RDMA/cxgb3: Support peer-2-peer connection setup

Open MPI, Intel MPI and other applications don't respect the iWARP
requirement that the client (active) side of the connection send the
first RDMA message.  This class of application connection setup is
called peer-to-peer.  Typically once the connection is setup, _both_
sides want to send data.

This patch enables supporting peer-to-peer over the chelsio RNIC by
enforcing this iWARP requirement in the driver itself as part of RDMA
connection setup.

Connection setup is extended, when the peer2peer module option is 1,
such that the MPA initiator will send a 0B Read (the RTR) just after
connection setup.  The MPA responder will suspend SQ processing until
the RTR message is received and reply-to.

In the longer term, this will be handled in a standardized way by
enhancing the MPA negotiation so peers can indicate whether they
want/need the RTR and what type of RTR (0B read, 0B write, or 0B send)
should be sent.  This will be done by standardizing a few bits of the
private data in order to negotiate all this.  However this patch
enables peer-to-peer applications now and allows most of the required
firmware and driver changes to be done and tested now.

Design:

 - Add a module option, peer2peer, to enable this mode.

 - New firmware support for peer-to-peer mode:

	- a new bit in the rdma_init WR to tell it to do peer-2-peer
	  and what form of RTR message to send or expect.

	- process _all_ preposted recvs before moving the connection
	  into rdma mode.

	- passive side: defer completing the rdma_init WR until all
	  pre-posted recvs are processed.  Suspend SQ processing until
	  the RTR is received.

	- active side: expect and process the 0B read WR on offload TX
	  queue. Defer completing the rdma_init WR until all
	  pre-posted recvs are processed.  Suspend SQ processing until
	  the 0B read WR is processed from the offload TX queue.

 - If peer2peer is set, driver posts 0B read request on offload TX
   queue just after posting the rdma_init WR to the offload TX queue.

 - Add CQ poll logic to ignore unsolicitied read responses.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 17 insertions, 4 deletions

diff --git a/drivers/infiniband/hw/cxgb3/cxio_wr.h b/drivers/infiniband/hw/cxgb3/cxio_wr.h
index 969d4d928455..f1a25a821a45 100644
--- a/drivers/infiniband/hw/cxgb3/cxio_wr.h
+++ b/drivers/infiniband/hw/cxgb3/cxio_wr.h
@@ -278,6 +278,17 @@ enum t3_qp_caps {
 	uP_RI_QP_STAG0_ENABLE = 0x10
 } __attribute__ ((packed));
 
+enum rdma_init_rtr_types {
+	RTR_READ = 1,
+	RTR_WRITE = 2,
+	RTR_SEND = 3,
+};
+
+#define S_RTR_TYPE	2
+#define M_RTR_TYPE	0x3
+#define V_RTR_TYPE(x)	((x) << S_RTR_TYPE)
+#define G_RTR_TYPE(x)	((((x) >> S_RTR_TYPE)) & M_RTR_TYPE)
+
 struct t3_rdma_init_attr {
 	u32 tid;
 	u32 qpid;
@@ -293,7 +304,9 @@ struct t3_rdma_init_attr {
 	u32 ird;
 	u64 qp_dma_addr;
 	u32 qp_dma_size;
-	u32 flags;
+	enum rdma_init_rtr_types rtr_type;
+	u16 flags;
+	u16 rqe_count;
 	u32 irs;
 };
 
@@ -309,8 +322,8 @@ struct t3_rdma_init_wr {
 	u8 mpaattrs;		/* 5 */
 	u8 qpcaps;
 	__be16 ulpdu_size;
-	__be32 flags;		/* bits 31-1 - reservered */
-				/* bit     0 - set if RECV posted */
+	__be16 flags_rtr_type;
+	__be16 rqe_count;
 	__be32 ord;		/* 6 */
 	__be32 ird;
 	__be64 qp_dma_addr;	/* 7 */
@@ -324,7 +337,7 @@ struct t3_genbit {
 };
 
 enum rdma_init_wr_flags {
-	RECVS_POSTED = (1<<0),
+	MPA_INITIATOR = (1<<0),
 	PRIV_QP = (1<<1),
 };