Re: [PATCH v3 1/2] iommu/amd: Remove PT_FEAT_DYNAMIC_TOP from PT_FORCE_ENABLED_FEATURES

[Jason Gunthorpe]

On Wed, Mar 11, 2026 at 09:54:55PM +0530, Vasant Hegde wrote:
> 
> + Jason
> 
> On 3/9/2026 7:35 PM, Ankit Soni wrote:
> > Dynamic top is used to grow the page table levels. However, if the VA
> > size is small and the initial page table level already covers the entire
> > address space, table growth is not required. In that case, the generic
> > page table framework clears PT_FEAT_DYNAMIC_TOP, which in turn causes
> > error -EOPNOTSUPP and leads to domain initialization failure.
> > 
> > Remove PT_FEAT_DYNAMIC_TOP from PT_FORCE_ENABLED_FEATURES, since during
> > domain allocation AMD IOMMU driver explicitly sets PT_FEAT_DYNAMIC_TOP
> > via cfg.common.features, this keeps normal runtime behavior unchanged.
> > 
> 
> Fixes: 879ced2bab1 ("iommupt: Add the AMD IOMMU v1 page table format")

No.. There is no bug here.

I don't really understand why you'd want to do this, the driver still
sets PT_FEAT_DYNAMIC_TOP, so what is the issue?

It shouldn't be removed from PT_FORCE_ENABLED_FEATURES, something else
is wrong.

Jason