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[142.68.128.5]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6e1afc23080sm61987686d6.54.2025.01.22.08.20.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Jan 2025 08:20:56 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1tadTL-00000003qLW-46Wn; Wed, 22 Jan 2025 12:20:55 -0400 Date: Wed, 22 Jan 2025 12:20:55 -0400 From: Jason Gunthorpe To: Mostafa Saleh Cc: "Tian, Kevin" , "iommu@lists.linux.dev" , "kvmarm@lists.linux.dev" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "catalin.marinas@arm.com" , "will@kernel.org" , "maz@kernel.org" , "oliver.upton@linux.dev" , "joey.gouly@arm.com" , "suzuki.poulose@arm.com" , "yuzenghui@huawei.com" , "robdclark@gmail.com" , "joro@8bytes.org" , "robin.murphy@arm.com" , "jean-philippe@linaro.org" , "nicolinc@nvidia.com" , "vdonnefort@google.com" , "qperret@google.com" , "tabba@google.com" , "danielmentz@google.com" , "tzukui@google.com" Subject: Re: [RFC PATCH v2 00/58] KVM: Arm SMMUv3 driver for pKVM Message-ID: <20250122162055.GV674319@ziepe.ca> References: <20241212180423.1578358-1-smostafa@google.com> <20241212194119.GA4679@ziepe.ca> <20250102201614.GA26854@ziepe.ca> <20250116191455.GC674319@ziepe.ca> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Jan 22, 2025 at 11:04:24AM +0000, Mostafa Saleh wrote: > AFAIK, the most common use cases would be: > - Devices using DMA API because it requires a lot of memory to be > contiguous in IOVA, which is hard to do with identity This is not a feature of the DMA API any driver should rely on .. Are you aware of one that does? > - Devices with security requirements/constraints to be isolated from the > rest of the system, also using DMA API This is real, but again, in a mobile context does this even exist? It isn't like there are external PCIe ports that need securing on a phone? > - VFIO is something we are looking at the moment and have prototyped with > pKVM, and it should be supported soon in Android (only for platform > devices for now) Yes, this makes sense Jason