IB/core: Handle table with full and partial membership for the same P_Key

Extend the cached and non-cached P_Key table lookups to handle limited
and full membership of the same P_Key to co-exist in the P_Key table.

This is necessary for SR-IOV, to allow for some guests would to have
the full membership P_Key in their virtual P_Key table, while other
guests on the same physical HCA would have the limited one.
To support this, we need both the limited and full membership P_Keys
to be present in the master's (hypervisor physical port) P_Key table.

The algorithm for handling P_Key tables which contain both the limited
and the full membership versions of the same P_Key works as follows:

When scanning the P_Key table for a 15-bit P_Key:

A. If there is a full member version of that P_Key anywhere in the
    table, return its index (even if a limited-member version of the
    P_Key exists earlier in the table).

B. If the full member version is not in the table, but the
   limited-member version is in the table, return the index of the
   limited P_Key.
Signed-off-by: Liran Liss <liranl@mellanox.com>
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/core/cache.c

@@ -167,6 +167,7 @@ int ib_find_cached_pkey(struct ib_device *device,
 	unsigned long flags;
 	int i;
 	int ret = -ENOENT;
+	int partial_ix = -1;
 
 	if (port_num < start_port(device) || port_num > end_port(device))
 		return -EINVAL;
@@ -179,11 +180,19 @@ int ib_find_cached_pkey(struct ib_device *device,
 
 	for (i = 0; i < cache->table_len; ++i)
 		if ((cache->table[i] & 0x7fff) == (pkey & 0x7fff)) {
-			*index = i;
-			ret = 0;
-			break;
+			if (cache->table[i] & 0x8000) {
+				*index = i;
+				ret = 0;
+				break;
+			} else
+				partial_ix = i;
 		}
 
+	if (ret && partial_ix >= 0) {
+		*index = partial_ix;
+		ret = 0;
+	}
+
 	read_unlock_irqrestore(&device->cache.lock, flags);
 
 	return ret;

drivers/infiniband/core/device.c

@@ -707,18 +707,28 @@ int ib_find_pkey(struct ib_device *device,
 {
 	int ret, i;
 	u16 tmp_pkey;
+	int partial_ix = -1;
 
 	for (i = 0; i < device->pkey_tbl_len[port_num - start_port(device)]; ++i) {
 		ret = ib_query_pkey(device, port_num, i, &tmp_pkey);
 		if (ret)
 			return ret;
-
 		if ((pkey & 0x7fff) == (tmp_pkey & 0x7fff)) {
-			*index = i;
-			return 0;
+			/* if there is full-member pkey take it.*/
+			if (tmp_pkey & 0x8000) {
+				*index = i;
+				return 0;
+			}
+			if (partial_ix < 0)
+				partial_ix = i;
 		}
 	}
 
+	/*no full-member, if exists take the limited*/
+	if (partial_ix >= 0) {
+		*index = partial_ix;
+		return 0;
+	}
 	return -ENOENT;
 }
 EXPORT_SYMBOL(ib_find_pkey);