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[47.54.130.67]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8b02ae7df88sm249063966d6.35.2026.04.26.06.05.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 26 Apr 2026 06:05:31 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wGzAx-0000000Egs5-0CBA; Sun, 26 Apr 2026 10:05:31 -0300 Date: Sun, 26 Apr 2026 10:05:31 -0300 From: Jason Gunthorpe To: "Aneesh Kumar K.V" Cc: Jiri Pirko , 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, leon@kernel.org, sean.anderson@linux.dev, ptesarik@suse.com, catalin.marinas@arm.com, 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 v5 1/2] dma-mapping: introduce DMA_ATTR_CC_SHARED for shared memory Message-ID: <20260426130531.GF804026@ziepe.ca> References: <20260325192352.437608-1-jiri@resnulli.us> <20260325192352.437608-2-jiri@resnulli.us> <4qdizkkoeke3cvkcf35upa7p7ick6s654eqlrizmi7ozkw5eze@tnpk2e34xgwl> <20260421121004.GA3611611@ziepe.ca> <20260424225514.GE804026@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: <20260424225514.GE804026@ziepe.ca> > > static inline dma_addr_t dma_direct_map_phys(struct device *dev, > > phys_addr_t phys, size_t size, enum dma_data_direction dir, > > unsigned long attrs, bool flush) > > { > > dma_addr_t dma_addr; > > > > if (is_swiotlb_force_bounce(dev)) { > > if (attrs & (DMA_ATTR_MMIO | DMA_ATTR_REQUIRE_COHERENT)) > > return DMA_MAPPING_ERROR; > > > > return swiotlb_map(dev, phys, size, dir, attrs); > > } > > > > if (attrs & DMA_ATTR_MMIO) { > > dma_addr = phys; > > if (unlikely(!dma_capable(dev, dma_addr, size, false, attrs))) > > goto err_overflow; > > goto dma_mapped; > > I suspect P2P is probably broken on CC because this doesn't make > sense.. Actually, I suppose it is fully broken because it will jump to swiotlb and then should fail. > This should flow into the > phys_to_dma_unencrypted/phys_to_dma_encrypted block as well AFAICT, it > shouldn't just assign phys. Assigning phys to dma on a CC system is > always wrong, right? > > It is is more like > > /* To be updated, callers should specify MMIO | CC_SHARED instead of > * implying it. */ > if (attrs & DMA_ATTR_MMIO) > attrs |= DMA_ATTR_CC_SHARED; So no need for this if, we can go directly to marking the MMIO callers with DMA_ATTR_CC_SHARED once this is fixed for mmio: > if (attrs & DMA_ATTR_CC_SHARED) { > dma_addr = phys_to_dma_unencrypted(dev, phys); > } else { > dma_addr = phys_to_dma_encrypted(dev, phys); > } Jasn