Re: [PATCH v3 5/8] iommufd: Associate fault object with iommufd_hw_pgtable

[Jason Gunthorpe]

On Thu, Mar 07, 2024 at 09:54:53AM +0800, Baolu Lu wrote:
> On 2024/3/7 0:01, Jason Gunthorpe wrote:
> > On Wed, Mar 06, 2024 at 11:15:50PM +0800, Zhangfei Gao wrote:
> > > Double checked, this does not send flags, 0 is OK,
> > > Only domain_alloc_user in iommufd_hwpt_paging_alloc requires flags.
> > > 
> > > In my debug, I need this patch, otherwise NULL pointer errors happen
> > > since SVA is not set.
> > This is some driver bug, we need to get rid of these
> > iommu_dev_enable_feature() requirements.
> 
> Yes. Especially iopf should be independent of SVA.
> 
> The problem in the arm smmu v3 driver is that enabling iopf is actually
> done in the enabling SVA path, while the enabling iopf path does nothing
> except for some checks. It doesn't matter if iopf is tied with SVA, but
> when it comes to delivering iopf to user space, we need to decouple it.

Yes. Each driver is going to need to get a to a NOP for the feature
things then we can remove them.

I did half the ARM driver in my part 2, the iopf bit still needs
doing there.

Jason