[dpdk-stable] [PATCH 2/3] common/sfc_efx/base: fix MAE match spec class comparison API

[Ivan Malov <ivan.malov@oktetlabs.ru>]

The helper exits once it encounters a field which hasn't its
capability status reported by the FW. Handle the corner case
when the two mask-value pairs match for the field, which, in
the absence of capability information, is sufficient to deem
the class unaffected by the field. Explain this in a comment.

Fixes: bb71f7e0a35a ("common/sfc_efx/base: add match specs class comparison API")
Cc: stable@dpdk.org

Reviewed-by: Andy Moreton <amoreton@xilinx.com>
Reviewed-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
Signed-off-by: Ivan Malov <ivan.malov@oktetlabs.ru>
---
 drivers/common/sfc_efx/base/efx.h     |  5 ++++
 drivers/common/sfc_efx/base/efx_mae.c | 34 +++++++++++++++++----------
 2 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/drivers/common/sfc_efx/base/efx.h b/drivers/common/sfc_efx/base/efx.h
index 3b40e28b4..ccf9c7ab8 100644
--- a/drivers/common/sfc_efx/base/efx.h
+++ b/drivers/common/sfc_efx/base/efx.h
@@ -4283,6 +4283,11 @@ efx_mae_action_set_specs_equal(
  * Conduct a comparison to check whether two match specifications
  * of equal rule type (action / outer) and priority would map to
  * the very same rule class from the firmware's standpoint.
+ *
+ * For match specification fields that are not supported by firmware,
+ * the rule class only matches if the mask/value pairs for that field
+ * are equal. Clients should use efx_mae_match_spec_is_valid() before
+ * calling this API to detect usage of unsupported fields.
  */
 LIBEFX_API
 extern	__checkReturn			efx_rc_t
diff --git a/drivers/common/sfc_efx/base/efx_mae.c b/drivers/common/sfc_efx/base/efx_mae.c
index ef15deb10..c1717d7b0 100644
--- a/drivers/common/sfc_efx/base/efx_mae.c
+++ b/drivers/common/sfc_efx/base/efx_mae.c
@@ -1408,18 +1408,32 @@ efx_mae_match_specs_class_cmp(
 	     ++field_id) {
 		const efx_mae_mv_desc_t *descp = &desc_setp[field_id];
 		efx_mae_field_cap_id_t field_cap_id = descp->emmd_field_cap_id;
-
-		if (descp->emmd_mask_size == 0)
+		const uint8_t *lmaskp = mvpl + descp->emmd_mask_offset;
+		const uint8_t *rmaskp = mvpr + descp->emmd_mask_offset;
+		size_t mask_size = descp->emmd_mask_size;
+		const uint8_t *lvalp = mvpl + descp->emmd_value_offset;
+		const uint8_t *rvalp = mvpr + descp->emmd_value_offset;
+		size_t value_size = descp->emmd_value_size;
+
+		if (mask_size == 0)
 			continue; /* Skip array gap */
 
-		if ((unsigned int)field_cap_id >= field_ncaps)
-			break;
+		if ((unsigned int)field_cap_id >= field_ncaps) {
+			/*
+			 * The FW has not reported capability status for this
+			 * field. It's unknown whether any difference between
+			 * the two masks / values affects the class. The only
+			 * case when the class must be the same is when these
+			 * mask-value pairs match. Otherwise, report mismatch.
+			 */
+			if ((memcmp(lmaskp, rmaskp, mask_size) == 0) &&
+			    (memcmp(lvalp, rvalp, value_size) == 0))
+				continue;
+			else
+				break;
+		}
 
 		if (field_caps[field_cap_id].emfc_mask_affects_class) {
-			const uint8_t *lmaskp = mvpl + descp->emmd_mask_offset;
-			const uint8_t *rmaskp = mvpr + descp->emmd_mask_offset;
-			size_t mask_size = descp->emmd_mask_size;
-
 			if (memcmp(lmaskp, rmaskp, mask_size) != 0) {
 				have_same_class = B_FALSE;
 				break;
@@ -1427,10 +1441,6 @@ efx_mae_match_specs_class_cmp(
 		}
 
 		if (field_caps[field_cap_id].emfc_match_affects_class) {
-			const uint8_t *lvalp = mvpl + descp->emmd_value_offset;
-			const uint8_t *rvalp = mvpr + descp->emmd_value_offset;
-			size_t value_size = descp->emmd_value_size;
-
 			if (memcmp(lvalp, rvalp, value_size) != 0) {
 				have_same_class = B_FALSE;
 				break;
-- 
2.20.1