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[142.162.112.119]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8cda1fbcd23sm361027485a.1.2026.03.12.05.06.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Mar 2026 05:06:07 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1w0enm-00000006ejP-0ZCe; Thu, 12 Mar 2026 09:06:06 -0300 Date: Thu, 12 Mar 2026 09:06:06 -0300 From: Jason Gunthorpe To: Jiri Pirko Cc: Leon Romanovsky , dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, iommu@lists.linux.dev, linux-media@vger.kernel.org, sumit.semwal@linaro.org, benjamin.gaignard@collabora.com, Brian.Starkey@arm.com, jstultz@google.com, tjmercier@google.com, christian.koenig@amd.com, m.szyprowski@samsung.com, robin.murphy@arm.com, sean.anderson@linux.dev, ptesarik@suse.com, catalin.marinas@arm.com, aneesh.kumar@kernel.org, suzuki.poulose@arm.com, steven.price@arm.com, thomas.lendacky@amd.com, john.allen@amd.com, ashish.kalra@amd.com, suravee.suthikulpanit@amd.com, linux-coco@lists.linux.dev Subject: Re: [PATCH net-next v3 1/2] dma-mapping: introduce DMA_ATTR_CC_DECRYPTED for pre-decrypted memory Message-ID: <20260312120606.GC1469476@ziepe.ca> References: <20260305123641.164164-1-jiri@resnulli.us> <20260305123641.164164-2-jiri@resnulli.us> <20260308101948.GO12611@unreal> <20260309131530.GJ1687929@ziepe.ca> <20260309140233.GW12611@unreal> <20260309151857.GO1687929@ziepe.ca> <20260312003408.GA1469476@ziepe.ca> Precedence: bulk X-Mailing-List: linux-coco@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 Thu, Mar 12, 2026 at 10:03:37AM +0100, Jiri Pirko wrote: > >Alot of device MMIO is decrypted by nature and can't be encrypted, so > >you'd have to use both flags. eg in VFIO we'd want to do this. > > Why both flags? Why MMIO flag is not enough? You still want to hit > "if (attrs & DMA_ATTR_MMIO) {" path, don't you? Because we will eventually have both decrypted and encrypted MMIO. > I mean, CC_DECRYPTED says the memory to be mapped was explicitly > decrypted before the call. MMIO was not explicitly decrypted, it is > decrypted by definition. For me that does not fit the CC_DECRYPTED > semantics. I would say CC_DECRYPTED means that pgprot_decrypted must be used to form a PTE, and !CC_DECRYPTED means that pgprot_encrypted() was used This flag should someday flow down into the vIOMMU driver and set the corresponding C bit the IOPTE (for AMD) exactly as the pgprot does. Less about set_memory_encrypted as that is only for DRAM. Jason