From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3657FC61DD3 for ; Thu, 3 Sep 2026 18:22:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:MIME-Version:In-Reply-To: Content-Type:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=cptW1QHwDr7ociRA0ReHiumlKZ0zB1blA4+y1XqZe+c=; b=3rAxV+4eq2yjGPjJzQc0rw8tt1 a4NJi2f3OlnxpeGzvzT0H3pzNWYvyrHgmkza0CS2opkD8hvqJ1aFkL1qFbOKJ5CNFoWb1NBP1hO8M pwRkGgwQgl0Huge0DY6ZsqYE5E0Y4R3po2zMfmD52b5EWgSSkmhVVBTyiCOtvuvYwecyFX+ncxfiu m7JA915aoUjS5lqp6fD6tPRKJvSgyNPxw61NSTAKnfNadOhOGkG0ONs0R8qoZTZpAoEhQ+tMRkfVv I4ykXUe3FDlI6daWZbH6hQnxylOyyukSYi7CMfuZe7rc5ESUgoTUp/ZMfeqxBlbSKviK1QPbFzQMB GwWHg/lA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x2C4l-00000000MDr-0PSj; Thu, 03 Sep 2026 18:22:15 +0000 Received: from mail-eastusazon11011056.outbound.protection.outlook.com ([52.101.52.56] helo=BL2PR02CU003.outbound.protection.outlook.com) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x2C4i-00000000MDO-3K7n for linux-arm-kernel@lists.infradead.org; Thu, 03 Sep 2026 18:22:14 +0000 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=MbHpNHtMt53FasVxblWQ8WiHqSpb6UKsstsmM3Ff43G4w6s4XjGOzPHBdAHrfMid+njYIzJBCVutm/l45ACYU6j+4JkRi5x7cQoHdH+EqCtRyo2APBuqfuZxuvHvY/RwSyuDPHZvM/3WYCa80mHkxnnBAs1hKyxH+yc3JY6/lrKpICeG6vJM3uTd3sAaSrGjYkZQ5q1NeDY0/sgfvZDJdhel7IgKJQXXVEA/6nX4sqqHST/IC9+gMHt+2wdtqrtX+mKyr6kq89lP/Wp380p8QzMYZTPV6nPibaO5c11e8W+JfrVYCto+0HQ/IZzFEUDkzpWG6XdED+G58xi90ETyGQ== 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=cptW1QHwDr7ociRA0ReHiumlKZ0zB1blA4+y1XqZe+c=; b=QV2x3TFn0w7miOz77WAyTJzVGpsaBpem6Z5OwEZXQggeQvEhzI02paAZJ8bxdI3Bn6sXsnnU7r2WkzIrV6VueAnCsfVlY45h6jtO4uha3+It6nFUcNEptZo78J6HeAlGnbG40GnOjL5A8liWfCe/sFeQAWgIwkoZ9gc6/dzeqncqtOM6p6RP/wB2/CjURHraadr8KYEJSTFQKgvZK1qAKYQmc9BSSfHcBuNQ2kVuZB3qdXxPKqBCuSnhOeEOafIRA4qJvaZmXMVFvXZNc6Ck4w64+DWF/LtwHl9Z3uJF/rbtm7BR/YqJumy1xOnvGlHM2C42UTg4n2Ijbd0ZFTpNvA== 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=cptW1QHwDr7ociRA0ReHiumlKZ0zB1blA4+y1XqZe+c=; b=EO/ErnT67Knu8P3w7VpQgf9qDUKd8gma6FhM7QXXeov6Jmfp3RXFvIvXQfvKxE6Yfwor9q+4A3t6zDVUDniMgOQ7VrXcmOFacikPE1BlJM6H2ENtfRXv4sVtLN9qSEsUJz1jJyWjMgS2ViFpAGLli5eKnnTN/7dO40lJO/CSSwPRRnJSSHcgYSweu90OR+PREKOEZhKkD9Wi5cwNVAqOxcmPMr3WSzuvNXG8nLnjEl5pOmC8u2Oh9tPyhTLDpuG7c/SnDmJx+Z8o3ZZ2BDcfljublITyz3i2upZM0Dc4oarn5GiUDtcaCwKE0pAcWT+KiHREoo4HY/riXNqlkvZSIQ== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from LV8PR12MB9620.namprd12.prod.outlook.com (2603:10b6:408:2a1::19) by SN7PR12MB7812.namprd12.prod.outlook.com (2603:10b6:806:329::18) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.360.13; Thu, 3 Sep 2026 18:21:53 +0000 Received: from LV8PR12MB9620.namprd12.prod.outlook.com ([fe80::299d:f5e0:3550:1528]) by LV8PR12MB9620.namprd12.prod.outlook.com ([fe80::299d:f5e0:3550:1528%4]) with mapi id 15.21.0360.008; Thu, 3 Sep 2026 18:21:53 +0000 Date: Thu, 3 Sep 2026 15:21:52 -0300 From: Jason Gunthorpe To: Sudeep Holla Cc: "Aneesh Kumar K.V" , linux-coco@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Catalin Marinas , Greg KH , Jeremy Linton , Jonathan Cameron , Lorenzo Pieralisi , Mark Rutland , Will Deacon , Steven Price , Suzuki K Poulose , Andre