linux/drivers/vfio/platform
Lu Baolu 70693f4708 vfio: Set DMA ownership for VFIO devices
Claim group dma ownership when an IOMMU group is set to a container,
and release the dma ownership once the iommu group is unset from the
container.

This change disallows some unsafe bridge drivers to bind to non-ACS
bridges while devices under them are assigned to user space. This is an
intentional enhancement and possibly breaks some existing
configurations. The recommendation to such an affected user would be
that the previously allowed host bridge driver was unsafe for this use
case and to continue to enable assignment of devices within that group,
the driver should be unbound from the bridge device or replaced with the
pci-stub driver.

For any bridge driver, we consider it unsafe if it satisfies any of the
following conditions:

  1) The bridge driver uses DMA. Calling pci_set_master() or calling any
     kernel DMA API (dma_map_*() and etc.) is an indicate that the
     driver is doing DMA.

  2) If the bridge driver uses MMIO, it should be tolerant to hostile
     userspace also touching the same MMIO registers via P2P DMA
     attacks.

If the bridge driver turns out to be a safe one, it could be used as
before by setting the driver's .driver_managed_dma field, just like what
we have done in the pcieport driver.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/r/20220418005000.897664-8-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2022-04-28 15:32:20 +02:00
..
reset Merge branches 'v5.15/vfio/spdx-license-cleanups', 'v5.15/vfio/dma-valid-waited-v3', 'v5.15/vfio/vfio-pci-core-v5' and 'v5.15/vfio/vfio-ap' into v5.15/vfio/next 2021-08-26 11:08:50 -06:00
Kconfig vfio: Use kconfig if XX/endif blocks instead of repeating 'depends on' 2021-08-26 10:36:51 -06:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
vfio_amba.c vfio: Set DMA ownership for VFIO devices 2022-04-28 15:32:20 +02:00
vfio_platform_common.c vfio: Move vfio_iommu_group_get() to vfio_register_group_dev() 2021-09-30 12:46:43 -06:00
vfio_platform_irq.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174 2019-05-30 11:26:41 -07:00
vfio_platform_private.h vfio/platform: Use open_device() instead of open coding a refcnt scheme 2021-08-11 09:50:11 -06:00
vfio_platform.c vfio: Set DMA ownership for VFIO devices 2022-04-28 15:32:20 +02:00