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Tue, 29 Sep 2026 07:58:31 -0700 (PDT) X-Received: by 2002:a05:6214:390a:b0:914:4601:dfd8 with SMTP id 6a1803df08f44-9144601e535mr213689766d6.10.1790693910318; Tue, 29 Sep 2026 07:58:30 -0700 (PDT) Received: from [192.168.0.116] ([124.123.146.251]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-9178d377464sm12112356d6.41.2026.09.29.07.58.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 29 Sep 2026 07:58:29 -0700 (PDT) Message-ID: <4b149801-0846-455f-83aa-a222219d01be@oss.qualcomm.com> Date: Tue, 29 Sep 2026 20:28:22 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v2 0/2] net: wwan: qcom_bam_dmux: Add restricted DMA pool support To: Stephan Gerhold Cc: Stephan Gerhold , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Loic Poulain , Sergey Ryazanov , Johannes Berg , linux-arm-msm@vger.kernel.org, netdev@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Deepak Kumar Singh References: <20260920-qcom-bam-dmux-vmid-ext-v2-0-ef5ca2178378@oss.qualcomm.com> Content-Language: en-US From: Vishnu Santhosh In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTI5MDA1OSBTYWx0ZWRfX/BZeuJ1e63Il W6vDkritQXgNXv9GK5PE0ZZtij3GHUusjrBc9zWU3N4GGCnyjCHGEFlSovEXeSzaONMYmV9q4nm yVrQS2IFtm93MAhwNMGtMBKE90fqd1o3CR957do1sQem1NB941vDwrqh/JB+QkuENNaKTIMw0p1 URD6Dms6NL9mtLQoosxpPyEWR76+lm38bqE4XlJUAaec9Sgq0tiIAL+CPRoIN6D1WZqkSPdtrqT S2f5dhi/x/XeUV798jK1HF3ZjHwuI78JerQvuc+ftpmfhY6pZQakFq1ikxF4QUyDy2Mr4Y6MYT7 kfRYPTUd5isjen7DIpYnWI8nuj2k6LIYl/6b4kqEIUEZQCZBNRCpShxRvFRnOitsSJTr7JN5v3V T3cuApIJDVxvSW70rByWx4bpZAoB3GEDrgmxI5u2GbEBy34Rtxzk17ZylL4bcjWnHQZhdr1jUeP PsFJxabvkYPN8t2l2xg== X-Proofpoint-GUID: HU5L5FTgy_mPf7mrejvc6y0oAJPXuex2 X-Authority-Analysis: v=2.4 cv=VcVir1p9 c=1 sm=1 tr=0 ts=6abbd217 cx=c_pps a=7E5Bxpl4vBhpaufnMqZlrw==:117 a=K/78aEDNEn2Q/Yuv7mVN5Q==:17 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=rJkE3RaqiGZ5pbrm-msn:22 a=VwQbUJbxAAAA:8 a=EUspDBNiAAAA:8 a=uW-ob52F1wccIURrHgMA:9 a=QEXdDO2ut3YA:10 a=pJ04lnu7RYOZP9TFuWaZ:22 X-Proofpoint-ORIG-GUID: HU5L5FTgy_mPf7mrejvc6y0oAJPXuex2 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTI5MDA1OSBTYWx0ZWRfX9GyhNTuQxcM6 zjEkoD+ETJazPqswbdJ/ZlCo+ELF7c8raLPZcdYCbt7lWQX5P6F06Lw7PXkrXUrir7LUQcaiGEt jZNl9RWmHsEn6eoNGN98UJetO+eafZA= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-29_04,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 bulkscore=0 clxscore=1015 suspectscore=0 lowpriorityscore=0 spamscore=0 phishscore=0 malwarescore=0 adultscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609290059 On 29-09-2026 01:44 pm, Stephan Gerhold wrote: > On Mon, Sep 28, 2026 at 04:02:47PM +0530, Vishnu Santhosh wrote: >> On 20-09-2026 08:32 am, Vishnu Santhosh wrote: >>> Some Qualcomm SoCs, such as Shikra, run the modem in a separate security >>> domain with restricted access to system memory. BAM-DMUX DMA mappings >>> and BAM descriptor FIFOs must therefore be constrained to a designated >>> memory region that can be shared with the modem. Accesses outside that >>> region can trigger an XPU violation. >>> >>> Add memory-region and qcom,vmid properties to the BAM-DMUX binding. >>> When qcom,vmid is present, the driver SCM-assigns the entire restricted >>> DMA pool to the local and remote execution environments before requesting >>> the DMA channels. >>> >>> The restricted pool then contains the BAM-DMUX mappings. When the BAM DMA >>> controller references the same pool, its descriptor FIFOs are covered by >>> the assignment as well. >>> >>> A related binding change allows the BAM DMA controller to use the same >>> restricted pool for descriptor FIFO allocations: >>> >>> https://lore.kernel.org/all/20260920-qcom-bam-dma-vmid-ext-v2-1-4dbbff0e57c8@oss.qualcomm.com/ >>> ("dt-bindings: dma: qcom,bam-dma: Allow memory-region property") >>> >>> Signed-off-by: Vishnu Santhosh >>> --- >>> Changes in v2: >>> - Replace the Shikra-specific compatible and coherent RX allocation with >>> memory-region and qcom,vmid properties. >>> - Use a restricted DMA pool for BAM-DMUX mappings and BAM descriptor FIFOs. >>> - SCM-assign the complete pool before requesting the DMA channels. >>> - Validate the remote VMID and restricted DMA pool configuration. >>> - Link to v1: https://lore.kernel.org/r/20260714-qcom-bam-dmux-vmid-ext-v1-0-3f29da7cca76@oss.qualcomm.com >>> >>> --- >>> Vishnu Santhosh (2): >>> dt-bindings: net: qcom,bam-dmux: Add memory-region and qcom,vmid properties >>> net: wwan: qcom_bam_dmux: Assign restricted DMA pool to remote processor >>> >>> .../devicetree/bindings/net/qcom,bam-dmux.yaml | 38 +++++++++ >>> drivers/net/wwan/Kconfig | 1 + >>> drivers/net/wwan/qcom_bam_dmux.c | 95 ++++++++++++++++++++++ >>> 3 files changed, 134 insertions(+) >>> --- >>> base-commit: 8830e65ed46de41f849eefb8ba227d4852c460f6 >>> change-id: 20260714-qcom-bam-dmux-vmid-ext-d9289db310c1 >>> >>> Best regards, >> Hi Stephan, >> >> I followed your suggestion and updated v2 to use the restricted DMA pool. >> >> Please let me know if this approach and the implementation look reasonable and >> meets your expectations. >> > Thanks, the approach looks good to me. You received some comments from > others and Sashiko already, so I will make a more thorough review from > my side once you have addressed (or at least considered) them for v3. > > Thanks, > Stephan Thanks for confirming the approach. I will address the remaining comments as well, so that you can proceed with thorough review. Thanks, Vishnu