xen networking: add XDP offset adjustment to xen-netback

the patch basically adds the offset adjustment and netfront
state reading to make XDP work on netfront side.

Reviewed-by: Paul Durrant <paul@xen.org>
Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index 05847eb91a1b4a24c29567384d0a1b7094f56235..ae477f7756af1a5236016dddd885c08b0258194e 100644 (file)
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -281,6 +281,9 @@ struct xenvif {
        u8 ipv6_csum:1;
        u8 multicast_control:1;
 
+       /* headroom requested by xen-netfront */
+       u16 xdp_headroom;
+
        /* Is this interface disabled? True when backend discovers
         * frontend is rogue.
         */
@@ -395,6 +398,7 @@ static inline pending_ring_idx_t nr_pending_reqs(struct xenvif_queue *queue)
 irqreturn_t xenvif_interrupt(int irq, void *dev_id);
 
 extern bool separate_tx_rx_irq;
+extern bool provides_xdp_headroom;
 
 extern unsigned int rx_drain_timeout_msecs;
 extern unsigned int rx_stall_timeout_msecs;

diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 0c8a02a1ead746e362c65984228e8b7dcd75f547..8af49728569151f86b9d3f2485b58cc5e0ebccda 100644 (file)
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -483,6 +483,8 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
        vif->queues = NULL;
        vif->num_queues = 0;
 
+       vif->xdp_headroom = 0;
+
        spin_lock_init(&vif->lock);
        INIT_LIST_HEAD(&vif->fe_mcast_addr);
 

diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 315dfc6ea29729285293525a2c66d461e99b645e..6dfca72656449be4dd3e2d1b3a20aabc32249653 100644 (file)
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -96,6 +96,13 @@ unsigned int xenvif_hash_cache_size = XENVIF_HASH_CACHE_SIZE_DEFAULT;
 module_param_named(hash_cache_size, xenvif_hash_cache_size, uint, 0644);
 MODULE_PARM_DESC(hash_cache_size, "Number of flows in the hash cache");
 
+/* The module parameter tells that we have to put data
+ * for xen-netfront with the XDP_PACKET_HEADROOM offset
+ * needed for XDP processing
+ */
+bool provides_xdp_headroom = true;
+module_param(provides_xdp_headroom, bool, 0644);
+
 static void xenvif_idx_release(struct xenvif_queue *queue, u16 pending_idx,
                               u8 status);
 

diff --git a/drivers/net/xen-netback/rx.c b/drivers/net/xen-netback/rx.c
index ef5887037b225251cfa77ccac587f79ad338dd9d..ac034f69a170b4bdb8e02c65305fbea85dd559aa 100644 (file)
--- a/drivers/net/xen-netback/rx.c
+++ b/drivers/net/xen-netback/rx.c
@@ -258,6 +258,19 @@ static void xenvif_rx_next_skb(struct xenvif_queue *queue,
                pkt->extra_count++;
        }
 
+       if (queue->vif->xdp_headroom) {
+               struct xen_netif_extra_info *extra;
+
+               extra = &pkt->extras[XEN_NETIF_EXTRA_TYPE_XDP - 1];
+
+               memset(extra, 0, sizeof(struct xen_netif_extra_info));
+               extra->u.xdp.headroom = queue->vif->xdp_headroom;
+               extra->type = XEN_NETIF_EXTRA_TYPE_XDP;
+               extra->flags = 0;
+
+               pkt->extra_count++;
+       }
+
        if (skb->sw_hash) {
                struct xen_netif_extra_info *extra;
 
@@ -356,7 +369,7 @@ static void xenvif_rx_data_slot(struct xenvif_queue *queue,
                                struct xen_netif_rx_request *req,
                                struct xen_netif_rx_response *rsp)
 {
-       unsigned int offset = 0;
+       unsigned int offset = queue->vif->xdp_headroom;
        unsigned int flags;
 
        do {

diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 286054b60d47432555f358442be11b37f8319980..7e62a6ee76223bea8c8eccb2298fc659ba6af2ee 100644 (file)
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -393,6 +393,24 @@ static void set_backend_state(struct backend_info *be,
        }
 }
 
+static void read_xenbus_frontend_xdp(struct backend_info *be,
+                                     struct xenbus_device *dev)
+{
+       struct xenvif *vif = be->vif;
+       u16 headroom;
+       int err;
+
+       err = xenbus_scanf(XBT_NIL, dev->otherend,
+                          "xdp-headroom", "%hu", &headroom);
+       if (err != 1) {
+               vif->xdp_headroom = 0;
+               return;
+       }
+       if (headroom > XEN_NETIF_MAX_XDP_HEADROOM)
+               headroom = XEN_NETIF_MAX_XDP_HEADROOM;
+       vif->xdp_headroom = headroom;
+}
+
 /**
  * Callback received when the frontend's state changes.
  */
@@ -417,6 +435,11 @@ static void frontend_changed(struct xenbus_device *dev,
                set_backend_state(be, XenbusStateConnected);
                break;
 
+       case XenbusStateReconfiguring:
+               read_xenbus_frontend_xdp(be, dev);
+               xenbus_switch_state(dev, XenbusStateReconfigured);
+               break;
+
        case XenbusStateClosing:
                set_backend_state(be, XenbusStateClosing);
                break;
@@ -947,6 +970,8 @@ static int read_xenbus_vif_flags(struct backend_info *be)
        vif->ipv6_csum = !!xenbus_read_unsigned(dev->otherend,
                                                "feature-ipv6-csum-offload", 0);
 
+       read_xenbus_frontend_xdp(be, dev);
+
        return 0;
 }
 
@@ -1036,6 +1061,15 @@ static int netback_probe(struct xenbus_device *dev,
                        goto abort_transaction;
                }
 
+               /* we can adjust a headroom for netfront XDP processing */
+               err = xenbus_printf(xbt, dev->nodename,
+                                   "feature-xdp-headroom", "%d",
+                                   provides_xdp_headroom);
+               if (err) {
+                       message = "writing feature-xdp-headroom";
+                       goto abort_transaction;
+               }
+
                /* We don't support rx-flip path (except old guests who
                 * don't grok this feature flag).
                 */