IB/ehca: Add "port connection autodetect mode"

This patch enhances ehca with a capability to "autodetect" the ports
being connected physically. In order to utilize that function the
module option nr_ports must be set to -1 (default is 2 - two
ports). This feature is experimental and will made the default later.

More detail:

If the user connects only one port to the switch, current code requires
  1) port one to be connected and
  2) module option nr_ports=1 to be given.

If autodetect is enabled, ehca will not wait at creation of the GSI QP
for the respective port to become active. Since firmware does not
accept modify_qp() while the port is down at initialization, we need
to cache all calls to modify_qp() for the SMI/GSI QP and just return a
good return code.

When a port is activated and we get a PORT_ACTIVE event, we replay the
cached modify-qp() parms and re-trigger any posted recv WRs. Only then
do we forward the PORT_ACTIVE event to registered clients.

The result of this autodetect patch is that all ports will be
accessible by the users. Depending on their respective cabling only
those ports that are connected properly will become operable. If a
user tries to modify a regular QP of a non-connected port, modify_qp()
will fail. Furthermore, ibv_devinfo should show the port state
accordingly.

Note that this patch primarily improves the loading behaviour of
ehca. If the cable is removed while the driver is operating and
plugged in again, firmware will handle that properly by sending an
appropriate async event.

Signed-off-by: Hoang-Nam Nguyen <hnguyen@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/drivers/infiniband/hw/ehca/ehca_classes.h b/drivers/infiniband/hw/ehca/ehca_classes.h
index 936580d86ad3..2502366e845f 100644
--- a/drivers/infiniband/hw/ehca/ehca_classes.h
+++ b/drivers/infiniband/hw/ehca/ehca_classes.h
@@ -95,6 +95,10 @@ struct ehca_sma_attr {
 struct ehca_sport {
         struct ib_cq *ibcq_aqp1;
         struct ib_qp *ibqp_sqp[2];
+        /* lock to serialze modify_qp() calls for sqp in normal
+         * and irq path (when event PORT_ACTIVE is received first time)
+         */
+        spinlock_t mod_sqp_lock;
         enum ib_port_state port_state;
         struct ehca_sma_attr saved_attr;
 };
@@ -141,6 +145,14 @@ enum ehca_ext_qp_type {
         EQPT_SRQ       = 3,
 };
 
+/* struct to cache modify_qp()'s parms for GSI/SMI qp */
+struct ehca_mod_qp_parm {
+        int mask;
+        struct ib_qp_attr attr;
+};
+
+#define EHCA_MOD_QP_PARM_MAX 4
+
 struct ehca_qp {
         union {
                 struct ib_qp ib_qp;
@@ -164,6 +176,9 @@ struct ehca_qp {
         struct ehca_cq *recv_cq;
         unsigned int sqerr_purgeflag;
         struct hlist_node list_entries;
+        /* array to cache modify_qp()'s parms for GSI/SMI qp */
+        struct ehca_mod_qp_parm *mod_qp_parm;
+        int mod_qp_parm_idx;
         /* mmap counter for resources mapped into user space */
         u32 mm_count_squeue;
         u32 mm_count_rqueue;
@@ -323,6 +338,7 @@ extern int ehca_port_act_time;
 extern int ehca_use_hp_mr;
 extern int ehca_scaling_code;
 extern int ehca_lock_hcalls;
+extern int ehca_nr_ports;
 
 struct ipzu_queue_resp {
         u32 qe_size;      /* queue entry size */