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([2a01:e0a:f0e:9070:527b:9dff:feef:3874]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-429952b7ce1sm20189382f8f.0.2025.10.28.06.51.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 28 Oct 2025 06:51:30 -0700 (PDT) Message-ID: <15e0d683-e524-44ed-b253-c6221585d9bd@redhat.com> Date: Tue, 28 Oct 2025 14:51:29 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 22/27] hw/arm/smmuv3-accel: Add support for ATS Content-Language: en-US To: Jason Gunthorpe Cc: Nicolin Chen , Shameer Kolothum , qemu-arm@nongnu.org, qemu-devel@nongnu.org, peter.maydell@linaro.org, ddutile@redhat.com, berrange@redhat.com, nathanc@nvidia.com, mochs@nvidia.com, smostafa@google.com, wangzhou1@hisilicon.com, jiangkunkun@huawei.com, jonathan.cameron@huawei.com, zhangfei.gao@linaro.org, zhenzhong.duan@intel.com, yi.l.liu@intel.com, shameerkolothum@gmail.com References: <20250929133643.38961-1-skolothumtho@nvidia.com> <20250929133643.38961-23-skolothumtho@nvidia.com> <26f4d9b2-75be-4913-bb60-01e647a7ec83@redhat.com> <25d22f06-69e2-4954-9bd9-f73f899fc114@redhat.com> <20251028121625.GF1018328@nvidia.com> <9748e922-057b-4e7c-ad6b-b83f5591290a@redhat.com> <20251028134148.GH1018328@nvidia.com> From: Eric Auger In-Reply-To: <20251028134148.GH1018328@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=eric.auger@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: eric.auger@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 10/28/25 2:41 PM, Jason Gunthorpe wrote: > On Tue, Oct 28, 2025 at 02:21:32PM +0100, Eric Auger wrote: >> >> On 10/28/25 1:16 PM, Jason Gunthorpe wrote: >>> On Mon, Oct 27, 2025 at 10:53:10AM -0700, Nicolin Chen wrote: >>> >>>> Hmm, that sounds a legit reason, though adding the ATS support to >>>> the emulated SMMUv3 isn't seemingly a small effort... >>> What is "emulated ATS" anyhow? >> I guess it means implementing ATS translation requests and capability to >> send ATS invalidations. something like: >> >> https://lore.kernel.org/all/20250628180226.133285-1-clement.mathieu--drif@eviden.com/ > Why would you even want this? The cover letter didn't explain what the > point was. well I am just concerned about exposing ATS support to emulated EPs while we actually do not support it. > > qemu emulating two levels of IOTLB caching in software, with a > software page table walk?? Why?? About the actual use case for ATS emulation you'd rather ask the contributor, early SW development, IP development? Eric > > Jason >