Re: [PATCH v6 0/8] dma: swiotlb: Centralize default pool policy and sizing

[Marek Szyprowski]

On 24.09.2026 08:07, Aneesh Kumar K.V (Arm) wrote:
> This series centralizes swiotlb default-pool selection and sizing, and
> simplifies the initialization flags used to describe pool placement.
>
> The first patch replaces the addressing-limit argument with initialization
> flags and introduces explicit policies for the different reasons a default
> pool may be needed. Architectures now report DMA addressing constraints with
> SWIOTLB_INIT_ADDRESSING_LIMIT, while the core selects the corresponding pool
> policy.
>
> The second patch moves the reduced sizing used when the pool is needed only
> for unaligned kmalloc bouncing from arm64 and RISC-V into the swiotlb core.
>
> The third patch centralizes swiotlb sizing for memory-encrypted systems. It
> moves the existing x86 guest-sizing policy into the core. Host memory
> encryption retains the normal pool size, and a shared default pool is not
> selected solely for guest memory encryption when a restricted DMA pool is
> present.
>
> The fourth patch removes SWIOTLB_ANY. Pool placement is derived directly from
> SWIOTLB_INIT_ADDRESSING_LIMIT: pools required for limited DMA addressing are
> allocated below the architecture's low address limit, while other pools may
> be allocated anywhere in directly mapped memory. Xen continues to request a
> pool explicitly with SWIOTLB_INIT_REMAP without imposing a low-address
> constraint.


I will give this patchset a chance in linux-next. If one feels that it still needs
to be improved or sees any other reason why it shouldn't be merged, let me know
asap.


Applied to dma-mapping-for-next.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland