Re: [PATCH] vfio: Set PCI_DEV_FLAGS_ASSIGNED when assigning device to guest

[Alex Williamson <alex.williamson@redhat.com>]

[cc +linux-pci]

On Thu, 2014-01-30 at 10:33 -0700, Alex Williamson wrote:
> On Thu, 2014-01-30 at 22:54 +0530, Bandan Das wrote:
> > Some drivers such as ixgbe rely on pci_vfs_assigned() to prevent
> > disabling sr-iov when vfs are still assigned during hotplug
> > event or module removal. Set and unset PCI_DEV_FLAGS_ASSIGNED
> > appropriately
> 
> This flag has always felt like a band-aide for KVM device assignment
> because a device could be used without an actual driver attached to the
> device.  vfio-pci is an actual driver, so why should it matter whether
> the device is assigned or in use by ixgbevf or in use by pci-vfio?  It
> seems like sr-iov shouldn't be disabled so long as either a driver or
> this (needs to be deprecated) flag are set.  Thanks,
> 
> Alex
> 
> > ---
> >  drivers/vfio/pci/vfio_pci.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> > index 7ba0424..7cc7ed6 100644
> > --- a/drivers/vfio/pci/vfio_pci.c
> > +++ b/drivers/vfio/pci/vfio_pci.c
> > @@ -90,6 +90,7 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev)
> >  		vdev->has_vga = true;
> >  #endif
> >  
> > +	pdev->dev_flags |= PCI_DEV_FLAGS_ASSIGNED;
> >  	return 0;
> >  }
> >  
> > @@ -149,6 +150,7 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev)
> >  				__func__, dev_name(&pdev->dev), ret);
> >  	}
> >  
> > +	pdev->dev_flags &= ~PCI_DEV_FLAGS_ASSIGNED;
> >  	pci_restore_state(pdev);
> >  }
> >  
> 
>