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([2603:80a0:3900:aa00:abba:f323:b886:8886]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-6d582b792dbsm4199062eaf.11.2026.09.25.17.33.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 25 Sep 2026 17:33:11 -0700 (PDT) Message-ID: Date: Fri, 25 Sep 2026 19:33:08 -0500 Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/2] iommu/amd: Add PerfOpt IOMMU performance optimization support To: Jason Gunthorpe , Mario Limonciello Cc: Joerg Roedel , Alex Deucher , amd-gfx@lists.freedesktop.org, Suravee Suthikulpanit , Vasant Hegde , Will Deacon , Robin Murphy , "open list:AMD IOMMU (AMD-VI)" , Jatin Kataria , Boqun Feng , "Derek J . Clark" References: <20260908041207.38113-1-mario.limonciello@amd.com> <20260908041207.38113-2-mario.limonciello@amd.com> <20260924225018.GB16465@ziepe.ca> <20260925122848.GD163130@ziepe.ca> <4560d7d3-4d67-457d-bcd7-2176bd850bd4@amd.com> <20260925223928.GE163130@ziepe.ca> Content-Language: en-US From: Mario Limonciello Autocrypt: addr=superm1@gmail.com; keydata= xsFNBFfXIYYBEADlBpwn46Os2kqQK7xm12wq3dTQBBjV0/MNTYzuhcKMXXTSco0SGJTaeNCd 3YVNxkzcJpNvpRGfjpVSRJkgXB0kdUEf7M+XET9p9jJwVXJKB+IIRhcKxnqujLdWIr6ZDPb4 HkTp186cfSfqUZcwpCHQnmYLrdwPdEoTH6KOqubgjK/MaK7StmSG8zd8/1tJukzz/aF82OGD YOdQXUyoSpWEr525h6BIYJKwQkaWiVJ6/kL0HA1ItTiiAh3rOoVRnC5u3vSg9acakesKeH+Z jw6zg55z/9JXNWdBdl7nkBl9QLz067bJ3Q8H5/CYHxqMQhMNgnlTE/sdR1U/S6Om1Oyv+rkV znjZJrvEKzuUIgtvO7YJc65l/SobIsZ/YW0+sZ/io86P/moADYvO6XspTxn5aYuGAcgCtQBj JR5d6GXbeeiJlBAmCExyi3G92CCtgDHnFH+qnf2LsorzMbG0GmpjKOWxFX8uo4aRQ8mAh01O MBaSoeXoZgnoq70McKUon3OqorXcJwX01R/R1MBwevfEVssJFByLNR2GxjZWE52pGf0f5hqy IA+nBf7lTJzFQhll8ncq4IsuuDT/wXnKWsXk4uYCs+SLT2Q8dTBUqDTsOnWdHL1PxPiZTx5i 4IoQCLQnV4WztrAZrUAR+IpkKjEBzXRBH7GkFV9wqSFqCqeD8QARAQABzSVNYXJpbyBMaW1v bmNpZWxsbyA8c3VwZXJtMUBnbWFpbC5jb20+wsGRBBMBCgA7AhsDBQsJCAcCBhUKCQgLAgQW AgMBAh4BAheAFiEECwtuSU6dXvs5GA2aLRkspiR3AnYFAmZjPBoCGQEACgkQLRkspiR3AnZH bBAAqZt+efxiBsA12x6khw87cLLNwRRaDV9Iw52jCbAcjyXVtRyJwrHuUqHzs4bkHfoKoFOB pwGqmTkOGVslu0KDHYCX0h9V9LwRZFTSxom9b6U9VUVsIKldJT23lQAvogCIilRGgrftIQDX Q0HCHN8S7HlrsRWwEdlrGxM9qMLzKFWLWi+COjPqtM+X8UmQIvhd60XjcmZS8OSkaLlAtKnp 2diTqpmGBsjcCAt9jeYLj4ejzfNiXn7l7xfUbNRPiBSm6YV8eT88+xNUXpH4DdkFOvajjgCm 26/PcgY6Qy6kDhRdfgqODloXVpsYvU+DRo8HH+jfaViMvJQSDubZyqlLUnTqODbiJZ/W+GkF Rdncw8xdZj3zUjI2L2Ksv+BmXY/BwKAHfBkPp21H8fN2/SXu6DO8MUVD00s/i3HLuAkhGvEC CXVYQc5SFJpYv4fIbLvRN5013ZaKP1V4Edkysrp0PJ/W8LyH3rg6nNfoIxG9aQRWh+Vtw5uU JzEwvOYzYmWcYDheq/4Ceq+dW4nqTKtbBAi38ATMjdjWIxK5ZiJu6U6AWZC2yYqBqJWTbFaN ZXf4zLZ/VhnLvF64SdFV1pL6tLONSDNq/2GW9kIvbJqXECQj3Y4wP/bDVyshMbu9MSGbBZSu A2X9MdTJXJlWHks8g98VORHswUzPMzI9msu+sgXOwU0EV9chhgEQAL+mOenrfPyR6irpVJo9 7pkFPdDWKrqyID0cbVHEqIv22uYbwQruZp4bMWbOmKg2ztySapj63RNM09sAe0bHG3eRyaKN M5G5JRCB+wkyiUphAGbvN87Pkbj9uoSdxo/tAwMuWtH8sSgbUzHDD7LC3nk/zP8Nd6ApnXfH HrsHjrTaGDCnS3GwKuvCeR8LsSsUbvEAD9lo/+sRzTzZWtywk8EpiUODTZhEJb3V7lwv1bIy I7RjJ2A8uCeUp/VwoeX8IjWwerUPccY+KGbjlkSvkyvK9uDFmYhj6yEi96RaXsL9Zk9R6CpM 