Hi Joerg,

On Mon, Sep 07, 2020 at 08:54:44PM -0700, Prakhya, Sai Praneeth wrote:
> Presently, the default domain of an iommu group is allocated during boot time
> and it cannot be changed later. So, the device would typically be either in
> identity (pass_through) mode or the device would be in DMA mode as long as the
> system is up and running. There is no way to change the default domain type
> dynamically i.e. after booting, a device cannot switch between identity mode 
> and
> DMA mode.
> Assume a use case wherein the privileged user would want to use the device in
> pass-through mode when the device is used for host so that it would be high
> performing. Presently, this is not supported. Hence add support to change the
> default domain of an iommu group dynamically.
> Support this by writing to a sysfs file, namely
> "/sys/kernel/iommu_groups/<grp_id>/type".
> Testing:
> --------
> Tested by dynamically changing storage device (nvme) from
> 1. identity mode to DMA and making sure file transfer works
> 2. DMA mode to identity mode and making sure file transfer works
> Tested only for intel_iommu/vt-d. Would appreciate if someone could test on 
> and ARM based machines.

Just trying to followup on this series.

Sai has moved out of Intel, hence I'm trying to followup on his behalf.

Let me know if you have queued this for the next release.

> Based on iommu maintainer's 'next' branch.
> Changes from V6:
> ----------------
> 1. None except for version bump.

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