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charset="utf-8" Add documentation about using IOMMUFD backed VFIO device with intel_iommu w= ith x-flts=3Don. Suggested-by: Yi Liu Signed-off-by: Zhenzhong Duan Reviewed-by: Eric Auger --- docs/devel/vfio-iommufd.rst | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/docs/devel/vfio-iommufd.rst b/docs/devel/vfio-iommufd.rst index 3d1c11f175..cbf59924ba 100644 --- a/docs/devel/vfio-iommufd.rst +++ b/docs/devel/vfio-iommufd.rst @@ -164,3 +164,20 @@ RAM discarding for mdev. =20 ``vfio-ap`` and ``vfio-ccw`` devices don't have same issue as their backend devices are always mdev and RAM discarding is force enabled. + +Usage with intel_iommu featuring x-flts=3Don +------------------------------------------ + +Only IOMMUFD backed VFIO device is supported when intel_iommu is configured +with x-flts=3Don, for legacy container backed VFIO device, below error sho= ws: + +.. code-block:: none + + qemu-system-x86_64: -device vfio-pci,host=3D0000:02:00.0: vfio 0000:02= :00.0: Failed to set vIOMMU: Need IOMMUFD backend when x-flts=3Don + +VFIO device under PCI bridge is unsupported, use PCIE bridge if necessary, +otherwise below error shows: + +.. code-block:: none + + qemu-system-x86_64: -device vfio-pci,host=3D0000:02:00.0,bus=3Dbridge1= ,iommufd=3Diommufd0: vfio 0000:02:00.0: Failed to set vIOMMU: Host device d= ownstream to a PCI bridge is unsupported when x-flts=3Don --=20 2.47.1