->name, info->copying_receiver ? "copy" : "flipp");
+
        return 0;
 
  fail_open:
@@ -742,7 +765,7 @@ no_skb:
                } else {
                        gnttab_grant_foreign_access_ref(ref,
                                                        np->xbdev->otherend_id,
-                                                       pfn,
+                                                       pfn_to_mfn(pfn),
                                                        0);
                }
 
@@ -1632,7 +1655,8 @@ static void network_connect(struct net_device *dev)
                } else {
                        gnttab_grant_foreign_access_ref(
                                ref, np->xbdev->otherend_id,
-                               page_to_pfn(skb_shinfo(skb)->frags->page),
+                               pfn_to_mfn(page_to_pfn(skb_shinfo(skb)->
+                                                      frags->page)),
                                0);
                }
                req->gref = ref;
@@ -2053,6 +2077,16 @@ static int __init netif_init(void)
        if (!is_running_on_xen())
                return -ENODEV;
 
+#ifdef CONFIG_XEN
+       if (MODPARM_rx_flip && MODPARM_rx_copy) {
+               WPRINTK("Cannot specify both rx_copy and rx_flip.\n");
+               return -EINVAL;
+       }
+
+       if (!MODPARM_rx_flip && !MODPARM_rx_copy)
+               MODPARM_rx_flip = 1; /* Default is to flip. */
+#endif
+
        if (is_initial_xendomain())
                return 0;
 

diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
index e2eac58487e14c25b6dd7d951be1a4994a786d2a..b09bc2b850032b119a365a0ea3ea2b77f7b0f03d 100644 (file)
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -903,7 +903,7 @@ __gnttab_copy(
     }
     if ( !get_page_and_type(mfn_to_page(d_frame), dd, PGT_writable_page) )
         PIN_FAIL(error_out, GNTST_general_error,
-                 "could not get source frame %lx.\n", d_frame);
+                 "could not get destination frame %lx.\n", d_frame);
 
     sp = map_domain_page(s_frame);
     dp = map_domain_page(d_frame);