RDMA/cma: Add multicast communication support

Extend rdma_cm to support multicast communication.  Multicast support
is added to the existing RDMA_PS_UDP port space, as well as a new
RDMA_PS_IPOIB port space.  The latter port space allows joining the
multicast groups used by IPoIB, which enables offloading IPoIB traffic
to a separate QP.  The port space determines the signature used in the
MGID when joining the group.  The newly added RDMA_PS_IPOIB also
allows for unicast operations, similar to RDMA_PS_UDP.

Supporting the RDMA_PS_IPOIB requires changing how UD QPs are initialized,
since we can no longer assume that the qkey is constant.  This requires
saving the Q_Key to use when attaching to a device, so that it is
available when creating the QP.  The Q_Key information is exported to
the user through the existing rdma_init_qp_attr() interface.

Multicast support is also exported to userspace through the rdma_ucm.

Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/include/rdma/rdma_user_cm.h b/include/rdma/rdma_user_cm.h
index 9572ab8eeac1..f632b0c007c9 100644
--- a/include/rdma/rdma_user_cm.h
+++ b/include/rdma/rdma_user_cm.h
@@ -38,7 +38,7 @@
 #include <rdma/ib_user_verbs.h>
 #include <rdma/ib_user_sa.h>
 
-#define RDMA_USER_CM_ABI_VERSION        3
+#define RDMA_USER_CM_ABI_VERSION        4
 
 #define RDMA_MAX_PRIVATE_DATA           256
 
@@ -58,7 +58,9 @@ enum {
         RDMA_USER_CM_CMD_GET_EVENT,
         RDMA_USER_CM_CMD_GET_OPTION,
         RDMA_USER_CM_CMD_SET_OPTION,
-        RDMA_USER_CM_CMD_NOTIFY
+        RDMA_USER_CM_CMD_NOTIFY,
+        RDMA_USER_CM_CMD_JOIN_MCAST,
+        RDMA_USER_CM_CMD_LEAVE_MCAST
 };
 
 /*
@@ -188,6 +190,13 @@ struct rdma_ucm_notify {
         __u32 event;
 };
 
+struct rdma_ucm_join_mcast {
+        __u64 response;         /* rdma_ucm_create_id_resp */
+        __u64 uid;
+        struct sockaddr_in6 addr;
+        __u32 id;
+};
+
 struct rdma_ucm_get_event {
         __u64 response;
 };