Re: [PATCH 6/7] vfio: Accpet device file from vfio PCI hot reset path

[Jason Gunthorpe <jgg@nvidia.com>]

On Thu, Mar 23, 2023 at 10:14:31AM +0000, Liu, Yi L wrote:
> > From: Jason Gunthorpe <jgg@nvidia.com>
> > Sent: Tuesday, March 21, 2023 3:08 AM
> > 
> > On Thu, Mar 16, 2023 at 05:41:55AM -0700, Yi Liu wrote:
> > > This extends both vfio_file_is_valid() and vfio_file_has_dev() to accept
> > > device file from the vfio PCI hot reset.
> > >
> > > Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> > > ---
> > >  drivers/vfio/vfio_main.c | 23 +++++++++++++++++++----
> > >  1 file changed, 19 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
> > > index fe7446805afd..ebbb6b91a498 100644
> > > --- a/drivers/vfio/vfio_main.c
> > > +++ b/drivers/vfio/vfio_main.c
> > > @@ -1154,13 +1154,23 @@ const struct file_operations vfio_device_fops
> > = {
> > >  	.mmap		= vfio_device_fops_mmap,
> > >  };
> > >
> > > +static struct vfio_device *vfio_device_from_file(struct file *file)
> > > +{
> > > +	struct vfio_device *device = file->private_data;
> > 
> > Isn't this a df now?
> 
> Not yet. It is placed before the cdev series. So it is vfio_device here.
> 
> > > +	if (file->f_op != &vfio_device_fops)
> > > +		return NULL;
> > > +	return device;
> > > +}
> > 
> > The device has to be bound to be a security proof.
> 
> I think it is because this helper is used by vfio_file_has_dev(). This
> requires to be bound to security proof. For now, the device fd is
> got via group. So as long s user can get it, it should have been bound.
> 
> In the later cdev series, the below helper is added to ensure
> given device file has bound to security proof (a.k.a access_granted).

Yes OK that makes senese

Jason