ice: Optimize switch recipe creation

Currently when creating switch recipes, switch ID is always added as the
first word in every recipe. There are only 5 words in a recipe, so one
word is always wasted. This is also true for the last recipe, which stores
result indexes (in case of chain recipes). Therefore the maximum usable
length of a chain recipe is 4 * 4 = 16 words. 4 words in a recipe, 4
recipes that can be chained (using a 5th one for result indexes).

Current max size chained recipe:
0: smmmm
1: smmmm
2: smmmm
3: smmmm
4: srrrr

Where:
s - switch ID
m - regular match (e.g. ipv4 src addr, udp dst port, etc.)
r - result index

Switch ID does not actually need to be present in every recipe, only in one
of them (in case of chained recipe). This frees up to 8 extra words:
3 from recipes in the middle (because first recipe still needs to have
switch ID), and 5 from one extra recipe (because now the last recipe also
does not have switch ID, so it can chain 1 more recipe).

Max size chained recipe after changes:
0: smmmm
1: Mmmmm
2: Mmmmm
3: Mmmmm
4: MMMMM
5: Rrrrr

Extra usable words available after this change are highlighted with capital
letters.

Changing how switch ID is added is not straightforward, because it's not a
regular lookup. Its FV index and mask can't be determined based on protocol
+ offset pair read from package and instead need to be added manually.

Additionally, change how result indexes are added. Currently they are
always inserted in a new recipe at the end. Example for 13 words, (with
above optimization, switch ID being one of the words):
0: smmmm
1: mmmmm
2: mmmxx
3: rrrxx

Where:
x - unused word

In this and some other cases, the result indexes can be moved just after
last matches because there are unused words, saving one recipe. Example
for 13 words after both optimizations:
0: smmmm
1: mmmmm
2: mmmrr

Note how one less result index is needed in this case, because the last
recipe does not need to "link" to itself.

There are cases when adding an additional recipe for result indexes cannot
be avoided. In that cases result indexes are all put in the last recipe.
Example for 14 words after both optimizations:
0: smmmm
1: mmmmm
2: mmmmx
3: rrrxx

With these two changes, recipes/rules are more space efficient, allowing
more to be created in total.

Co-developed-by: Michal Swiatkowski <[email protected]>
Signed-off-by: Michal Swiatkowski <[email protected]>
Reviewed-by: Przemek Kitszel <[email protected]>
Signed-off-by: Marcin Szycik <[email protected]>
Tested-by: Sujai Buvaneswaran <[email protected]>
Signed-off-by: Tony Nguyen <[email protected]>

Author: Marcin Szycik

drivers/net/ethernet/intel/ice/ice_protocol_type.h

@@ -7,18 +7,24 @@
 
 /* Each recipe can match up to 5 different fields. Fields to match can be meta-
  * data, values extracted from packet headers, or results from other recipes.
- * One of the 5 fields is reserved for matching the switch ID. So, up to 4
- * recipes can provide intermediate results to another one through chaining,
- * e.g. recipes 0, 1, 2, and 3 can provide intermediate results to recipe 4.
+ * Therefore, up to 5 recipes can provide intermediate results to another one
+ * through chaining, e.g. recipes 0, 1, 2, 3 and 4 can provide intermediate
+ * results to recipe 5. Note that one of the fields in one of the recipes must
+ * always be reserved for matching the switch ID.
  */
-#define ICE_NUM_WORDS_RECIPE 4
+#define ICE_NUM_WORDS_RECIPE 5
 
-/* Max recipes that can be chained */
+/* Max recipes that can be chained, not including the last one, which combines
+ * intermediate results.
+ */
 #define ICE_MAX_CHAIN_RECIPE 5
 
-/* 1 word reserved for switch ID from allowed 5 words.
- * So a recipe can have max 4 words. And you can chain 5 such recipes
- * together. So maximum words that can be programmed for look up is 5 * 4.
+/* Total max recipes in chain recipe (including intermediate results) */
+#define ICE_MAX_CHAIN_RECIPE_RES (ICE_MAX_CHAIN_RECIPE + 1)
+
+/* A recipe can have max 5 words, and 5 recipes can be chained together (using
+ * the 6th one, which would contain only result indexes). So maximum words that
+ * can be programmed for lookup is 5 * 5 (not including intermediate results).
  */
 #define ICE_MAX_CHAIN_WORDS (ICE_NUM_WORDS_RECIPE * ICE_MAX_CHAIN_RECIPE)