On Wed, Aug 30, 2017 at 03:05:59PM -0600, Jon Derrick wrote:
> VMD child devices must use the VMD endpoint's ID as the requester.
> Because of this, there needs to be a way to link the parent VMD
> endpoint's iommu group and associated mappings to the VMD child devices
> such that attaching and detaching child devices modify the endpoint's
> mappings, while preventing early detaching on a singular device removal
> or unbinding.
> 
> The reassignment of individual VMD child devices devices to VMs is
> outside the scope of VMD, but may be implemented in the future. For now
> it is best to prevent any such attempts.
> 
> This patch prevents VMD child devices from returning an IOMMU, which
> prevents it from exposing an iommu_group sysfs directories and allowing
> subsequent binding by userspace-access drivers such as VFIO.
> 
> Signed-off-by: Jon Derrick <jonathan.derr...@intel.com>

Applied to pci/host-vmd for v4.14, thanks!

> ---
> v2->3, wrapped in x86 ifdef to avoid ia64 compilation errors
> 
>  drivers/iommu/intel-iommu.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 687f18f..2800a6e 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -901,6 +901,13 @@ static struct intel_iommu *device_to_iommu(struct device 
> *dev, u8 *bus, u8 *devf
>               struct pci_dev *pf_pdev;
>  
>               pdev = to_pci_dev(dev);
> +
> +#ifdef CONFIG_X86
> +             /* VMD child devices currently cannot be handled individually */
> +             if (is_vmd(pdev->bus))
> +                     return NULL;
> +#endif
> +
>               /* VFs aren't listed in scope tables; we need to look up
>                * the PF instead to find the IOMMU. */
>               pf_pdev = pci_physfn(pdev);
> -- 
> 1.8.3.1
> 
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