IB/core: Add cross-channel support

The cross-channel feature allows to execute WQEs that involve
synchronization of I/O operations’ on different QPs.

This capability enables to program complex flows with a single
function call, hereby significantly reducing overhead associated
with I/O processing.

Cross-channel operations support is indicated by HCA capability
information.

The queue pairs can be configured to work as a “sync master queue”
or “sync slave queues”.

The added flags are:

1. Device capability flag IB_DEVICE_CROSS_CHANNEL for the
   devices that can perform cross-channel operations.

2. CQ property flag IB_CQ_FLAGS_IGNORE_OVERRUN to disable CQ overrun
   check. This check is useless in cross-channel scenario.

3. QP property flags to indicate if queues are slave or master:
   * IB_QP_CREATE_MANAGED_SEND indicates that posted send work requests
     will not be executed immediately and requires enabling.
   * IB_QP_CREATE_MANAGED_RECV indicates that posted receive work
     requests will not be executed immediately and requires enabling.
   * IB_QP_CREATE_CROSS_CHANNEL declares the QP to work in cross-channel
     mode. If IB_QP_CREATE_MANAGED_SEND and IB_QP_CREATE_MANAGED_RECV are
     not provided, this QP will be sync master queue, else it will be sync
     slave.

Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/core/uverbs_cmd.c

@@ -1824,7 +1824,10 @@ static int create_qp(struct ib_uverbs_file *file,
 		      sizeof(cmd->create_flags))
 		attr.create_flags = cmd->create_flags;
 
-	if (attr.create_flags & ~IB_QP_CREATE_BLOCK_MULTICAST_LOOPBACK) {
+	if (attr.create_flags & ~(IB_QP_CREATE_BLOCK_MULTICAST_LOOPBACK |
+				IB_QP_CREATE_CROSS_CHANNEL |
+				IB_QP_CREATE_MANAGED_SEND |
+				IB_QP_CREATE_MANAGED_RECV)) {
 		ret = -EINVAL;
 		goto err_put;
 	}

include/rdma/ib_verbs.h

@@ -201,6 +201,13 @@ enum ib_device_cap_flags {
 	IB_DEVICE_MEM_WINDOW_TYPE_2B		= (1 << 24),
 	IB_DEVICE_RC_IP_CSUM			= (1 << 25),
 	IB_DEVICE_RAW_IP_CSUM			= (1 << 26),
+	/*
+	 * Devices should set IB_DEVICE_CROSS_CHANNEL if they
+	 * support execution of WQEs that involve synchronization
+	 * of I/O operations with single completion queue managed
+	 * by hardware.
+	 */
+	IB_DEVICE_CROSS_CHANNEL		= (1 << 27),
 	IB_DEVICE_MANAGED_FLOW_STEERING		= (1 << 29),
 	IB_DEVICE_SIGNATURE_HANDOVER		= (1 << 30),
 	IB_DEVICE_ON_DEMAND_PAGING		= (1 << 31),
@@ -246,6 +253,7 @@ struct ib_odp_caps {
 
 enum ib_cq_creation_flags {
 	IB_CQ_FLAGS_TIMESTAMP_COMPLETION   = 1 << 0,
+	IB_CQ_FLAGS_IGNORE_OVERRUN	   = 1 << 1,
 };
 
 struct ib_cq_init_attr {
@@ -950,6 +958,9 @@ enum ib_qp_type {
 enum ib_qp_create_flags {
 	IB_QP_CREATE_IPOIB_UD_LSO		= 1 << 0,
 	IB_QP_CREATE_BLOCK_MULTICAST_LOOPBACK	= 1 << 1,
+	IB_QP_CREATE_CROSS_CHANNEL              = 1 << 2,
+	IB_QP_CREATE_MANAGED_SEND               = 1 << 3,
+	IB_QP_CREATE_MANAGED_RECV               = 1 << 4,
 	IB_QP_CREATE_NETIF_QP			= 1 << 5,
 	IB_QP_CREATE_SIGNATURE_EN		= 1 << 6,
 	IB_QP_CREATE_USE_GFP_NOIO		= 1 << 7,