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

[Will Deacon]

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? 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