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Re: [PATCH v4 11/16] dma-mapping: export new dma_*map_phys() interface
- To: Leon Romanovsky <leon@xxxxxxxxxx>
- From: Keith Busch <kbusch@xxxxxxxxxx>
- Date: Tue, 19 Aug 2025 12:22:30 -0600
- Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>, Leon Romanovsky <leonro@xxxxxxxxxx>, Jason Gunthorpe <jgg@xxxxxxxxxx>, Abdiel Janulgue <abdiel.janulgue@xxxxxxxxx>, Alexander Potapenko <glider@xxxxxxxxxx>, Alex Gaynor <alex.gaynor@xxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Christoph Hellwig <hch@xxxxxx>, Danilo Krummrich <dakr@xxxxxxxxxx>, iommu@xxxxxxxxxxxxxxx, Jason Wang <jasowang@xxxxxxxxxx>, Jens Axboe <axboe@xxxxxxxxx>, Joerg Roedel <joro@xxxxxxxxxx>, Jonathan Corbet <corbet@xxxxxxx>, Juergen Gross <jgross@xxxxxxxx>, kasan-dev@xxxxxxxxxxxxxxxx, linux-block@xxxxxxxxxxxxxxx, linux-doc@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, linux-mm@xxxxxxxxx, linux-nvme@xxxxxxxxxxxxxxxxxxx, linuxppc-dev@xxxxxxxxxxxxxxxx, linux-trace-kernel@xxxxxxxxxxxxxxx, Madhavan Srinivasan <maddy@xxxxxxxxxxxxx>, Masami Hiramatsu <mhiramat@xxxxxxxxxx>, Michael Ellerman <mpe@xxxxxxxxxxxxxx>, "Michael S. Tsirkin" <mst@xxxxxxxxxx>, Miguel Ojeda <ojeda@xxxxxxxxxx>, Robin Murphy <robin.murphy@xxxxxxx>, rust-for-linux@xxxxxxxxxxxxxxx, Sagi Grimberg <sagi@xxxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Steven Rostedt <rostedt@xxxxxxxxxxx>, virtualization@xxxxxxxxxxxxxxx, Will Deacon <will@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Tue, 19 Aug 2025 18:22:39 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On Tue, Aug 19, 2025 at 08:36:55PM +0300, Leon Romanovsky wrote:
> From: Leon Romanovsky <leonro@xxxxxxxxxx>
>
> Introduce new DMA mapping functions dma_map_phys() and dma_unmap_phys()
> that operate directly on physical addresses instead of page+offset
> parameters. This provides a more efficient interface for drivers that
> already have physical addresses available.
>
> The new functions are implemented as the primary mapping layer, with
> the existing dma_map_page_attrs()/dma_map_resource() and
> dma_unmap_page_attrs()/dma_unmap_resource() functions converted to simple
> wrappers around the phys-based implementations.
>
> In case dma_map_page_attrs(), the struct page is converted to physical
> address with help of page_to_phys() function and dma_map_resource()
> provides physical address as is together with addition of DMA_ATTR_MMIO
> attribute.
>
> The old page-based API is preserved in mapping.c to ensure that existing
> code won't be affected by changing EXPORT_SYMBOL to EXPORT_SYMBOL_GPL
> variant for dma_*map_phys().
Looks good.
Reviewed-by: Keith Busch <kbusch@xxxxxxxxxx>
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