[PATCH 3/6] vfio: remove the unused mdev iommu hook
Jason Gunthorpe
jgg at ziepe.ca
Thu May 13 05:00:58 PDT 2021
On Thu, May 13, 2021 at 03:28:52AM +0000, Tian, Kevin wrote:
> Are you specially concerned about this iommu_device hack which
> directly connects mdev_device to iommu layer or the entire removed
> logic including the aux domain concept? For the former we are now
> following up the referred thread to find a clean way. But for the latter
> we feel it's still necessary regardless of how iommu interface is redesigned
> to support device connection from the upper level driver. The reason is
> that with mdev or subdevice one physical device could be attached to
> multiple domains now. there could be a primary domain with DOMAIN_
> DMA type for DMA_API use by parent driver itself, and multiple auxiliary
> domains with DOMAIN_UNMANAGED types for subdevices assigned to
> different VMs.
Why do we need more domains than just the physical domain for the
parent? How does auxdomain appear in /dev/ioasid?
I never understood what this dead code was supposed to be used for.
Jason
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