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[217.31.164.171]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a9393138bd5sm174570466b.205.2024.09.25.00.15.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Sep 2024 00:15:06 -0700 (PDT) Date: Wed, 25 Sep 2024 09:15:04 +0200 From: Jens Wiklander To: Dmitry Baryshkov Cc: linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, op-tee@lists.trustedfirmware.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, Olivier Masse , Thierry Reding , Yong Wu , Sumit Semwal , Benjamin Gaignard , Brian Starkey , John Stultz , "T . J . Mercier" , Christian =?utf-8?B?S8O2bmln?= , Sumit Garg , Matthias Brugger , AngeloGioacchino Del Regno , Rob Herring , Krzysztof Kozlowski , Conor Dooley Subject: Re: [RFC PATCH 0/4] Linaro restricted heap Message-ID: <20240925071504.GA3519798@rayden> References: <20240830070351.2855919-1-jens.wiklander@linaro.org> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On Mon, Sep 23, 2024 at 09:33:29AM +0300, Dmitry Baryshkov wrote: > Hi, > > On Fri, Aug 30, 2024 at 09:03:47AM GMT, Jens Wiklander wrote: > > Hi, > > > > This patch set is based on top of Yong Wu's restricted heap patch set [1]. > > It's also a continuation on Olivier's Add dma-buf secure-heap patch set [2]. > > > > The Linaro restricted heap uses genalloc in the kernel to manage the heap > > carvout. This is a difference from the Mediatek restricted heap which > > relies on the secure world to manage the carveout. > > > > I've tried to adress the comments on [2], but [1] introduces changes so I'm > > afraid I've had to skip some comments. > > I know I have raised the same question during LPC (in connection to > Qualcomm's dma-heap implementation). Is there any reason why we are > using generic heaps instead of allocating the dma-bufs on the device > side? > > In your case you already have TEE device, you can use it to allocate and > export dma-bufs, which then get imported by the V4L and DRM drivers. > > I have a feeling (I might be completely wrong here) that by using > generic dma-buf heaps we can easily end up in a situation when the > userspace depends heavily on the actual platform being used (to map the > platform to heap names). I think we should instead depend on the > existing devices (e.g. if there is a TEE device, use an IOCTL to > allocate secured DMA BUF from it, otherwise check for QTEE device, > otherwise check for some other vendor device). That makes sense, it's similar to what we do with TEE_IOC_SHM_ALLOC where we allocate from a carveout reserverd for shared memory with the secure world. It was even based on dma-buf until commit dfd0743f1d9e ("tee: handle lookup of shm with reference count 0"). We should use a new TEE_IOC_*_ALLOC for these new dma-bufs to avoid confusion and to have more freedom when designing the interface. > > The mental experiment to check if the API is correct is really simple: > Can you use exactly the same rootfs on several devices without > any additional tuning (e.g. your QEMU, HiKey, a Mediatek board, Qualcomm > laptop, etc)? No, I don't think so. > > > > > This can be tested on QEMU with the following steps: > > repo init -u https://github.com/jenswi-linaro/manifest.git -m qemu_v8.xml \ > > -b prototype/sdp-v1 > > repo sync -j8 > > cd build > > make toolchains -j4 > > make all -j$(nproc) > > make run-only > > # login and at the prompt: > > xtest --sdp-basic > > > > https://optee.readthedocs.io/en/latest/building/prerequisites.html > > list dependencies needed to build the above. > > > > The tests are pretty basic, mostly checking that a Trusted Application in > > the secure world can access and manipulate the memory. > > - Can we test that the system doesn't crash badly if user provides > non-secured memory to the users which expect a secure buffer? > > - At the same time corresponding entities shouldn't decode data to the > buffers accessible to the rest of the sytem. I'll a few tests along that. Thanks, Jens > > > > > Cheers, > > Jens > > > > [1] https://lore.kernel.org/dri-devel/20240515112308.10171-1-yong.wu@mediatek.com/ > > [2] https://lore.kernel.org/lkml/20220805135330.970-1-olivier.masse@nxp.com/ > > > > Changes since Olivier's post [2]: > > * Based on Yong Wu's post [1] where much of dma-buf handling is done in > > the generic restricted heap > > * Simplifications and cleanup > > * New commit message for "dma-buf: heaps: add Linaro restricted dmabuf heap > > support" > > * Replaced the word "secure" with "restricted" where applicable > > > > Etienne Carriere (1): > > tee: new ioctl to a register tee_shm from a dmabuf file descriptor > > > > Jens Wiklander (2): > > dma-buf: heaps: restricted_heap: add no_map attribute > > dma-buf: heaps: add Linaro restricted dmabuf heap support > > > > Olivier Masse (1): > > dt-bindings: reserved-memory: add linaro,restricted-heap > > > > .../linaro,restricted-heap.yaml | 56 ++++++ > > drivers/dma-buf/heaps/Kconfig | 10 ++ > > drivers/dma-buf/heaps/Makefile | 1 + > > drivers/dma-buf/heaps/restricted_heap.c | 17 +- > > drivers/dma-buf/heaps/restricted_heap.h | 2 + > > .../dma-buf/heaps/restricted_heap_linaro.c | 165 ++++++++++++++++++ > > drivers/tee/tee_core.c | 38 ++++ > > drivers/tee/tee_shm.c | 104 ++++++++++- > > include/linux/tee_drv.h | 11 ++ > > include/uapi/linux/tee.h | 29 +++ > > 10 files changed, 426 insertions(+), 7 deletions(-) > > create mode 100644 Documentation/devicetree/bindings/reserved-memory/linaro,restricted-heap.yaml > > create mode 100644 drivers/dma-buf/heaps/restricted_heap_linaro.c > > > > -- > > 2.34.1 > > > > -- > With best wishes > Dmitry