Hi Robin,
On Thu, Jan 26, 2017 at 12:23 PM, Robin Murphy <robin.murphy@xxxxxxx> wrote:
> On 26/01/17 09:53, Geert Uytterhoeven wrote:
>> Currently, the IPMMU/VMSA driver supports 32-bit I/O Virtual Addresses
>> only, and thus sets io_pgtable_cfg.ias = 32. However, it doesn't force
>> a 32-bit IOVA space through the IOMMU Domain Geometry.
>>
>> Hence if a device (e.g. SYS-DMAC) rightfully configures a 40-bit DMA
>> mask, it will still be handed out a 40-bit IOVA, outside the 32-bit IOVA
>> space, leading to out-of-bounds accesses of the PGD when mapping the
>> IOVA.
>>
>> Force a 32-bit IOMMU Domain Geometry to fix this.
>
> Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
Thanks!
>> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
>> ---
>> Should the generic code restrict the geometry based on IAS instead?
>
> Which generic code? IAS is specific to the io-pgtable library (well,
> really it's an ARM-SMMU-ism, but "input address size" is a fairly
> portable concept), but io-pgtable is just factored-out driver helper
> code and doesn't know anything about iommu_domains and the IOMMU API.
> Conversely, the IOMMU API core and kernel code beyond also know nothing
> about io-pgtable internals - in fact the domain geometry *is* how the
> IOMMU driver communicates its configured address space size to the
> outside world.
OK, so the IPMMU/VMSA does have to take care of it itself.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
