Re: [PATCH v5] iommu/io-pgtable-arm: Add support for contiguous hint bit

[Jason Gunthorpe]

On Mon, Sep 21, 2026 at 04:44:07PM +0530, Vijayanand Jitta wrote:
> From: Prakash Gupta <prakash.gupta@xxxxxxxxxxxxxxxx>
> 
> 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, set CONT on every descriptor in that group so the hardware can
> combine translations and improve TLB reach.
> 
> Advertise the supported CONT group sizes in pgsize_bitmap. Callers select
> those sizes through the normal page-size selection path; io-pgtable-arm
> then installs the corresponding tagged descriptors directly. A partial
> unmap of a tagged CONT group is rejected before modifying any descriptor,
> so a rejected request cannot leave the group partly unmapped.
> 
> The IO_PGTABLE_QUIRK_ARM_NO_CONT_HINT quirk allows SMMU drivers to disable
> CONT support for hardware with implementation-specific errata.

smmuv3 has this errata, it must be disabled there too. I didn't notice
it in this patch?

Jason