Virtualization - Mar 2021 - [Freedreno] [PATCH 16/17] iommu: remove DOMAIN_ATTR_IO_PGTABLE_CFG

On Thu, Mar 04, 2021 at 03:11:08PM -0800, Rob Clark
wrote:
> On Thu, Mar 4, 2021 at 7:48 AM Robin Murphy <robin.murphy at arm.com>
wrote:
> >
> > On 2021-03-01 08:42, Christoph Hellwig wrote:
> > > Signed-off-by: Christoph Hellwig <hch at lst.de>
> >
> > Moreso than the previous patch, where the feature is at least
relatively
> > generic (note that there's a bunch of in-flight development around
> > DOMAIN_ATTR_NESTING), I'm really not convinced that it's
beneficial to
> > bloat the generic iommu_ops structure with private driver-specific
> > interfaces. The attribute interface is a great compromise for these
> > kinds of things, and you can easily add type-checked wrappers around
it
> > for external callers (maybe even make the actual attributes internal
> > between the IOMMU core and drivers) if that's your concern.
> 
> I suppose if this is *just* for the GPU we could move it into
adreno_smmu_priv..
> 
> But one thing I'm not sure about is whether
> IO_PGTABLE_QUIRK_ARM_OUTER_WBWA is something that other devices
> *should* be using as well, but just haven't gotten around to yet.
The intention is certainly that this would be a place to collate per-domain
pgtable quirks, so I'd prefer not to tie that to the GPU.

Will

On Fri, Mar 05, 2021 at 10:00:12AM +0000, Will Deacon
wrote:
> > But one thing I'm not sure about is whether
> > IO_PGTABLE_QUIRK_ARM_OUTER_WBWA is something that other devices
> > *should* be using as well, but just haven't gotten around to yet.
> 
> The intention is certainly that this would be a place to collate per-domain
> pgtable quirks, so I'd prefer not to tie that to the GPU.
So the overall consensus is to just keep this as-is for now?