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[47.54.130.67]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8ca36086a61sm95500586d6.4.2026.05.19.09.11.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 May 2026 09:11:20 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wPN2O-0000000FGo6-1YPM; Tue, 19 May 2026 13:11:20 -0300 Date: Tue, 19 May 2026 13:11:20 -0300 From: Jason Gunthorpe To: "Aneesh Kumar K.V" Cc: Mostafa Saleh , 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: <20260519161120.GO7702@ziepe.ca> References: <20260519152741.GM7702@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 Tue, May 19, 2026 at 09:35:30PM +0530, Aneesh Kumar K.V wrote: > Yes, that also resulted in simpler and cleaner code. > > swiotlb_tbl_map_single > /* > * If the physical address is encrypted but the device requires > * decrypted DMA, use a decrypted io_tlb_mem and update the > * attributes so the caller knows that a decrypted io_tlb_mem > * was used. > */ > if (!(*attrs & DMA_ATTR_CC_SHARED) && force_dma_unencrypted(dev)) > *attrs |= DMA_ATTR_CC_SHARED; > > if (mem->unencrypted != !!(*attrs & DMA_ATTR_CC_SHARED)) > return (phys_addr_t)DMA_MAPPING_ERROR; Yeah, exactly that is so much clearer now that the mem->unecrypted is tied directly. That logic is reversed though, the incoming ATTR_CC doesn't matter for swiotlb, that is just the source of the memcpy. /* swiotlb pool is incorrect for this device */ if (mem->unencrypted != force_dma_unencrypted(dev)) return (phys_addr_t)DMA_MAPPING_ERROR; /* Force attrs to match the kind of memory in the pool */ if (mem->unencrypted) *attrs |= DMA_ATTR_CC_SHARED; else *attrs &= ~DMA_ATTR_CC_SHARED; Attrs should be forced to whatever memory swiotlb selected. Jason