From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from BN1PR04CU002.outbound.protection.outlook.com (mail-eastus2azon11010037.outbound.protection.outlook.com [52.101.56.37]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4918837C10C; Thu, 9 Apr 2026 10:34:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.56.37 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775730846; cv=fail; b=ov+hk2pAOFNFlMufw5IZl3qTDWh5XhPSZFp/Lt2spcswmaGr1UJptRafkIM39n0/ab5fzesYNtLYI+mq/EgCYvHyLWTXXoN/7y/QWgkSCAaF4O96/G+sNbGMWIcZAasFHrFielpq4E8iaB9HdVp4K5s1frA5vcKex0FY208oBsk= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775730846; c=relaxed/simple; bh=7svNhhXBEOxd5UE68N2GSixIE/MdF1FMWM9N6dP6zuU=; h=Date:From:To:Cc:Subject:Message-ID:References:Content-Type: Content-Disposition:In-Reply-To:MIME-Version; b=haCb3VCOGKvIksIJWOY4hT56lTK9orDUkmfo0kbEoIgI7Dcyn9PLfZs2ap5Fg6kM3YuIk6C/NMsiZCPe1s7nzR5VOrlLBMYuZ0t3hyXhX+QHEcamlPbYU2Y5tleZjYWbrp6501y0SwU2kL+iKJvyWugHzcrt79DgGYq8WxmAZ3g= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com; spf=fail smtp.mailfrom=nvidia.com; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b=ROs+sTC1; arc=fail smtp.client-ip=52.101.56.37 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=nvidia.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=nvidia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=Nvidia.com header.i=@Nvidia.com header.b="ROs+sTC1" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=Aj41T+MasDm+PckCkTO2FVWfziedezJk/EATK2jgQbJmM8IFy5jnT7vu9VJeM/vkkRFCEdUOY4L3j/M91+Q4ppusUlLVT7XfPwNqnjVS0d8B78Sdkpc+SBf7+G+bRb79YN+W+rv4pLSvWHHkfZo0zhGPYFbMLjKqohfWbk1Fk3Yewri6A3FM9xWMCykrRNxgoQ1C9l3xkBRbtKyIFWcjd4ShO9Z0DnZR+FI/hlWuPjB6ivXqn91diXBylDfmJtfsBCvTOSGwVs/gfQG+QTHUD42HImSl95J+U8bOrFGlxnjU8w1feJzGBTaKu0qV7N4t2vUBd1vIkmBVFQdVMp2FjQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=IQVke9bmsoOzK9pErtklZWx+xoiN/1OTuXeK2LhlYG0=; b=Dluaf5j8f3hn0igmoB4uOGiJeodUCxJeaM78vCQr0316bQPhNvKf90ErsqMC7s2CeNuRc8efHi0RGjQ9Ctp3zl0nsfaBKX8fexIF/CnLKig+XFEsX3O94RSf9XdwlGWst4BGBSzLb6yuEFunCZXCoYHpWW+iC3HaxnrEQWk7DX9763YtmdGfsaCc8QJI88P/xaiakKi4s1cQumlhNH42RGEMQrGtJElvOxYQ3yJa19SlrEyVw1VWJcdLk6mScQsulro7zYT23T4enqfAfOutD+Y7V/82aPDQ+F7Kxs71ytfY2SxA1LNrOaW1Fo33y8aNoRoW5m6R8uTVk1q9ODDXsA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=nvidia.com; dmarc=pass action=none header.from=nvidia.com; dkim=pass header.d=nvidia.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=IQVke9bmsoOzK9pErtklZWx+xoiN/1OTuXeK2LhlYG0=; b=ROs+sTC1xDLMzFebUuPc3dU9C42/1CBdzqZp5h9/KcFGKPhemkjP6TkdcGW1FZIZ9U9uHQEkL/6jXwrgHh1q3h5folDx916Fda2QkDA+uKeiGzRFlR9fcH9hd5zPJomkyLKfS8HERouiZrMIhF7dgnexdeMNmtmevJFlKZBoOYkcAtiOPFeNZz0JXKj1sfOO6Aj3Ek6Hm1gBuh09xFfES51ItfM650MOIAcGeSilHsIHSHTlVuDe1ZjroAKCoj6zwVq5/AnUgudKS6OlaLquxqleo+cygfJ9InwZdEhFWKDBmjICMmGknyFXMr9qI4T3mJnZGLCb/UcD0nDc1fL9QQ== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from DS0PR12MB6486.namprd12.prod.outlook.com (2603:10b6:8:c5::21) by MW6PR12MB8999.namprd12.prod.outlook.com (2603:10b6:303:247::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9769.17; Thu, 9 Apr 2026 10:34:00 +0000 Received: from DS0PR12MB6486.namprd12.prod.outlook.com ([fe80::88a9:f314:c95f:8b33]) by DS0PR12MB6486.namprd12.prod.outlook.com ([fe80::88a9:f314:c95f:8b33%4]) with mapi id 15.20.9769.014; Thu, 9 Apr 2026 10:33:59 +0000 Date: Thu, 9 Apr 2026 06:33:57 -0400 From: Joel Fernandes To: John Hubbard Cc: Joel Fernandes , Eliot Courtney , linux-kernel@vger.kernel.org, Miguel Ojeda , Boqun Feng , Gary Guo , Bjorn Roy Baron , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Dave Airlie , Daniel Almeida , Koen Koning , dri-devel@lists.freedesktop.org, rust-for-linux@vger.kernel.org, Nikola Djukic , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Jonathan Corbet , Alex Deucher , Christian Koenig , Jani Nikula , Joonas Lahtinen , Vivi Rodrigo , Tvrtko Ursulin , Rui Huang , Matthew Auld , Matthew Brost , Lucas De Marchi , Thomas Hellstrom , Helge Deller , Alex Gaynor , Boqun Feng , Alistair Popple , Timur Tabi , Edwin Peer , Alexandre Courbot , Andrea Righi , Andy Ritger , Zhi Wang , Balbir Singh , Philipp Stanner , Elle Rhumsaa , Alexey Ivanov , linux-doc@vger.kernel.org, amd-gfx@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-fbdev@vger.kernel.org Subject: Re: [PATCH v10 12/21] gpu: nova-core: mm: Add unified page table entry wrapper enums Message-ID: <1775730646.3752.4760@nvidia.com> References: <42dd707f-e23a-4725-8b6f-08ca346b0143@nvidia.com> Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <42dd707f-e23a-4725-8b6f-08ca346b0143@nvidia.com> X-ClientProxiedBy: BL1PR13CA0186.namprd13.prod.outlook.com (2603:10b6:208:2be::11) To DS0PR12MB6486.namprd12.prod.outlook.com (2603:10b6:8:c5::21) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS0PR12MB6486:EE_|MW6PR12MB8999:EE_ X-MS-Office365-Filtering-Correlation-Id: b2538080-24db-47a6-b807-08de9623828b X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|1800799024|376014|7416014|56012099003|22082099003|18002099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DS0PR12MB6486.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(366016)(1800799024)(376014)(7416014)(56012099003)(22082099003)(18002099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?UUhNd2IyMW5yd0N2MmU3VC85d0l4OVlvUWgvZFZKN0VsM1UrUVBFN2g0K0Vp?= =?utf-8?B?VS9yWHVHcWw5b1cyTXg4WVZZZlp5NmFiZW5ZSTRDN0VBcm5QSVc1cklRdmsr?= =?utf-8?B?SHhlN0tsTU4waStyL2ZoRjg3UytBTStPa2VBUVcveVhFeEt2N0U5dTk1cEdp?= =?utf-8?B?WnlwUkxGYXhFcE9UZUNlMkIwMGY2N2NLOWEwZjNNeDFRU0MxYm9oQ0VjeWM1?= =?utf-8?B?dUZmanNMNkladVZCTFVNM3BwQzdVbHBydzBIT0N2ZXRLNmJHa3F3N0NTTUgy?= =?utf-8?B?MEpNd1JrMDlIZUVqdllPU0NLNENEc28rRG1CZTlVSytSaS91ZDY4ZytWTW5W?= =?utf-8?B?WE56U2pqNUlWZHJpZ2NDTGFrc0Y0bWJ0SU9EdzZRZnhhQ3dpa1dzdnVVSzZm?= =?utf-8?B?TVJ6NzRVdFp1MnZCNWFDYW5WU09yTUtHd0JIbkI2UDQrS3FEdHJhZ0hQR0lX?= =?utf-8?B?K3R4cU1aNkRrVm1pdEIrM2sxR2hSWU1ZTGpSUHBvSGVXQ3VWM3JsL2lsaU5o?= =?utf-8?B?OEl5OHAzOG5DbU0wUW9NVG9uaW12SWFqZ2VzTitOMUdtYmpSS1pQdDRIZW9u?= =?utf-8?B?RmxVc0liYzdKOVdLTVMvN2dMMnhEVWJWYWNwYlZvVmkxd0hQeUVneSs1dGtK?