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[47.54.130.67]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-516456b6856sm165713481cf.7.2026.05.19.07.37.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 May 2026 07:37:48 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wPLZr-0000000F80e-38LO; Tue, 19 May 2026 11:37:47 -0300 Date: Tue, 19 May 2026 11:37:47 -0300 From: Jason Gunthorpe To: Mostafa Saleh Cc: "Aneesh Kumar K.V" , iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev, Robin Murphy , Marek Szyprowski , Will Deacon , Marc Zyngier , Steven Price , Suzuki K Poulose , Catalin Marinas , Jiri Pirko , Petr Tesarik , Alexey Kardashevskiy , Dan Williams , Xu Yilun , linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , x86@kernel.org Subject: Re: [PATCH v4 04/13] dma: swiotlb: track pool encryption state and honor DMA_ATTR_CC_SHARED Message-ID: <20260519143747.GE7702@ziepe.ca> References: <20260519132911.GA7702@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260519_073750_450703_806A9678 X-CRM114-Status: GOOD ( 10.35 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, May 19, 2026 at 02:27:54PM +0000, Mostafa Saleh wrote: > However, as I mentioned to Jason, I think with some tweaks to > force_dma_unencrypted() we can make it work under pKVM for aligned > memory which eliminates some of the bouncing. > I am currently investigating that. force_dma_unencrypted() literally means that memory passed into the DMA API *without* DMA_ATTR_CC_SHARED cannot be DMA'd from. It should not mean anything else. The DMA API should never decrypt passed in memory. You always have to bounce. Jason