From: Zhenzhong Duan <[email protected]> Add documentation about using IOMMUFD backed VFIO device with intel_iommu with x-flts=on.
Suggested-by: Yi Liu <[email protected]> Signed-off-by: Zhenzhong Duan <[email protected]> Reviewed-by: Eric Auger <[email protected]> Reviewed-by: Yi Liu <[email protected]> Reviewed-by: Michael S. Tsirkin <[email protected]> Link: https://lore.kernel.org/qemu-devel/[email protected] Signed-off-by: Cédric Le Goater <[email protected]> --- 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 b37098e1b625d9be0368e53b7492db64828c88c3..2d6e60dce1d38f1de136c3d65f3c396aef9e0805 100644 --- a/docs/devel/vfio-iommufd.rst +++ b/docs/devel/vfio-iommufd.rst @@ -152,3 +152,20 @@ RAM discarding for mdev. ``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=on +------------------------------------------ + +Only IOMMUFD backed VFIO device is supported when intel_iommu is configured +with x-flts=on, for legacy container backed VFIO device, below error shows: + +.. code-block:: none + + qemu-system-x86_64: -device vfio-pci,host=0000:02:00.0: vfio 0000:02:00.0: Failed to set vIOMMU: Need IOMMUFD backend when x-flts=on + +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=0000:02:00.0,bus=bridge1,iommufd=iommufd0: vfio 0000:02:00.0: Failed to set vIOMMU: Host device downstream to a PCI bridge is unsupported when x-flts=on -- 2.52.0
