IB/hfi1: Fix the allocation of RSM table

The receive side mapping (RSM) on hfi1 hardware is a special
matching mechanism to direct an incoming packet to a given
hardware receive context. It has 4 instances of matching capabilities
(RSM0 - RSM3) that share the same RSM table (RMT). The RMT has a total of
256 entries, each of which points to a receive context.

Currently, three instances of RSM have been used:
1. RSM0 by QOS;
2. RSM1 by PSM FECN;
3. RSM2 by VNIC.

Each RSM instance should reserve enough entries in RMT to function
properly. Since both PSM and VNIC could allocate any receive context
between dd->first_dyn_alloc_ctxt and dd->num_rcv_contexts, PSM FECN must
reserve enough RMT entries to cover the entire receive context index
range (dd->num_rcv_contexts - dd->first_dyn_alloc_ctxt) instead of only
the user receive contexts allocated for PSM
(dd->num_user_contexts). Consequently, the sizing of
dd->num_user_contexts in set_up_context_variables is incorrect.

Fixes: 2280740f ("IB/hfi1: Virtual Network Interface Controller (VNIC) HW support")
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Signed-off-by: Kaike Wan <kaike.wan@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/hfi1/chip.c

@@ -13232,7 +13232,7 @@ static int set_up_context_variables(struct hfi1_devdata *dd)
 	int total_contexts;
 	int ret;
 	unsigned ngroups;
-	int qos_rmt_count;
+	int rmt_count;
 	int user_rmt_reduced;
 	u32 n_usr_ctxts;
 	u32 send_contexts = chip_send_contexts(dd);
@@ -13294,10 +13294,20 @@ static int set_up_context_variables(struct hfi1_devdata *dd)
 		n_usr_ctxts = rcv_contexts - total_contexts;
 	}
 
-	/* each user context requires an entry in the RMT */
-	qos_rmt_count = qos_rmt_entries(dd, NULL, NULL);
-	if (qos_rmt_count + n_usr_ctxts > NUM_MAP_ENTRIES) {
-		user_rmt_reduced = NUM_MAP_ENTRIES - qos_rmt_count;
+	/*
+	 * The RMT entries are currently allocated as shown below:
+	 * 1. QOS (0 to 128 entries);
+	 * 2. FECN for PSM (num_user_contexts + num_vnic_contexts);
+	 * 3. VNIC (num_vnic_contexts).
+	 * It should be noted that PSM FECN oversubscribe num_vnic_contexts
+	 * entries of RMT because both VNIC and PSM could allocate any receive
+	 * context between dd->first_dyn_alloc_text and dd->num_rcv_contexts,
+	 * and PSM FECN must reserve an RMT entry for each possible PSM receive
+	 * context.
+	 */
+	rmt_count = qos_rmt_entries(dd, NULL, NULL) + (num_vnic_contexts * 2);
+	if (rmt_count + n_usr_ctxts > NUM_MAP_ENTRIES) {
+		user_rmt_reduced = NUM_MAP_ENTRIES - rmt_count;
 		dd_dev_err(dd,
 			   "RMT size is reducing the number of user receive contexts from %u to %d\n",
 			   n_usr_ctxts,
@@ -14285,9 +14295,11 @@ static void init_user_fecn_handling(struct hfi1_devdata *dd,
 	u64 reg;
 	int i, idx, regoff, regidx;
 	u8 offset;
+	u32 total_cnt;
 
 	/* there needs to be enough room in the map table */
-	if (rmt->used + dd->num_user_contexts >= NUM_MAP_ENTRIES) {
+	total_cnt = dd->num_rcv_contexts - dd->first_dyn_alloc_ctxt;
+	if (rmt->used + total_cnt >= NUM_MAP_ENTRIES) {
 		dd_dev_err(dd, "User FECN handling disabled - too many user contexts allocated\n");
 		return;
 	}
@@ -14341,7 +14353,7 @@ static void init_user_fecn_handling(struct hfi1_devdata *dd,
 	/* add rule 1 */
 	add_rsm_rule(dd, RSM_INS_FECN, &rrd);
 
-	rmt->used += dd->num_user_contexts;
+	rmt->used += total_cnt;
 }
 
 /* Initialize RSM for VNIC */