= =?utf-8?B?WTBtRllVL1oreVV6c3Y4VFd6SnFPRUJtczBIREIxbVArditPYXY2TGQwSTlU?= =?utf-8?B?M3U0a0FFZlJFRG54SG14QjBDbFVSVHkwWjRJVERxV2laa2Fob3I2TnRrM1U0?= =?utf-8?B?NE5RVFZVZXg5NDdHUWhZOGI0NmJuTTNxRnNDekZTVlh2UXJnWG9VbzNaYkRG?= =?utf-8?B?VFV3NCtaeUVqQ2txOUdYQk5INGdjc0NiOFUxd0xXdjlJUEF0S2lUVTYxdVhO?= =?utf-8?B?Q0JEUVJDSlJDcU0rNVMxRTc2OVhnVHpvTTVLRkNIbDRMdGUzRWh4THovMEJU?= =?utf-8?B?dDZseklNRjVsd09Nd1RQUUlsTStaaFBpSDBkRVhlOGliQmhoY3JobENuVlV2?= =?utf-8?B?NVBXazJmT09wMGhkTkNhdzRVcmFVZXU5ZWNveUgxSFQ0T0lZT2p2WWVuZE1P?= =?utf-8?B?bnZDbUNyeG5GcjcycXFOWURMWXhyNGsxTHNiamlmSjlPSjF5RFpYVkNJTm03?= =?utf-8?B?SzgrdFk5SHVMbUY3RlBsbkg5Z0JjdmFEc3cxZzB5V2VvemYvMDgyenBsZ3Vj?= =?utf-8?B?RjY2Vm40MEpNRmF1Q3d3WDc0Z2hSVVVYTFF1Smt2bE5nS3RkVEZGaXpBUnI5?= =?utf-8?B?Nk9tdnQrUURUeUJUU011UDhiK1dScUsyc0VaSy90dTZ4VEYwK1RQWXpWT2lR?= =?utf-8?B?SGVPYXFRWmVjNUh4WEk3VXpKMm9XQWpOZnd3UmFZNEt5empYMHp2STRUMWEv?= =?utf-8?B?eDVCNU9vZ1ZoMFdzMkRsVlBHZENFMnFZOWh1VmlkOHNxeWFPK3B0cURIV1FQ?= =?utf-8?B?RDZFeUZidm8rTDRMUkViRWIxOUxBMHh3czgrSnBUVlJvMmNoM3Bzbms0eWQr?= =?utf-8?B?TDk2eUcwU1lHUEhtT3JodDNERHdHWk9jcnlQbXVFWTFQZmlReHd6eFpuVlNp?= =?utf-8?B?NG9mRENmSGFTYnB3QkpmZWl5bXJGUEw1MFcxeEJRTFlCWmNxQktyNU9ycUVP?= =?utf-8?B?UUhNRzh3Um9YWW5CZm9VY3ZuclA0WnVwQlVSMy9VZWd4czNqY3RyS3Q4TjlY?= =?utf-8?B?L3lLVnA1N0U1NzNzMWhMSXhYRCtLY2ZJbkFEZEU4cFk1cno3UDAzL3RVK0oz?= =?utf-8?B?SjB3L3FSaGNrYWtXRkRYNGpoWmJSMmtwR1Ivd0hON1pFSTNGTjZCdllTQXpJ?= =?utf-8?B?SUF2VjdaeTI5RlcrYzhMSW5sa0htZDNWRWlremR3YWl0R3JaRHRBM1VpaHkv?= =?utf-8?B?dVoyc09sTDIrMDBUcnpLUzcwb3VKemNDMTdkNHNmUjJGbmZMNFBYOWRsWmZy?= =?utf-8?B?S2IrZGpyZ3NwNGRoaUZDZWVQMjAzRFNuSFl0Ukw2VkhqMEFSTGJLZC9LdGg2?= =?utf-8?B?cWExZGxyNWJDUkh2VVpldk5vTys1YVFoUU11czlMaTZhZXQvS1RMSXo3MENo?= =?utf-8?B?SFI4SmErd2I3ZzFOeXZrc3lYV3k5T0REOGl4bEkrVGx2NzRMYUpxeDloVWR6?= =?utf-8?B?eHIwUExHem5KOVBVdUxjbExMZ0ZpaUtpQUdpZFl3bnBuQ1BsaHh6RnBYbFpY?= =?utf-8?B?cDJCekpncXNzdUZyQWVGdy80QkxRK2VJSmFHOTRCcnZqc1d1QUtkOFpDdVdG?= =?utf-8?B?YlQzc2ZJSHQ1NFQzaU5NVkx4T0R3Mm42dW1WdEcxdlo1Mm9NREYxc1VrRnRK?= =?utf-8?B?aFI2Q3dVWnAxNjZwYVp1STFoYWR1bFcrV3A5a3UxTXZ1NlA2L1ZUdz09?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: b2538080-24db-47a6-b807-08de9623828b X-MS-Exchange-CrossTenant-AuthSource: DS0PR12MB6486.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Apr 2026 10:33:59.4428 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: mk8zZhOumboQNlAZU95U0lf/nA8l2sZPBw2WKjYU/Xl9MtlMf+bCk5zTajDt7NitviWH5TFioEKYfUyhr8ox1w== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW6PR12MB8999 > On Apr 8, 2026, at 7:13 PM, John Hubbard wrote: > > On 4/8/26 9:58 AM, Joel Fernandes wrote: >>> On 4/8/2026 9:26 AM, Eliot Courtney wrote: >>> On Tue Apr 7, 2026 at 10:59 PM JST, Joel Fernandes wrote: >>>> On 4/7/2026 9:42 AM, Eliot Courtney wrote: >>>>> On Tue Apr 7, 2026 at 6:55 AM JST, Joel Fernandes wrote: > ...