Re: [PATCH] iommu/of: Fix of_iommu_configure() for disabled IOMMUs

From: Sudeep Holla
Date: Fri Aug 04 2017 - 08:57:35 EST

On 04/08/17 12:16, Robin Murphy wrote:
> Sudeep reports that the logic is slightly broken when a PCI iommu-map
> entry targets an IOMMU marked as disabled in DT, since of_pci_map_rid()
> succeeds in following a phandle, and of_iommu_xlate() doesn't return an
> error value, but we miss checking whether ops was actually non-NULL.
> Whilst this could be solved with a point fix in of_pci_iommu_init(), it
> suggests that all the juggling of ERR_PTR values through the ops pointer
> is proving rather too complicated for its own good, so let's instead
> simplify the whole flow (with a side-effect of eliminating the cause of
> the bug).
> The fact that we now rely on iommu_fwspec means that we no longer need
> to pass around an iommu_ops pointer at all - we can simply propagate a
> regular int return value until we know whether we have a viable IOMMU,
> then retrieve the ops from the fwspec if and when we actually need them.
> This makes everything a bit more uniform and certainly easier to follow.
> Reported-by: Sudeep Holla <sudeep.holla@xxxxxxx>

Tested-by: Sudeep Holla <sudeep.holla@xxxxxxx>