[PATCH v6 06/11] PCI: portdrv: Set driver_managed_dma

Lu Baolu
2022-02-18T00:58:29Z

If a switch lacks ACS P2P Request Redirect, a device below the switch can
bypass the IOMMU and DMA directly to other devices below the switch, so
all the downstream devices must be in the same IOMMU group as the switch
itself.

The existing VFIO framework allows the portdrv driver to be bound to the
bridge while its downstream devices are assigned to user space. The
pci_dma_configure() marks the IOMMU group as containing only devices
with kernel drivers that manage DMA. Avoid this default behavior for the
portdrv driver in order for compatibility with the current VFIO usage.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Suggested-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
drivers/pci/pcie/portdrv_pci.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c
index 35eca6277a96..6b2adb678c21 100644
--- a/drivers/pci/pcie/portdrv_pci.c
+++ b/drivers/pci/pcie/portdrv_pci.c
@@ -202,6 +202,8 @@ static struct pci_driver pcie_portdriver = {

.err_handler = &pcie_portdrv_err_handler,

+ .driver_managed_dma = true,
+
.driver.pm = PCIE_PORTDRV_PM_OPS,
};

--
2.25.1