iommu/fsl: Use driver_managed_dma to allow VFIO to work

iommu/fsl: Use driver_managed_dma to allow VFIO to work

The FSL driver is mangling the iommu_groups to not have a group for its
PCI bridge/controller (eg the thing passed to fsl_add_bridge()). Robin
says this is so FSL could work with VFIO which would be blocked by having
a probed driver on the platform_device in the same group. This is
supported by comments from FSL:

 https://lore.kernel.org/all/C5ECD7A89D1DC44195F34B25E172658D459471@039-SN2MPN1-013.039d.mgd.msft.net

 ..  PCIe devices share the same device group as the PCI controller. This
  becomes a problem while assigning the devices to the guest, as you are
  required to unbind all the PCIe devices including the controller from the
  host. PCIe controller can't be unbound from the host, so we simply delete
  the controller iommu_group.

However, today, we use driver_managed_dma to allow PCI infrastructure
devices that are 'security safe' to co-exist in groups and still allow
VFIO to work. Set this flag for the fsl_pci_driver.

Change fsl_pamu_device_group() so that it no longer removes the controller
from any groups. For check_pci_ctl_endpt_part() mode this creates an extra
group that contains only the controller.

Otherwise force the controller's single group to be the group of all the
PCI devices on the controller's hose. VFIO continues to work because of
driver_managed_dma.

Remove the iommu_group_remove_device() calls from fsl_pamu and lightly
restructure its fsl_pamu_device_group() function.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/3-v2-ce71068deeec+4cf6-fsl_rm_groups_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>