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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Aug 19, 2025 at 08:36:45PM +0300, Leon Romanovsky wrote: > From: Leon Romanovsky > > This patch introduces the DMA_ATTR_MMIO attribute to mark DMA buffers > that reside in memory-mapped I/O (MMIO) regions, such as device BARs > exposed through the host bridge, which are accessible for peer-to-peer > (P2P) DMA. > > This attribute is especially useful for exporting device memory to other > devices for DMA without CPU involvement, and avoids unnecessary or > potentially detrimental CPU cache maintenance calls. > > DMA_ATTR_MMIO is supposed to provide dma_map_resource() functionality > without need to call to special function and perform branching by > the callers. 'branching when processing generic containers like bio_vec by the callers' Many of the existing dma_map_resource() users already know the thing is MMIO and don't have branching.. > Signed-off-by: Leon Romanovsky > --- > Documentation/core-api/dma-attributes.rst | 18 ++++++++++++++++++ > include/linux/dma-mapping.h | 20 ++++++++++++++++++++ > include/trace/events/dma.h | 3 ++- > rust/kernel/dma.rs | 3 +++ > 4 files changed, 43 insertions(+), 1 deletion(-) Reviewed-by: Jason Gunthorpe Jason