Re: [ACS PATCH v5 1/2] acs p2p upsteram forwarding enabling

[Chris Wright <chrisw@sous-sol.org>]

* Allen Kay (allen.m.kay@intel.com) wrote:
> Changes from v4 to v5:
> 	- separate out dom0 checking out of v4
> 	- use iommu_found() for detecting HW iommu presence

Erk, turns out iommu_found() doesn't work (becuase the iommu has been
detected, but not initialized yet when this code runs).

This could be fixed in a few ways:

1) Have an isolation capable iommu actively ask for ACS to be enabled
2) Have pci core switch to iommu_detected (as Allen had done earlier).
This would need some work to make iommu_detected actually defined on
all arches that make use of pci.  iommu_detected could be more
descriptive than a single boolean, turned into an enum that says what
kind of hw iommu was detected.
3) Just always enable ACS and pay the price.

I'll send a patch for option 1) momentarily.

Thoughts?

thanks,
-chris