Re: [PATCH V4 05/18] iommu/ioasid: Redefine IOASID set and allocation APIs

[Kirti Wankhede]

On 5/26/2021 1:22 AM, Jason Gunthorpe wrote:
> On Wed, May 26, 2021 at 12:56:30AM +0530, Kirti Wankhede wrote:
>
> > 2. iommu backed mdev devices for SRIOV where mdev device is created per
> > VF (mdev device == VF device) then that mdev device has same iommu
> > protection scope as VF associated to it.
>
> This doesn't require, and certainly shouldn't create, a fake group.
>
> Only the VF's real IOMMU group should be used to model an iommu domain
> linked to a VF. Injecting fake groups that are proxies for real groups
> only opens the possibility of security problems like David is
> concerned with.

I think this security issue should be addressed by letting mdev device 
inherit its parent's iommu_group, i.e. VF's iommu_group here.

Kirti

> Max's series approaches this properly by fully linking the struct
> pci_device of the VF throughout the entire VFIO scheme, including the
> group and container, while still allowing override of various VFIO
> operations.
>
> Jason