[PATCH 0/1][SRU][J] use IOMMU passthrough mode for Intel IPUs

[You-Sheng Yang]

BugLink: https://bugs.launchpad.net/bugs/1958004

[Impact]

Intel iommu was turned on by default in mainline build v5.15.5 or jammy
-generic kernel 5.15.0-12.12. This would breaks IPU6.

[ 6.681241] intel-ipu6 intel-ipu: IPU driver version 1.0
[ 7.056166] DMAR: DRHD: handling fault status reg 2
[ 7.056169] DMAR: [DMA Read NO_PASID] Request device [00:05.0] fault
addr 0x11b1d4000 [fault reason 0x06] PTE Read access is not set
[ 7.056421] DMAR: DRHD: handling fault status reg 2
[ 7.056422] DMAR: [DMA Read NO_PASID] Request device [00:05.0] fault
addr 0x3fffffff000 [fault reason 0x06] PTE Read access is not set
[ 7.056456] intel-ipu6-psys intel-ipu6-psys0: pkg_dir entry count:8
[ 7.056637] intel-ipu6-psys intel-ipu6-psys0: psys probe minor: 0
[ 7.056652] DMAR: DRHD: handling fault status reg 2
[ 7.056653] DMAR: [DMA Read NO_PASID] Request device [00:05.0] fault
addr 0x3fffffff000 [fault reason 0x06] PTE Read access is not set
[ 7.056882] DMAR: DRHD: handling fault status reg 2
[ 8.197149] intel-ipu6-isys intel-ipu6-isys0: isys port open ready
failed -16
[ 8.197157] intel-ipu6-isys intel-ipu6-isys0: Device close failure: -16
[ 10.201677] intel-ipu6-isys intel-ipu6-isys0: Device release time out
-16
[ 10.240523] intel-ipu6-isys intel-ipu6-isys0: Clearing old context

[Fix]

Use IOMMU passthrough mode for IPU6 as it has its own iommu hardware.

[Test Case]

Apply the fix and kernel should print a new info line:

  Passthrough IOMMU for integrated Intel IPU

and IPU6 camera should continue to work without intel_iommu=off
work-around.

[Where problems could occur]

No. That's what it should have been done.

[Other Info]

This only affects kernel >= 5.15, so only Jammy is nominated.

Intel IPU6 driver has been proposed for Jammy for hwe-5.15 migration in
bug 1955383
(https://lists.ubuntu.com/archives/kernel-team/2021-December/126749.html).
The port for 5.17 unstable would be filed soon. Still under discussion.

While there is no plan for Intel to upstream Intel IPU6 driver before
kernel camera API is out, these extra prerequisite patches will only be
staged in a separate patches folder in the upstream repository.

zouxiaoh (1):
  UBUNTU: SAUCE: iommu: intel-ipu: use IOMMU passthrough mode for Intel
    IPUs

 drivers/iommu/intel/iommu.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

-- 
2.34.1