[Intel-gfx] [PATCH v5 09/19] vfio/pci: Allow passing zero-length fd array in VFIO_DEVICE_PCI_HOT_RESET

[Liu, Yi L]

> From: Jason Gunthorpe <jgg at nvidia.com>
> Sent: Tuesday, February 28, 2023 2:23 AM
> 
> On Mon, Feb 27, 2023 at 03:11:25AM -0800, Yi Liu wrote:
> > to indicate kernel to use the device's bound iommufd_ctx for the device
> > ownership check. Kernel should loop all the opened devices in the
> dev_set,
> > and check if they are bound to the same iommufd_ctx. For the devices
> that
> > has not been opened yet but affected, they can be reset by the current
> > users as they cannot be opened by any other user. This applies to the
> > existing group/container path as well.
> >
> > Suggested-by: Jason Gunthorpe <jgg at nvidia.com>
> > Signed-off-by: Yi Liu <yi.l.liu at intel.com>
> > ---
> >  drivers/vfio/pci/vfio_pci_core.c | 111 +++++++++++++++++++++++-------
> -
> >  drivers/vfio/vfio.h              |  11 +++
> >  include/uapi/linux/vfio.h        |  16 +++++
> >  3 files changed, 109 insertions(+), 29 deletions(-)
> >
> > diff --git a/drivers/vfio/pci/vfio_pci_core.c
> b/drivers/vfio/pci/vfio_pci_core.c
> > index 1bf54beeaef2..e0ebe55b4df0 100644
> > --- a/drivers/vfio/pci/vfio_pci_core.c
> > +++ b/drivers/vfio/pci/vfio_pci_core.c
> > @@ -27,11 +27,13 @@
> >  #include <linux/vgaarb.h>
> >  #include <linux/nospec.h>
> >  #include <linux/sched/mm.h>
> > +#include <linux/iommufd.h>
> 
> Is this needed anymore?

No more. Will remove it.

> >  #if IS_ENABLED(CONFIG_EEH)
> >  #include <asm/eeh.h>
> >  #endif
> >
> >  #include "vfio_pci_priv.h"
> > +#include "../vfio.h"
> 
> Don't do this, put vfio_device_iommufd() in the normal public header

Ok. will put it in include/linux/vfio.h

> > diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> > index 0552e8dcf0cb..4bf11ee8de53 100644
> > --- a/include/uapi/linux/vfio.h
> > +++ b/include/uapi/linux/vfio.h
> > @@ -673,6 +673,22 @@ struct vfio_pci_hot_reset_info {
> >   * VFIO_DEVICE_PCI_HOT_RESET - _IOW(VFIO_TYPE, VFIO_BASE + 13,
> >   *				    struct vfio_pci_hot_reset)
> >   *
> > + * Userspace requests hot reset for the devices it uses.  Due to the
> > + * underlying topology, multiple devices may be affected in the reset.
> > + * The affected devices may have been opened by the user or by other
> > + * users or not opened yet.  Only when all the affected devices are
> > + * either opened by the current user or not opened by any user, should
> > + * the reset request be allowed.  Otherwise, this request is expected
> > + * to return error.
> > + *
> > + * If the user uses group and container interface, it should pass down
> > + * a set of group fds for ownership check.  If the user uses iommufd, it
> > + * should pass down a zero-length group_fds array to indicate the kernel
> > + * to use the bound iommufd for the ownership check.  User that uses
> the
> > + * vfio iommufd compatible mode can also pass down a zero-length
> group_fds
> > + * array as this mode uses iommufd in kernel, and there is no reason to
> > + * forbide it.
> 
> 'forbid'

Oh, yes. will correct it.

Regards,
Yi Liu