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Mon, 28 Sep 2026 03:32:54 -0700 (PDT) X-Received: by 2002:a05:6a00:9095:b0:857:7337:5dba with SMTP id d2e1a72fcca58-8802a7ad603mr6283581b3a.24.1790591574117; Mon, 28 Sep 2026 03:32:54 -0700 (PDT) Received: from [10.218.31.237] ([202.46.22.19]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-87fea88a1a2sm3854645b3a.25.2026.09.28.03.32.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 28 Sep 2026 03:32:53 -0700 (PDT) Message-ID: Date: Mon, 28 Sep 2026 16:02:47 +0530 Precedence: bulk X-Mailing-List: netdev@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 , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Loic Poulain , Sergey Ryazanov , Johannes Berg Cc: 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: <20260920-qcom-bam-dmux-vmid-ext-v2-0-ef5ca2178378@oss.qualcomm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=Sq4Fe/O0 c=1 sm=1 tr=0 ts=6aba4257 cx=c_pps a=rz3CxIlbcmazkYymdCej/Q==:117 a=fChuTYTh2wq5r3m49p7fHw==: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=farQdCg5IzuLFFoMD6QA:9 a=QEXdDO2ut3YA:10 a=bFCP_H2QrGi7Okbo017w:22 X-Proofpoint-GUID: y1mzje9T0WIoU8XpU8Cn8nRtb5FdBtQw X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTI4MDA0MSBTYWx0ZWRfX8/wWKYVNm9A9 E+hMbQJmw+Siv5+s9Mabjb2XCDXWCxCCPZ9CCM15LVJ7GsyqMU973Tj+cM39EWvFwbnBu/Dy66o uxrXvVIyceVzMJ2GiqgipTkqPcufPfWe+Dt0ckviB/3tL64WOxAhaCxW2pFqGl09iaM3WpvgeIG vwzGUsrNWlqsyDX8BMexEwRy4o3+wPaMFtRGK5iOn4ZLUtSrnacMvTO1E1lun34O9ki40Ex2tAl fXMDwsSwv53EQGGSQ0JTbPW0Ga04yukwu3ze+AKZDDAVyOMLzsyu3CYimcAn/Hh/l6ec2xbiTTb aOEib00nPilSLt4ABVDukFsfC32JPfvziazTFNU+Udx2bciE6SsPR+bbI0VipB4k77hn8aOaMS3 xUXjZeS10fOGDhD+xX/NhJ+R/gCLcobDFdKfgvHTVpcjadTfn8wHpGY5jyR0n1onwtUiVcN3boZ Iii/AyIeqKk4vC4oSGw== X-Proofpoint-Spam-Info: AW1haW4tMjYwOTI4MDA0MSBTYWx0ZWRfX77voV5m//sIE UeR2YQNtSbqBwVnCbKwHE6FRdDXi2kAHwHaIDKzKi+gty8Psr6wh0jrAp4g/yHE8mk9poQHz+6v c5ncbfWjG4e0uJR9GhjBN63kHXrkq18= X-Proofpoint-ORIG-GUID: y1mzje9T0WIoU8XpU8Cn8nRtb5FdBtQw 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=2026-09-28_02,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 clxscore=1015 priorityscore=1501 bulkscore=0 malwarescore=0 adultscore=0 phishscore=0 spamscore=0 lowpriorityscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609280041 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, Vishnu