> -----Original Message-----
> From: Alex Williamson <[email protected]>
> Sent: Friday, March 31, 2023 9:25 PM
> To: Jiang, Yanting <[email protected]>
> Cc: Liu, Yi L <[email protected]>; [email protected]; Tian, Kevin
> <[email protected]>; [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected];
> [email protected]; [email protected]; intel-
> [email protected]; [email protected]; Hao, Xudong
> <[email protected]>; Zhao, Yan Y <[email protected]>; Xu, Terrence
> <[email protected]>
> Subject: Re: [PATCH v2 00/10] Introduce new methods for verifying ownership in
> vfio PCI hot reset
>
> On Fri, 31 Mar 2023 03:14:23 +0000
> "Jiang, Yanting" <[email protected]> wrote:
>
> > >
> > > VFIO_DEVICE_PCI_HOT_RESET requires user to pass an array of group
> > > fds to prove that it owns all devices affected by resetting the
> > > calling device. This series introduces several extensions to allow
> > > the ownership check better aligned with iommufd and coming vfio device
> cdev support.
> > >
> > > First, resetting an unopened device is always safe given nobody is
> > > using it. So relax the check to allow such devices not covered by
> > > group fd array. [1]
> > >
> > > When iommufd is used we can simply verify that all affected devices
> > > are bound to a same iommufd then no need for the user to provide extra fd
> information.
> > > This is enabled by the user passing a zero-length fd array and
> > > moving forward this should be the preferred way for hot reset. [2]
> > >
> > > However the iommufd method has difficulty working with noiommu
> > > devices since those devices don't have a valid iommufd, unless the
> > > noiommu device is in a singleton dev_set hence no ownership check is
> > > required. [3]
> > >
> > > For noiommu backward compatibility a 3rd method is introduced by
> > > allowing the user to pass an array of device fds to prove ownership.
> > > [4]
> > >
> > > As suggested by Jason [5], we have this series to introduce the
> > > above stuffs to the vfio PCI hot reset. Per the dicussion in [6],
> > > this series also adds a new _INFO ioctl to get hot reset scope for given
> device.
> > >
> > Tested NIC passthrough on Intel platform.
> > Result looks good hence,
> > Tested by: Jiang, Yanting <[email protected]>
>
> I'm not aware of any userspace that exercises this reset ioctl in cdev mode.
> Is
> this regression testing only? Thanks,
>
> Alex
Hi Alex,
Yes, only regression testing and some negative testing for NIC passthrough with
legacy vfio mode, vfio iommufd compat mode, and cdev mode.
Thanks,
Yanting
