[PATCH 6/9] iommu/arm-smmu: Support buggy implemenations where all config accesses are secure

Andreas Herrmann andreas.herrmann at calxeda.com
Fri Sep 27 09:48:09 EDT 2013


On Fri, Sep 27, 2013 at 09:05:28AM -0400, Will Deacon wrote:
> On Thu, Sep 26, 2013 at 11:36:18PM +0100, Andreas Herrmann wrote:
> > In such a case we have to use secure aliases of some non-secure
> > registers.
> > 
> > This behaviour is controlled via a flag in smmu->bugs. It is set
> > based on DT information when probing an SMMU device.
> 
> :(
> 
> I guess my main comment is just some understanding on how things are wired.
> It's *just* the configuration access that is secure, right?

Correct.

> Device transactions are non-secure, so the existing TLB invalidation
> code will work correctly?

Yes, transactions are non-secure.

The TLB invalidation code (using SMMU_TLBIVMID for stage2) also seems
too work -- no problems triggered so far (neither with sata nor with
xgmac).


Andreas



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