1dILcvmbIKwJ4VxXHos5ewWu6lIvUPMkeE5bbOdS6HZdBP9GF/mv/p3bwiolFfMmjwJ0+WzQ +aFD5iOUpWAdhFQAO3nJAuHi+V831s8SYwCbFfF/usctIau4hbp67pX7HJQ02OPiS9tdnOjh M1v7cELAPrlYhZeS3xvZE74xad6gkBBVmlxplTWu62DMKa4uFS8ogjqPkPILSmPGidH9IaUi irYEmtccwa/8bl8Fv1/bwjpLnUoTvMSy1ALXA2OCITPwJaSbCCD5vAxTEUQA5iVW44ree2ZL OVr9Zb9hCZXXpDfAKqVSRkarpFIdVUIKVfQe/FoMKAhQcvKhhsLqZW9X5+Ki0Y7rOx8Krsnw uvim6xPC42cTJeD/ABEBAAHCwXYEGAEIAAkFAlfXIYYCGwwAIQkQLRkspiR3AnYWIQQLC25J Tp1e+zkYDZotGSymJHcCdq5JD/0dX7zNy15ypllaglQwzQ26y9HqS1PVAcnSaY+T+UJvW6rf ORy234R3C3fwNySfnNPIu6JzaFhRKukZHMH00xnf+BmEM/I+b+vf/ylbC9P1jXpLT07z24jc yDVqFf+kMXujLUW9OWmdOC4o3z2bNHK/CV8Xkyjy1ZTBb9fuDKv/XqCci82oaFtQX87bbW9s /DEUl/QM8yDkB6AKgldaVUyKZTkDdrzh7O6+tFDCyLqoOT2aV4z9nSqRs2ICScq1EtqsVthQ fELqAFu8a7lKerErqxs5mFhMY6C1Nto3G8mJ2z6OaH3L8PiUmV4+kmmKgdpAmsJwgByyFeKY W/gq4L21cEQhYatUAL3H4HtYRork65mZfozhInDTFrd7fD2urr0wMqVooM4YuUSkRJAFzt8Q gYiizU7DfJCHGzARQc7X6yhzw9aZY/JAU0m+eruF1pEJic2A5GYbNo4WHsB6b8B1p8vVEMvX 3XwsNt2vh2ITDGJhmeU/zEbjPTUPIK8dxOskFouBMNjN/Ja67/c9nfBTEr4a/8hzFcjxhfD0 Vvvs8b8qJjVxel7u3Ro2VKr+LOKcqnQdPsSGORvw/Drv9eNtVhSlkibKvlZERJ5LG6Y7vtMj REqplPe2LceRhA/5bvevhGJ3UxsrU4i/gOecHUf1vaXSfrVdK50Nvx/aJvZtmQ== In-Reply-To: <20260925223928.GE163130@ziepe.ca> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 9/25/26 5:39 PM, Jason Gunthorpe wrote: > On Fri, Sep 25, 2026 at 08:11:41AM -0500, Mario Limonciello wrote: >> >> >> On 9/25/26 07:28, Jason Gunthorpe wrote: >>> On Fri, Sep 25, 2026 at 09:20:02AM +0200, Joerg Roedel wrote: >>>> On Thu, Sep 24, 2026 at 07:50:18PM -0300, Jason Gunthorpe wrote: >>>>> Why does the GPU driver have to request this? Why can't the iommu >>>>> driver know that this is a special device that can use this magic fast >>>>> path and then auto set it when identity is asked for? >>>> >>>> This is a layering violation either way. Either the IOMMU driver needs to poke >>>> into device details and their relations or the device driver needs to poke into >>>> IOMMU details. >>> >>> There are no device details, this is just a module option in the gpu >>> driver. >> >> Well the GPU driver has knowledge whether it's a GPU inside of an APU to >> decide if it's valid. That information is part of the discovery table >> setup. > > Where was that in patch 2? amdgpu_device_use_perfopt() > > The right way for this to work is to quirk it through the iommu driver > so it can choose the fast mode, and not involve the GPU driver at > all. Like we've done for every other GPU weirdness. And AMD should be > making this work better by providing ACPI support so the iommu driver > can understand how it should work without inspecting PCI IDs. There is a heuristic that Vasant added recently that we detect APU from the IOMMU driver. We might be able to use that for now. I'll take a look at what an incremental patch looks like on top of iommu/next that I think reworks all these paths the way you want. I should be able to post something next week.