Re: [PATCH 1/1] iommu/vt-d: Enable PCI ACS for platform opt in hint

[Mika Westerberg]

On Tue, Jun 09, 2020 at 07:17:20AM +0800, Lu Baolu wrote:
> PCI ACS is disabled if Intel IOMMU is off by default or intel_iommu=off
> is used in command line. Unfortunately, Intel IOMMU will be forced on if
> there're devices sitting on an external facing PCI port that is marked
> as untrusted (for example, thunderbolt peripherals). That means, PCI ACS
> is disabled while Intel IOMMU is forced on to isolate those devices. As
> the result, the devices of an MFD will be grouped by a single group even
> the ACS is supported on device.
> 
> [    0.691263] pci 0000:00:07.1: Adding to iommu group 3
> [    0.691277] pci 0000:00:07.2: Adding to iommu group 3
> [    0.691292] pci 0000:00:07.3: Adding to iommu group 3
> 
> Fix it by requesting PCI ACS when Intel IOMMU is detected with platform
> opt in hint.
> 
> Fixes: 89a6079df791a ("iommu/vt-d: Force IOMMU on for platform opt in hint")
> Cc: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>

Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>