xen-netback: add control protocol implementation

My recent patch to include/xen/interface/io/netif.h defines a new shared
ring (in addition to the rx and tx rings) for passing control messages
from a VM frontend driver to a backend driver.

A previous patch added the necessary boilerplate for mapping the control
ring from the frontend, should it be created. This patch adds
implementations for each of the defined protocol messages.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/xen-netback/Makefile

@@ -1,3 +1,3 @@
 obj-$(CONFIG_XEN_NETDEV_BACKEND) := xen-netback.o
 
-xen-netback-y := netback.o xenbus.o interface.o
+xen-netback-y := netback.o xenbus.o interface.o hash.o

drivers/net/xen-netback/common.h

@@ -220,6 +220,35 @@ struct xenvif_mcast_addr {
 
 #define XEN_NETBK_MCAST_MAX 64
 
+#define XEN_NETBK_MAX_HASH_KEY_SIZE 40
+#define XEN_NETBK_MAX_HASH_MAPPING_SIZE 128
+#define XEN_NETBK_HASH_TAG_SIZE 40
+
+struct xenvif_hash_cache_entry {
+	struct list_head link;
+	struct rcu_head rcu;
+	u8 tag[XEN_NETBK_HASH_TAG_SIZE];
+	unsigned int len;
+	u32 val;
+	int seq;
+};
+
+struct xenvif_hash_cache {
+	spinlock_t lock;
+	struct list_head list;
+	unsigned int count;
+	atomic_t seq;
+};
+
+struct xenvif_hash {
+	unsigned int alg;
+	u32 flags;
+	u8 key[XEN_NETBK_MAX_HASH_KEY_SIZE];
+	u32 mapping[XEN_NETBK_MAX_HASH_MAPPING_SIZE];
+	unsigned int size;
+	struct xenvif_hash_cache cache;
+};
+
 struct xenvif {
 	/* Unique identifier for this interface. */
 	domid_t          domid;
@@ -251,6 +280,8 @@ struct xenvif {
 	unsigned int num_queues; /* active queues, resource allocated */
 	unsigned int stalled_queues;
 
+	struct xenvif_hash hash;
+
 	struct xenbus_watch credit_watch;
 	struct xenbus_watch mcast_ctrl_watch;
 
@@ -353,6 +384,7 @@ extern bool separate_tx_rx_irq;
 extern unsigned int rx_drain_timeout_msecs;
 extern unsigned int rx_stall_timeout_msecs;
 extern unsigned int xenvif_max_queues;
+extern unsigned int xenvif_hash_cache_size;
 
 #ifdef CONFIG_DEBUG_FS
 extern struct dentry *xen_netback_dbg_root;
@@ -366,4 +398,18 @@ void xenvif_skb_zerocopy_complete(struct xenvif_queue *queue);
 bool xenvif_mcast_match(struct xenvif *vif, const u8 *addr);
 void xenvif_mcast_addr_list_free(struct xenvif *vif);
 
+/* Hash */
+void xenvif_init_hash(struct xenvif *vif);
+void xenvif_deinit_hash(struct xenvif *vif);
+
+u32 xenvif_set_hash_alg(struct xenvif *vif, u32 alg);
+u32 xenvif_get_hash_flags(struct xenvif *vif, u32 *flags);
+u32 xenvif_set_hash_flags(struct xenvif *vif, u32 flags);
+u32 xenvif_set_hash_key(struct xenvif *vif, u32 gref, u32 len);
+u32 xenvif_set_hash_mapping_size(struct xenvif *vif, u32 size);
+u32 xenvif_set_hash_mapping(struct xenvif *vif, u32 gref, u32 len,
+			    u32 off);
+
+void xenvif_set_skb_hash(struct xenvif *vif, struct sk_buff *skb);
+
 #endif /* __XEN_NETBACK__COMMON_H__ */