[dpdk-dev] [PATCH v4] app/testpmd: fix the default RSS key configuration

[Ferruh Yigit]

On 10/9/2020 12:55 PM, oulijun wrote:
> 
> 
> 在 2020/9/30 20:57, Ferruh Yigit 写道:
>> On 9/24/2020 2:45 PM, Lijun Ou wrote:
>>> It use the NIC valid default RSS key instead of the testpmd
>>> dummy RSS key in the flow configuration when the RSS key is
>>> not specified in the flow rule. If the NIC RSS key is
>>> invalid, it will use testpmd dummy RSS key as the default
>>> key.
>>
>> Can you please describe the impact, what fails without this fix?
>>
> Hi, Ferruh
>    According to Phil Yang's suggestion, I've put the impact description in the 
> cover letter.
>     When a user runs a flow create cmd to configure an RSS rule
> with specifying the empty rss actions in testpmd, this mean
> that the flow gets the default RSS functions from the valid
> NIC default RSS hash key. However, the testpmd is not set
> the default RSS key incorrectly when RSS key is not specified
> in flow create cmd.
>     After the testpmd is started, run the flow create cmd without specifying the 
> RSS hash key. Ensure that RSS hash key queried after
> the RSS flow is configured is the same as the default key after the
> testpmd is start.
> 
>>>
>>> Fixes: ac8d22de2394 ("ethdev: flatten RSS configuration in flow API")
>>> Cc: stable at dpdk.org
>>>
>>> Signed-off-by: Lijun Ou <oulijun at huawei.com>
>>> ---
>>> V3->V4:
>>> -fix checkpatch warning and shorter commit content.
>>>
>>> V2->V3:
>>> -fix checkpatch warning.
>>>
>>> V1->V2:
>>> -fix the commit.
>>> ---
>>>   app/test-pmd/cmdline_flow.c | 8 ++++++++
>>>   1 file changed, 8 insertions(+)
>>>
>>> diff --git a/app/test-pmd/cmdline_flow.c b/app/test-pmd/cmdline_flow.c
>>> index 6263d30..e6648da 100644
>>> --- a/app/test-pmd/cmdline_flow.c
>>> +++ b/app/test-pmd/cmdline_flow.c
>>> @@ -4312,6 +4312,7 @@ parse_vc_action_rss(struct context *ctx, const struct 
>>> token *token,
>>>           action_rss_data->queue[i] = i;
>>>       if (!port_id_is_invalid(ctx->port, DISABLED_WARN) &&
>>>           ctx->port != (portid_t)RTE_PORT_ALL) {
>>> +        struct rte_eth_rss_conf rss_conf = {0};
>>>           struct rte_eth_dev_info info;
>>>           int ret2;
>>> @@ -4322,6 +4323,13 @@ parse_vc_action_rss(struct context *ctx, const struct 
>>> token *token,
>>>           action_rss_data->conf.key_len =
>>>               RTE_MIN(sizeof(action_rss_data->key),
>>>                   info.hash_key_size);
>>> +
>>> +        rss_conf.rss_key_len = sizeof(action_rss_data->key);
>>> +        rss_conf.rss_key = action_rss_data->key;
>>
>> 'rss_conf.rss_key_len' is the input parameter, it looks like it has been used 
>> as the size of the 'rss_key', but as far as I can see it is not.
>>
> Yes, rss_key_len and rss_key is configured independently. In fact, when the user 
> configures the rss_key， we should know rss_key_len.
>> Because of this if 'info.hash_key_size' is bigger than 
>> 'sizeof(action_rss_data->key)', won't PMD overwrite the stack for the 
>> remaining bytes?
> if info.hash_key_size and action_rss_data->key is set used RSS flow cmd when 
> info.hash_key_size is bigger than sizeof(action_rss_data->key)， the driver will 
> return an error.
 >

How can driver return an error?
Both 'rss_conf.rss_key_len' & 'rss_conf.rss_key' filled by driver, and driver 
expect 'rss_conf.rss_key' is big enough to hold its key.
Here 'rss_conf.rss_key' points to fixed size 'action_rss_data->key' array 
without checking the driver key length.

Where this driver check happens, am I missing it?

>>
>> Can you please check?
>>
>>> +        ret2 = rte_eth_dev_rss_hash_conf_get(ctx->port, &rss_conf);
>>> +        if (ret2 != 0)
>>> +            return ret2;
>>
>> If PMD not implemented the 'rss_hash_conf_get' dev_ops, should it fail the RSS 
>> action?
> Yes, When the RSS hash key is not specified in the RSS flow, ensure that the RSS 
> hash key remains unchanged and is the same as that configured in the hardware 
> when the testpmd is started.

OK, but this means any PMD not implemented dev_ops to get RSS key won't able to 
use rte flow RSS action via testpmd, not sure if this is right.

What this patch does is read the device configured RSS key, and feed it back to 
rte flow RSS action, to be sure device key is not changed.

Instead, can we update the rte flow RSS action to not change the key if it is 
not provided, and don't provide one in the testpmd by default.

What do you think?

>>
>>> +        action_rss_data->conf.key = rss_conf.rss_key;
>>>       }
>>>       action->conf = &action_rss_data->conf;
>>>       return ret;
>>>
>>
>> .
>>