[PATCH v6 11/25] net/ixgbe: fix ntuple filter priority

[Anatoly Burakov]

Currently, handling of ntuple filter priority is incorrect: it directly
translates values inside the valid range (001b-111b), and clamps all
invalid to 1. This leads to equivalence between rte_flow highest priority
value (0), and rte_flow lower priority values (8+), both of which are
mapped to 1 (lowest priority), while the 1-7 range is reversed (in ntuple,
111b is highest priority, but in rte_flow it is the lowest).

Fix the calculation by

- Translating highest rte_flow priority to highest ntuple priority
- Only clamping low priority values to 1 (lowest priority)
- Reversing the 1-7 mapping to preserve semantic meaning

Fixes: 672be56d76a2 ("net/ixgbe: parse n-tuple filter")
Cc: sta...@dpdk.org

Signed-off-by: Anatoly Burakov <anatoly.bura...@intel.com>
---
 drivers/net/intel/ixgbe/ixgbe_flow.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/drivers/net/intel/ixgbe/ixgbe_flow.c 
b/drivers/net/intel/ixgbe/ixgbe_flow.c
index 76eec33839b..547c6621d3e 100644
--- a/drivers/net/intel/ixgbe/ixgbe_flow.c
+++ b/drivers/net/intel/ixgbe/ixgbe_flow.c
@@ -209,6 +209,7 @@ cons_parse_ntuple_filter(const struct rte_flow_attr *attr,
        const struct rte_flow_item_vlan *vlan_mask;
        struct rte_flow_item_eth eth_null;
        struct rte_flow_item_vlan vlan_null;
+       uint16_t priority;
 
        /* Priority must be 16-bit */
        if (attr->priority > UINT16_MAX) {
@@ -503,9 +504,21 @@ cons_parse_ntuple_filter(const struct rte_flow_attr *attr,
 
        filter->queue = q_act->index;
 
-       filter->priority = (uint16_t)attr->priority;
-       if (attr->priority < IXGBE_MIN_N_TUPLE_PRIO || attr->priority > 
IXGBE_MAX_N_TUPLE_PRIO)
-               filter->priority = 1;
+       /*
+        * rte_flow priority: 0 through UINT32_MAX, 0 is highest
+        *
+        * ntuple priority: 001b through 111b, 111b is highest
+        *
+        * which means we need to transform priority from rte_flow to ntuple:
+        *
+        * 1) clamp max value
+        * 2) reverse
+        * 3) add min value
+        */
+       priority = RTE_MIN(IXGBE_MAX_N_TUPLE_PRIO - 1, 
(uint16_t)attr->priority);
+       priority = IXGBE_MAX_N_TUPLE_PRIO - 1 - priority;
+       priority += IXGBE_MIN_N_TUPLE_PRIO;
+       filter->priority = priority;
 
        return 0;
 }
-- 
2.52.0