Re: [Xen-devel] [PATCH v4 3/3] xen/iommu: arm: Use p2m_ipa_bits as stage2 input size

["Edgar E. Iglesias" <edgar.iglesias@xxxxxxxxx>]

On Tue, May 05, 2015 at 03:30:10PM +0100, Julien Grall wrote:
> On 05/05/15 14:59, Ian Campbell wrote:
> > On Tue, 2015-05-05 at 14:48 +0100, Julien Grall wrote:
> >>> Do we need to also check that we are configuring the same number of
> >>> levels of PT etc, or is that already handled?
> >>
> >> The SMMU only care about the number of IPA bits.
> > 
> > What ensures that the starting level of the SMMU matches the starting
> > level of the MMU-s2?
> 
> Nothing, it's hardcoded in the SMMU driver for now :/.
> 
> It's assuming SL0 = 1 which works fine for ARM32 but would be an issue
> on platform with IPA >= 44 bits.
> 
> S2 output size may need to be restrict too depending of the PA bits.

Right, these could cause problems.

I've sent out a v5 of the ipa size series.
I can have a look at these other MMU settings and send follow-up patches if
there is interest?

Cheers,
Edgar

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