[PATCH v8 00/12] iommu: Shared Virtual Addressing for SMMUv3 (PT sharing part)

[Jean-Philippe Brucker]

On Mon, Jul 20, 2020 at 12:11:17PM +0100, Will Deacon wrote:
> On Thu, Jun 18, 2020 at 05:51:13PM +0200, Jean-Philippe Brucker wrote:
> > Since v7 [1], I split the series into three parts to ease review. This
> > first one adds page table sharing to the SMMUv3 driver. The second one
> > adds support for I/O page faults through PRI and Stall, and the last one
> > adds additional and optional features (DVM, VHE and HTTU). SVA needs the
> > three parts to work. No significant change apart from that, I just
> > addressed the previous comments.
> > 
> > I'd rather everything went through the IOMMU tree but I'm assuming patch
> > 1 will also go through the x86 tree as part of [2]. It is definitely
> > required by patch 3 which is required by patch 11. I don't know how this
> > kind of conflict is usually resolved, but if it's a problem I could
> > further shrink the series to only patches 4-10 this cycle.
> 
> Modulo my review comments, I think most of this looks alright from the SMMU
> side. However, I would really like it if the SVA driver parts could be moved
> into a separate file (e.g. arm-smmu-v3-sva.c), with a separate config option
> (dependent on the current one, so you can easily build a driver without SVA
> support). Does that sound remotely feasible?

Yes it makes sense. It requires moving some definitions from arm-smmu-v3.c
to a .h but should be straightforward, I'll give it a try.

Thanks,
Jean

> If so, I think it would really
> help in terms of maintainability, since the SVA model is really all about
> the mm, whereas the driver model is all about the device. This makes it
> really hard to read when you have to keep working out whether the current
> 'handle' is an mm_struct or an arm_smmu_device.
> 
> Will