Re: [dpdk-dev] [PATCH] net/ixgbe: clear registers of all queues on VF reset

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 1/5/2021 9:02 AM, Simon Ellmann wrote:
> On 1/4/21 4:56 PM, Ferruh Yigit wrote:
> 
>> On 12/18/2020 2:34 AM, Wang, Haiyue wrote:
>>>> -----Original Message-----
>>>> From: Simon Ellmann <simon.ellmann@tum.de>
>>>> Sent: Friday, December 18, 2020 01:15
>>>> To: Guo, Jia <jia.guo@intel.com>; Wang, Haiyue <haiyue.wang@intel.com>
>>>> Cc: dev@dpdk.org; Simon Ellmann <simon.ellmann@tum.de>
>>>> Subject: [PATCH] net/ixgbe: clear registers of all queues on VF reset
>>>>
>>>> ixgbe devices support up to 8 Rx and Tx queues per virtual function.
>>>> Currently, the registers of only seven queues are set to default when
>>>> resetting a VF.
>>>>
>>>
>>> Fixes: d17d0b7a2407 ("ixgbe/base: reset VF registers")
>>> Cc: stable@dpdk.org
>>>
>>>> Signed-off-by: Simon Ellmann <simon.ellmann@tum.de>
>>>> ---
>>>>   drivers/net/ixgbe/base/ixgbe_vf.c | 2 +-
>>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>
>>> Good catch, thanks!
>>>
>>> Acked-by: Haiyue Wang <haiyue.wang@intel.com>
>>>
>>
>> This seems a very long lived defect, I am just suspicious if there was a 
>> reason to limit queue number to 7.
>>
>>
>> Simon,
>>
>> How did you find the defect? And did you test/verify it with the update? 
>> (assuming you are using all 8 queues for the VF)
> 
> Hi Ferruh,
> 
> I was implementing ixgbevf for ixy.rs (https://ixy.rs/) by reading the code in 
> DPDK and Linux. While doing that I noticed that DPDK was only resetting 7 queues 
> which looked like a off-by-one error to me. I would have expected a comment if 
> this behaviour was intentional. I haven't checked the update.
> 

Most probably you are right, but when I tried to test this, the HW I have 
doesn't let me set more than 4 queues for the VF, so I was a little suspicious 
about hardcoded 8 value.

What do you think using 'hw->mac.max_rx_queues' instead? Which seems used a few 
other places to walk the queues?

Also can you please point the equivalent code in the Linux driver? As far as I 
can see it also uses 'adapter->num_rx_queues', but I wonder if is there any 
hardcoded value there.