Re: [dpdk-dev] [PATCH] net/i40e: force promiscuous state after VF reset

["Zhang, Xiao" <xiao.zhang@intel.com>]

Hi Eelco

> -----Original Message-----
> From: Eelco Chaudron [mailto:echaudro@redhat.com]
> Sent: Friday, November 1, 2019 4:13 PM
> To: Xing, Beilei <beilei.xing@intel.com>; Zhang, Xiao <xiao.zhang@intel.com>
> Cc: Zhang, Qi Z <qi.z.zhang@intel.com>; dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] net/i40e: force promiscuous state after VF
> reset
> 
> 
> 
> On 1 Nov 2019, at 3:38, Xing, Beilei wrote:
> 
> >> -----Original Message-----
> >> From: Eelco Chaudron [mailto:echaudro@redhat.com]
> >> Sent: Tuesday, October 29, 2019 3:47 PM
> >> To: Zhang, Xiao <xiao.zhang@intel.com>; Xing, Beilei
> >> <beilei.xing@intel.com>
> >> Cc: Zhang, Qi Z <qi.z.zhang@intel.com>; dev@dpdk.org
> >> Subject: Re: [dpdk-dev] [PATCH] net/i40e: force promiscuous state
> >> after VF reset
> >>
> >>
> >>
> >> On 29 Oct 2019, at 8:39, Zhang, Xiao wrote:
> >>
> >>>> -----Original Message-----
> >>>> From: Eelco Chaudron <echaudro@redhat.com>
> >>>> Sent: Friday, October 25, 2019 5:24 PM
> >>>> To: Xing, Beilei <beilei.xing@intel.com>; Zhang, Xiao
> >>>> <xiao.zhang@intel.com>
> >>>> Cc: Zhang, Qi Z <qi.z.zhang@intel.com>; dev@dpdk.org
> >>>> Subject: Re: [dpdk-dev] [PATCH] net/i40e: force promiscuous state
> >>>> after VF reset
> >>>>
> >>>>
> >>>>
> >>>> On 17 Oct 2019, at 8:34, Xing, Beilei wrote:
> >>>>
> >>>>>> On 17 Sep 2019, at 9:40, Eelco Chaudron wrote:
> >>>>>>
> >>>>>>> Even though the device reset is successful, disabling
> >>>>>>> promiscuous
> >>>>>>> mode might not always succeed, causing enabling it after reset
> >>>>>>> to
> >>>>>>> fail.
> >>>>>>> This would happen when the kernel driver requires a reset of the
> >>>>>>> VF.
> >>>>>>>
> >>>>>>> This patch resets the internal state, so next time promiscuous
> >>>>>>> mode
> >>>>>>> is configured it will be enabled.
> >>>>>>>
> >>>>>>> Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
> >>>>>>> ---
> >>>>>>>  drivers/net/i40e/i40e_ethdev_vf.c | 10 ++++++++++
> >>>>>>>  1 file changed, 10 insertions(+)
> >>>>>>>
> >>>>>>> diff --git a/drivers/net/i40e/i40e_ethdev_vf.c
> >>>>>>> b/drivers/net/i40e/i40e_ethdev_vf.c
> >>>>>>> index 551f6fa..e0f99a4 100644
> >>>>>>> --- a/drivers/net/i40e/i40e_ethdev_vf.c
> >>>>>>> +++ b/drivers/net/i40e/i40e_ethdev_vf.c
> >>>>>>> @@ -2276,11 +2276,21 @@ static int eth_i40evf_pci_remove(struct
> >>>>>>> rte_pci_device *pci_dev)  i40evf_dev_reset(struct rte_eth_dev
> >>>>>>> *dev)
> >>>>>>> {
> >>>>>>>  	int ret;
> >>>>>>> +	struct i40e_vf *vf =
> >>>>>>> I40EVF_DEV_PRIVATE_TO_VF(dev->data->dev_private);
> >>>>>>>
> >>>>>>>  	ret = i40evf_dev_uninit(dev);
> >>>>>>>  	if (ret)
> >>>>>>>  		return ret;
> >>>>>>>
> >>>>>>> +	/*
> >>>>>>> +	 * Even though the device reset is successful disabling
> >>>>>>> promiscuous
> >>>>>>> +	 * mode might not always succeed, causing enabling it after
> >>>>>>> reset
> >>>>>>> to
> >>>>>
> >>>>> I think we need to root cause why fail to disable promiscuous mode
> >>>>> and
> >>>>> try to fix it first.
> >>>>
> >>>> I’ve copied in Xiao who helped me identify the issue in your
> >>>> driver.
> >>>>
> >>>> The issue is because the change from kernel pf was not synced to
> >>>> DPDK
> >>>> vf during
> >>>> the closing period of reset, so we get this failure. Xiao can you
> >>>> add
> >>>> more details?
> >>>>
> >>>
> >>> The root cause is when kernel pf generate DPDK vf reset event, the
> >>> flag
> >>> vf->promisc_unicast_enabled will not be cleared but promiscuous mode
> >>> is
> >>> disabled. When trying to enable promiscuous mode next time by
> >>> calling
> >>> i40evf_dev_promiscuous_enable won't work because it will check the
> >>> vf->promisc_unicast_enabled flag first.
> >>>
> >>> static int
> >>> i40evf_dev_promiscuous_enable(struct rte_eth_dev *dev)
> >>> {
> >>> ...
> >>>     /* If enabled, just return */
> >>>     if (vf->promisc_unicast_enabled)
> >>>         return 0;
> >>> ...
> >>> }
> >>>
> >>> Hi Eelco,
> >>>
> >>> I think you may need add more detailed message in the commit log or
> >>> comments.
> >>
> >> My interpretation of the request was that Beilei wanted to know why
> >> disabling promiscuous mode in HW was failing. Beilei can you comment,
> >> is
> >> the additional description from Xiao enough?
> >
> > Yes, promisc_unicast_enabled flag is not cleared during vf reset
> > because fail to disable promiscuous mode,
> > So I think we need to root cause why fail to  disable promiscuous mode
> > first.
> > This patch looks like a workaround but not a fix.
> >
> 
> This was debugged together with Xiao and from what I understand is that
> DPDK fails to reset promiscuous mode in hardware as PF and VF operations
> are not synced between kernel and DPDK.
> 
> Xiao told me this could not be fixed in another way, Xiao can you
> comment?
> 

Checked again, the root cause is not synced issue between kernel and DPDK during reset.
Suggest to remove the checking and setting of promisc_unicast_enabled flag, since this flag is only used when enable/disable promiscuous mode.
Considering the un-synced issue, it will be more clean if remove the flag.
Also same with flag promisc_multicast_enabled.

> >>
> >>>>
> >>>>>>> +	 * fail. This would happen when the kernel driver requires a
> >>>>>>> reset
> >>>>>>> +	 * of the VF.
> >>>>>>> +	 */
> >>>>>>> +	if (rte_eal_process_type() == RTE_PROC_PRIMARY)
> >>>>>>> +		vf->promisc_unicast_enabled = FALSE;
> >>>>>>> +
> >>>>>>>  	ret = i40evf_dev_init(dev);
> >>>>>>>
> >>>>>>>  	return ret;
> >>>>>>> --
> >>>>>>> 1.8.3.1