RE: [PATCH v2 10/10] vfio/pci: Add VFIO_DEVICE_GET_PCI_HOT_RESET_GROUP_INFO

Tian, Kevin
2023-03-30T01:33:46Z

> From: Tian, Kevin <kevin.tian@intel.com>
> Sent: Thursday, March 30, 2023 9:10 AM
>
> > From: Jason Gunthorpe <jgg@nvidia.com>
> > Sent: Wednesday, March 29, 2023 11:50 PM
> >
> > On Wed, Mar 29, 2023 at 09:41:26AM +0000, Tian, Kevin wrote:
> >
> > > We could extend bind_iommufd to return the group id or introduce a
> > > new ioctl to query it per dev_id.
> >
> > > Once that is in place looks we don't need a new _INFO ioctl?
> >
> > The iommu_group and the reset group are different things
> >
> > The issue is processing the BDF strings, not the group ID.
> >
> > Probably we should have some way for iommufd to report the group_id
> > from the dev_id?
> >
>
> Yes, that is my thought. Though iommu_group and reset group are
> different things we could still leverage existing _INFO ioctl once there
> is a way to associated dev_id to group_id.

Please ignore this comment. Yes they are different things so even if
a dev_id is in a group_id reported on a reset BDF string it doesn't mean
this dev_id is in the reset group.

Qemu can know that all affected devices are either owned by itself or
not used by other processes if dev_id's opened by itself can be
associated to all group_id's reported in the BDF strings. But it still lacks
of information to tell the reset dependency within those opened devices
within Qemu.

So we do need a new _INFO ioctl for cdev. :/