netdev - Re: [PATCH iwl-next v3 13/13] vfio/ice: Implement vfio

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Message-ID: <20231013140744.GT3952@nvidia.com>
Date: Fri, 13 Oct 2023 11:07:44 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: "Tian, Kevin" <kevin.tian@...el.com>
Cc: "Cao, Yahui" <yahui.cao@...el.com>,
	"intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"Liu, Lingyu" <lingyu.liu@...el.com>,
	"Chittim, Madhu" <madhu.chittim@...el.com>,
	"Samudrala, Sridhar" <sridhar.samudrala@...el.com>,
	"alex.williamson@...hat.com" <alex.williamson@...hat.com>,
	"yishaih@...dia.com" <yishaih@...dia.com>,
	"shameerali.kolothum.thodi@...wei.com" <shameerali.kolothum.thodi@...wei.com>,
	"brett.creeley@....com" <brett.creeley@....com>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"edumazet@...gle.com" <edumazet@...gle.com>,
	"kuba@...nel.org" <kuba@...nel.org>,
	"pabeni@...hat.com" <pabeni@...hat.com>,
	"Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
	"Nguyen, Anthony L" <anthony.l.nguyen@...el.com>
Subject: Re: [PATCH iwl-next v3 13/13] vfio/ice: Implement vfio_pci driver
 for E800 devices

On Fri, Oct 13, 2023 at 08:52:07AM +0000, Tian, Kevin wrote:
> > From: Cao, Yahui <yahui.cao@...el.com>
> > Sent: Monday, September 18, 2023 2:26 PM
> >
> > +static struct file *
> > +ice_vfio_pci_step_device_state_locked(struct ice_vfio_pci_core_device
> > *ice_vdev,
> > +				      u32 new, u32 final)
> > +{
> > +	u32 cur = ice_vdev->mig_state;
> > +	int ret;
> > +
> > +	if (cur == VFIO_DEVICE_STATE_RUNNING && new ==
> > VFIO_DEVICE_STATE_RUNNING_P2P) {
> > +		ice_migration_suspend_dev(ice_vdev->pf, ice_vdev->vf_id);
> > +		return NULL;
> > +	}
> > +
> > +	if (cur == VFIO_DEVICE_STATE_RUNNING_P2P && new ==
> > VFIO_DEVICE_STATE_STOP)
> > +		return NULL;
> > +
> 
> Jason, above is one open which your clarification is appreciated.
> 
> From my talk with Yahui this device can drain/stop outgoing
> traffic but has no interface to stop incoming request.

> is it OK to do nothing for RUNNING_P2P->STOP transition like above?

Yes.

The purpose of RUNNING_P2P->STOP is to allow the device to do anything
it may need to stop internal autonomous operations prior to doing a
get_state. If the device does not have such a concept then a NOP is
fine.

Jason