On Mon, 28 Feb 2022 08:50:52 +0800 Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> wrote: > 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@xxxxxxxxxxxxxxx> > Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx> > --- > drivers/vfio/fsl-mc/vfio_fsl_mc.c | 1 + > drivers/vfio/pci/vfio_pci.c | 1 + > drivers/vfio/platform/vfio_amba.c | 1 + > drivers/vfio/platform/vfio_platform.c | 1 + > drivers/vfio/vfio.c | 10 +++++++++- > 5 files changed, 13 insertions(+), 1 deletion(-) Acked-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
