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[159.2.73.22]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-50d4b8da5cbsm20265321cf.31.2026.04.02.05.02.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 02 Apr 2026 05:02:55 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1w8GlC-0000000Bm0s-1xCy; Thu, 02 Apr 2026 09:02:54 -0300 Date: Thu, 2 Apr 2026 09:02:54 -0300 From: Jason Gunthorpe To: Brian Starkey 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, 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, 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, nd@arm.com Subject: Re: [PATCH v5 0/2] dma-buf: heaps: system: add an option to allocate explicitly shared/decrypted memory Message-ID: <20260402120254.GB2551565@ziepe.ca> References: <20260325192352.437608-1-jiri@resnulli.us> <4s75rtsmdfrze4rscbqzyrjyrko7n6sehe7agrngqag2cna5bz@eflmf4kwjocj> 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: <4s75rtsmdfrze4rscbqzyrjyrko7n6sehe7agrngqag2cna5bz@eflmf4kwjocj> On Thu, Apr 02, 2026 at 10:52:34AM +0100, Brian Starkey wrote: > I'm not clear why the heap depends on !CONFIG_HIGHMEM, but I also > don't know anything about SEV/TDX. It is because the CC apis, set_memory_decrypted()/etc are slightly mis-designed. They take in a vaddr to represent the address instead of a phys_addr_t or a page * This means the user has to use page_address() and then the whole thing is incompatible with highmem. Which is fine, highmem and CC are never turned on together. Jason