>> [1]: https://github.com/Edgeworth/linux/commits/review/nova-mm-v10/ >> First, thanks for the effort. I looked through this, its pretty much what I >> had before when I used traits. I don't think it is better to be honest. In >> fact your version is worse, it adds many new types and things like the >> following which I did not need before. > > Hi Joel and all, > > I also looked through Eliot's above attempt carefully, and actually > liked it a lot (sorry! haha): > > * It cleans up the code. The initial working version was readable, but > also had lots of noise on the screen: match statements and pairs of > v2/v3 statements. > > And interestingly, the mmu_version was, in effect, sporadically > implementing a Trait-based approach. But because it is custom, > readers don't benefit as much as they would with Traits, which > tell you immediately how things are structured. > > Joel, I am passionately in agreement with your principles: code must > be readable on the screen. > > In this case, though, Traits make considerably more readable, > especially if one makes the very reasonable assumption that readers are > thoroughly accustomed to dealing with Rust traits. > >> >> To put it mildly, the following suggestion should not be anywhere near my code: >> > > lol I understand, believe me. But this is short and not too bad, really. > >> /// Type-erased MMU-specific [`Vmm`] implementations. > > Type erasure remains a semi-exotic thing, IMHO. As such, another > sentence to elaborate on this would be a nice touch. > >> enum VmmInner { >> /// `Vmm` implementation for MMU v2. >> V2(VmmImpl), >> /// `Vmm` implementation for MMU v3. >> V3(VmmImpl), >> } >> >> /// MMU-specific [`Vmm`] implementation. >> struct VmmImpl { >> >> Seriously, I have to pass on this. :-) >> >> And, you unfortunately seem to have ignored my point about requiring 4 NEW >> traits (Mmu, PteOps, PdeOps, DualPdeOps etc), which I did not need before. >> So you're making the code much much worse than before actually. We don't >> new traits and types pointlessly. > > They are not pointless. > > However! What I think would be nice is: do a new v11 with approximately > this approach, and then we can beat it into being as readable as > possible. Since it is 3 against 1 here, I rest my case :-). I am still in disagreement since I do not see much benefit (that is why I said pointless above). Actually it is not even about readability, that is subjective (and I haven’t heard most people say parametrizing code for the sake of it makes it more readable anyway). It is that the code gen is worse, and the complexity is just moved to a higher level in the code, not removed. So what are we getting out of this really, other than more boiler plate in higher layers of the code that did not exist before? Not performance, not better generated code. Really nothing. See all the data points in my previous reply. Note that if the mmu version threading bothers everyone so much, we can also pass down chipset instead and let the walker deal with determining versioning. Would that be better? But otherwise and since you guys asked, here comes a parameterized v11... ;-). (Coming next week since this week I’m working on IRQ handling). thanks, -- Joel Fernandes