netdev - RE: [Intel-wired-lan] [PATCH iwl-next v3] i40e: add ability to reset vf for tx and rx mdd events

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Message-ID: <SJ0PR11MB586669F98C3D6D4544EA9E32E5932@SJ0PR11MB5866.namprd11.prod.outlook.com>
Date: Tue, 3 Sep 2024 18:13:56 +0000
From: "Loktionov, Aleksandr" <aleksandr.loktionov@...el.com>
To: mschmidt <mschmidt@...hat.com>
CC: "intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>,
	"Nguyen, Anthony L" <anthony.l.nguyen@...el.com>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>, "Sokolowski, Jan" <jan.sokolowski@...el.com>,
	"Connolly, Padraig J" <padraig.j.connolly@...el.com>
Subject: RE: [Intel-wired-lan] [PATCH iwl-next v3] i40e: add ability to reset
 vf for tx and rx mdd events



> -----Original Message-----
> From: Michal Schmidt <mschmidt@...hat.com>
> Sent: Monday, September 2, 2024 3:25 PM
> To: Loktionov, Aleksandr <aleksandr.loktionov@...el.com>
> Cc: intel-wired-lan@...ts.osuosl.org; Nguyen, Anthony L
> <anthony.l.nguyen@...el.com>; netdev@...r.kernel.org; Sokolowski, Jan
> <jan.sokolowski@...el.com>; Connolly, Padraig J
> <padraig.j.connolly@...el.com>
> Subject: Re: [Intel-wired-lan] [PATCH iwl-next v3] i40e: add ability
> to reset vf for tx and rx mdd events
> 
> On Fri, Aug 30, 2024 at 9:28 PM Aleksandr Loktionov
> <aleksandr.loktionov@...el.com> wrote:
> >
> > In cases when vf sends malformed packets that are classified as
> > malicious, sometimes it causes tx queue to freeze. This frozen queue
> > can be stuck for several minutes being unusable. When mdd event
> > occurs, there is a posibility to perform a graceful vf reset to
> > quickly bring vf back to operational state.
> >
> > Currently vf iqueues are being disabled if mdd event occurs.
> > Add the ability to reset vf if tx or rx mdd occurs.
> > Add mdd events logging throttling /* avoid dmesg polution */.
> > Unify tx rx mdd messages formats.
> >
> > Co-developed-by: Jan Sokolowski <jan.sokolowski@...el.com>
> > Signed-off-by: Jan Sokolowski <jan.sokolowski@...el.com>
> > Co-developed-by: Padraig J Connolly <padraig.j.connolly@...el.com>
> > Signed-off-by:  Padraig J Connolly <padraig.j.connolly@...el.com>
> > Signed-off-by: Aleksandr Loktionov <aleksandr.loktionov@...el.com>
> > ---
> 
> Thanks, we need this. ice has the same ability.
> Just one question about the patch:
> 
> [...]
> >  static void i40e_handle_mdd_event(struct i40e_pf *pf)  {
> >         struct i40e_hw *hw = &pf->hw;
> >         bool mdd_detected = false;
> >         struct i40e_vf *vf;
> >         u32 reg;
> >         int i;
> >
> > -       if (!test_bit(__I40E_MDD_EVENT_PENDING, pf->state))
> > +       if (!test_and_clear_bit(__I40E_MDD_EVENT_PENDING, pf-
> >state))
> > + {
> 
> OK, using test_and_clear_bit is good, but ...:
> 
> [...]
> >
> >         /* re-enable mdd interrupt cause */
> >         clear_bit(__I40E_MDD_EVENT_PENDING, pf->state);
> 
> Here the bit is cleared again. Why?
> 
He code with clear_bit() is legacy and >7y old. So I can guess it's to avoid race condition.
This patch introduced new functionality without changing legacy control flow, and has been tested in OOT driver. 
If you have suggestions in control flow change I'd suggest to merge this patch first and then try to refactor.
What do you think?

> >         reg = rd32(hw, I40E_PFINT_ICR0_ENA);
> >         reg |=  I40E_PFINT_ICR0_ENA_MAL_DETECT_MASK;
> >         wr32(hw, I40E_PFINT_ICR0_ENA, reg);
> >         i40e_flush(hw);
> > +
> > +       i40e_print_vfs_mdd_events(pf);
> >  }
> 
> Michal