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[142.162.112.119]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8cd827a1ebbsm505561785a.8.2026.03.10.05.34.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Mar 2026 05:34:05 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1vzwHl-00000005N1Z-0e7z; Tue, 10 Mar 2026 09:34:05 -0300 Date: Tue, 10 Mar 2026 09:34:05 -0300 From: Jason Gunthorpe To: Marek Szyprowski Cc: Leon Romanovsky , Robin Murphy , "Michael S. Tsirkin" , Petr Tesarik , Jonathan Corbet , Shuah Khan , Jason Wang , Xuan Zhuo , Eugenio =?utf-8?B?UMOpcmV6?= , iommu@lists.linux.dev, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, virtualization@lists.linux.dev, linux-rdma@vger.kernel.org Subject: Re: [PATCH 2/3] dma-mapping: Clarify valid conditions for CPU cache line overlap Message-ID: <20260310123405.GR1687929@ziepe.ca> References: <20260307-dma-debug-overlap-v1-2-c034c38872af@nvidia.com> <20260308181920.GH1687929@ziepe.ca> <20260308184902.GR12611@unreal> <20260308230916.GI1687929@ziepe.ca> <20260309090342.GS12611@unreal> <20260309150502.GX12611@unreal> <20260309151356.GN1687929@ziepe.ca> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Mar 10, 2026 at 10:45:38AM +0100, Marek Szyprowski wrote: > Jason is right. Indeed the rdma/uverbs case needs some extension to > ensure that the coherent mapping is used, what is not possible now. This > however doesn't mean that the DMA_ATTR_CPU_CACHE_OVERLAP is not needed > for that use case too. I'm open to accept both. The only question I have > is which name should we use? We already have DMA_ATTR_CPU_CACHE_CLEAN, > while DMA_ATTR_CPU_CACHE_OVERLAP and > DMA_ATTR_DEBUGGING_IGNORE_CACHELINES were proposed here. The last seems > to be most descriptive. If we do DMA_ATTR_REQUIRE_COHERENCE then I imagine it would internally also set DMA_ATTR_DEBUGGING_IGNORE_CACHELINES, but I'd prefer that detail not leak into the callers. Jason