On Thu, 23 Apr 2020 at 11:29, Horatiu Vultur
[off-list ref] wrote:

The 04/23/2020 00:26, Vladimir Oltean wrote:

quoted

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Hi Horatiu,

On Fri, 31 May 2019 at 10:18, Horatiu Vultur
[off-list ref] wrote:

quoted

Add ACL support using the TCAM. Using ACL it is possible to create rules
in hardware to filter/redirect frames.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
---

[...]

quoted

quoted

+
+/* Calculate offsets for entry */
+static void is2_data_get(struct vcap_data *data, int ix)
+{
+       u32 i, col, offset, count, cnt, base, width = vcap_is2.tg_width;
+
+       count = (data->tg_sw == VCAP_TG_HALF ? 2 : 4);
+       col = (ix % 2);
+       cnt = (vcap_is2.sw_count / count);
+       base = (vcap_is2.sw_count - col * cnt - cnt);
+       data->tg_value = 0;
+       data->tg_mask = 0;
+       for (i = 0; i < cnt; i++) {
+               offset = ((base + i) * width);
+               data->tg_value |= (data->tg_sw << offset);
+               data->tg_mask |= GENMASK(offset + width - 1, offset);
+       }
+
+       /* Calculate key/action/counter offsets */
+       col = (count - col - 1);
+       data->key_offset = (base * vcap_is2.entry_width) / vcap_is2.sw_count;
+       data->counter_offset = (cnt * col * vcap_is2.counter_width);
+       i = data->type;
+       width = vcap_is2.action_table[i].width;
+       cnt = vcap_is2.action_table[i].count;
+       data->action_offset =
+               (((cnt * col * width) / count) + vcap_is2.action_type_width);
+}
+

[...]

quoted

quoted

+}
+
+static void is2_entry_set(struct ocelot *ocelot, int ix,
+                         struct ocelot_ace_rule *ace)
+{
+       u32 val, msk, type, type_mask = 0xf, i, count;
+       struct ocelot_ace_vlan *tag = &ace->vlan;
+       struct ocelot_vcap_u64 payload = { 0 };
+       struct vcap_data data = { 0 };
+       int row = (ix / 2);
+
+       /* Read row */
+       vcap_row_cmd(ocelot, row, VCAP_CMD_READ, VCAP_SEL_ALL);
+       vcap_cache2entry(ocelot, &data);
+       vcap_cache2action(ocelot, &data);
+
+       data.tg_sw = VCAP_TG_HALF;
+       is2_data_get(&data, ix);
+       data.tg = (data.tg & ~data.tg_mask);
+       if (ace->prio != 0)
+               data.tg |= data.tg_value;

Hi Vladimir,

quoted

This complicated piece of logic here populates the type-group for
subwords > 0 unconditionally, and the type-group for subword 0 only if
the ACE is enabled.

tc filter add dev swp0 ingress protocol ip flower skip_sw src_ip
192.168.1.1 action drop
[   34.172068] is2_entry_set: ace->prio 49152 data tg 0xaa
tc filter del dev swp0 ingress pref 49152
[   44.266662] is2_entry_set: ace->prio 0 data tg 0xa0

What is the purpose of this? Why can't the entire data->tg be set to
zero when deleting it?

I don't remember exactly but let me try:

In case you have only one entry per row, then you could set the tg to
have value 0. But in case you have 2 entries(use half keys), you need to
set the tg to 0 only to the half entry that you delete.

So for example if you have only 1 half entry at subword 1 then the tg
should be 0xa0. Then when you add a new entry on the same row but at
subword 0 then the tg should have the value 0xaa.
The value 0xaa, comes from the fact that the type group for half entry
is 0x2 and this needs to be set for each subword. And IS2 has 4 subwords
therefore 0b10101010 = 0xaa.

I hope this helps, if not I can look deeper in the code and see exactly.

Oh, right, so for half and quarter keys you need to not affect the
neighbour keys when modifying a row. That's exactly the information I
was looking for, thanks!

quoted

Is there any special meaning to a TCAM entry > with subword zero unused?

[...]

--
/Horatiu

-Vladimir