Re: [PATCH] iommu/io-pgtable-arm: Add support for contiguous hint bit

[Jason Gunthorpe <jgg@nvidia.com>]

On Wed, Jul 15, 2026 at 11:25:42AM +0530, Vijayanand Jitta wrote:
> On 7/3/2026 9:42 PM, Jason Gunthorpe wrote:
> > On Thu, Jun 18, 2026 at 02:32:09PM +0530, Vijayanand Jitta wrote:
> >> From: Prakash Gupta <prakash.gupta@oss.qualcomm.com>
> >>
> >> Add support for the contiguous hint (CONT) bit in ARM LPAE page tables.
> >> When a set of consecutive PTEs map a naturally-aligned contiguous block
> >> of memory, the CONT bit can be set on all entries in the group to allow
> >> the hardware to combine them into a single TLB entry, improving TLB
> >> utilization.
> >>
> >> The contiguous hint sizes per granule are:
> >>
> >>   Page Size | CONT PTE |  PMD  | CONT PMD
> >>   ----------+----------+-------+---------
> >>       4K    |   64K    |   2M  |   32M
> >>      16K    |    2M    |  32M  |    1G
> >>      64K    |    2M    | 512M  |   16G
> > 
> > My series to convert smmuv3 to the iommupt takes care of this and
> > supports all the orders too. I'd rather we move forward with that then
> > try to patch up this.
> 
> Thanks for details, I have gone through your series. As this patch
> targets io-pgtable-arm.c directly and would benefit all its users (SMMUv2,
> Apple DART, etc.), not just SMMUv3. I think there will still be value in
> this patch for the other users.

If other users care they should also be converted to iommupt, there
are many benefits to this besides just cont support.

Jason