Re: [PATCH 0/5] Legacy direct-assign mode

["Derrick, Jonathan" <jonathan.derrick@intel.com>]

On Mon, 2021-03-22 at 12:28 +0000, Lorenzo Pieralisi wrote:
> On Fri, Nov 20, 2020 at 03:51:39PM -0700, Jon Derrick wrote:
> > This set adds a legacy direct-assign mode. Newer enterprise hardware has
> > physical addressing hints to assist device passthrough to guests that needs to
> > correctly program bridge windows with physical addresses. Some customers are
> > using a legacy method that relies on the VMD subdevice domain's root port
> > windows to be written with the physical addresses. This method also allows
> > other hypervisors besides QEMU/KVM to perform guest passthrough.
> > 
> > This patchset adds a host and guest mode to write the physical address
> > information to the root port registers in the host and read them in the guest,
> > and restore them in both cases on module unload.
> > 
> > This patchset also folds in the VMD subdevice domain secondary bus reset
> > patchset [1] to clear the domain prior to guest passthrough.
> > 
> > [1] https://patchwork.kernel.org/project/linux-pci/cover/20200928010557.5324-1-jonathan.derrick@intel.com/
> > 
> > Jon Derrick (5):
> >   PCI: vmd: Reset the VMD subdevice domain on probe
> >   PCI: Add a reset quirk for VMD
> >   PCI: vmd: Add offset translation helper
> >   PCI: vmd: Pass features to vmd_get_phys_offsets()
> >   PCI: vmd: Add legacy guest passthrough mode
> > 
> >  drivers/pci/controller/vmd.c | 200 ++++++++++++++++++++++++++++++++++++++-----
> >  drivers/pci/quirks.c         |  48 +++++++++++
> >  2 files changed, 227 insertions(+), 21 deletions(-)
> 
> Hi Jon,
> 
> it is unclear to me where we are with this series, please let me know.
> 
> Thanks,
> Lorenzo

Hi Lorenzo,

We can drop this series for now. We may revive it in the future with
modifications to the reset sequence.

Best,
Jon