IB/core: IB cache enhancements to support Infiniband security

Cache the subnet prefix and add a function to access it. Enforcing
security requires frequent queries of the subnet prefix and the pkeys in
the pkey table.
Signed-off-by: Daniel Jurgens <danielj@mellanox.com>
Reviewed-by: Eli Cohen <eli@mellanox.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Acked-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

drivers/infiniband/core/cache.c

@@ -911,6 +911,26 @@ int ib_get_cached_pkey(struct ib_device *device,
 }
 EXPORT_SYMBOL(ib_get_cached_pkey);
 
+int ib_get_cached_subnet_prefix(struct ib_device *device,
+				u8                port_num,
+				u64              *sn_pfx)
+{
+	unsigned long flags;
+	int p;
+
+	if (port_num < rdma_start_port(device) ||
+	    port_num > rdma_end_port(device))
+		return -EINVAL;
+
+	p = port_num - rdma_start_port(device);
+	read_lock_irqsave(&device->cache.lock, flags);
+	*sn_pfx = device->cache.ports[p].subnet_prefix;
+	read_unlock_irqrestore(&device->cache.lock, flags);
+
+	return 0;
+}
+EXPORT_SYMBOL(ib_get_cached_subnet_prefix);
+
 int ib_find_cached_pkey(struct ib_device *device,
 			u8                port_num,
 			u16               pkey,
@@ -1108,6 +1128,8 @@ static void ib_cache_update(struct ib_device *device,
 	device->cache.ports[port - rdma_start_port(device)].port_state =
 		tprops->state;
 
+	device->cache.ports[port - rdma_start_port(device)].subnet_prefix =
+							tprops->subnet_prefix;
 	write_unlock_irq(&device->cache.lock);
 
 	kfree(gid_cache);

drivers/infiniband/core/core_priv.h

@@ -176,4 +176,7 @@ int ib_nl_handle_set_timeout(struct sk_buff *skb,
 int ib_nl_handle_ip_res_resp(struct sk_buff *skb,
 			     struct netlink_callback *cb);
 
+int ib_get_cached_subnet_prefix(struct ib_device *device,
+				u8                port_num,
+				u64              *sn_pfx);
 #endif /* _CORE_PRIV_H */

include/rdma/ib_verbs.h

@@ -1891,6 +1891,7 @@ enum ib_mad_result {
 };
 
 struct ib_port_cache {
+	u64		      subnet_prefix;
 	struct ib_pkey_cache  *pkey;
 	struct ib_gid_table   *gid;
 	u8                     lmc;