Przywara Subject: Re: [PATCH v9 1/7] firmware: smccc: Add an Arm SMCCC bus Message-ID: <20260903182152.GN4157646@nvidia.com> References: <20260805063255.1638614-1-aneesh.kumar@kernel.org> <20260805063255.1638614-2-aneesh.kumar@kernel.org> <178794567779.4159892.8785590655735217125.b4-review@b4> <20260903125718.GI4157646@nvidia.com> <20260903154626.GL4157646@nvidia.com> <20260903-nonchalant-capable-parrot-539c8b@sudeepholla> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260903-nonchalant-capable-parrot-539c8b@sudeepholla> X-ClientProxiedBy: YT4P288CA0084.CANP288.PROD.OUTLOOK.COM (2603:10b6:b01:d0::18) To LV8PR12MB9620.namprd12.prod.outlook.com (2603:10b6:408:2a1::19) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: LV8PR12MB9620:EE_|SN7PR12MB7812:EE_ X-MS-Office365-Filtering-Correlation-Id: 11f3b6b6-b6e0-49d0-4ff0-08df09e83aa0 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|376014|1800799024|23010399003|366016|10067099003|56012099006|11063799006|5023799004|4143699003|3023799007|22082099003|18002099003|6133799003; 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:LV8PR12MB9620.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(7416014)(376014)(1800799024)(23010399003)(366016)(10067099003)(56012099006)(11063799006)(5023799004)(4143699003)(3023799007)(22082099003)(18002099003)(6133799003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?Y4h4O/pLgnFIiMxbx7pUb0vZfuEl97n9LVEYaja4n3+OUoT4AcxyDLmZB+se?= =?us-ascii?Q?gepl+Huvzq9D4y96GbS81KgewMN3YAWed8wJE4RMGePVkVtC1lBEO++UymI6?= =?us-ascii?Q?2e/mknYWZyk/IiZiE06F3iekmdNTrErTIJHJVEwp8jtvn2gJe+m7W/QoRPGK?= =?us-ascii?Q?QWqEfC8qTsdqSN0NEjMRXTOXUol1lJoa1UcgBa1K0b0gdXeHnkdqY9787bJm?= =?us-ascii?Q?tsEh2WWPkm+B5Es4R6mmClZAATuKHXpxxiO9pV90YtVDe4oMIXw9LLOiTWhC?= =?us-ascii?Q?pztYypJjIXxWcyeq56l5EDqNjT5EsHOz7eW4eJAjK1Hy89jfzbuhw2G7+i4D?= =?us-ascii?Q?cvPTOaf2npf0zYSQAAW2wOv7fMC4XO43djwOxXMbGDJOFEW3Ba/FutF6R6eN?= =?us-ascii?Q?VVCx+iJlBJQ779H7YzHUNXuN/emIlwJjwyR1Hqtp5EG9JdzZ1HsQoSWU72jg?= =?us-ascii?Q?hY1fkZ8P46pvumpEjMe6rJ7WraWU7z62eN60MozB2lxrFy9TGbRL/XwHZmF1?= =?us-ascii?Q?ozSRfiUzA1pVyKk3paZDHRCQ6DKP4hPlFiCwrhCr+5Bd4Ii4NyObmBlFRKbf?= =?us-ascii?Q?xn8oe7//rxdojfjWlndiV10Gx6UcuL1GKBfPqbBo/7LBp8wPe94iaN2WjYYM?= =?us-ascii?Q?n9F/rTTIo5nKy6s1BZp+EVnGqMK407uFOGrlbkRIFF9VOLNENcRKYdE2Z2jM?= =?us-ascii?Q?aavpWAQ8iyNeaCgbyh65u1yNkfgcEYAWWY0txnW+f1tJ3M6p+HduzLZUNwXJ?= =?us-ascii?Q?0xLkSm+RI1rHwnDW8QpRhkozg2ET6z8cNTnHUznh5nA3ufykFgEKHNIaxIXo?= =?us-ascii?Q?3WOesdmh8h4qp0L4eOgbMsuvZocAOi1aAbiHx4kCAm+YpN0VO7lh2apswN5V?= =?us-ascii?Q?mM4WA8kKuJ4Ap+hXKcXZbA/sLlqEq1ZE7PUHvPQA6wijHgBbQ87SVea/yEoX?= =?us-ascii?Q?vQbJltVIhLquvaNmg6OH8OqW7iwwEcI0sITXpluh2GQSu1a4C4UCUltqfQ1X?= =?us-ascii?Q?l97Xjl3IkflMVcRa+bzL5RmEt5fSu7pjh1tvBahVRJvQgojxrDEuoTKCXW1X?= =?us-ascii?Q?+Ga3yRtZ+HQSfszCUeGoMfORdT9cOT+LkG6idhN36NL5NACQGrI1zlFCBFL+?= =?us-ascii?Q?tdSCmyoUQ58R3QVKhO9J65R/a5n1nZGW9EDRi24d8QnXlIVzOvC2Vlss7qak?= =?us-ascii?Q?sCDNadhfjZ4Fu/oyjZY+MIRbQzSHsfH8ewKSb41LcZlnxQgp3HBWRC6wJ0Uk?= =?us-ascii?Q?hvb3w7uS9iPztcu7djLJcgLBZma3EFxdzA+/kS+WtFJy4hmmfubLq7+agJ2d?= =?us-ascii?Q?viUlyxk1DYDoeXXMwodudHhZVqEl/XfQqSlkGELYQecyF8l7lO0OIglXR1Vn?= =?us-ascii?Q?FGlazc6QitQYCJPHIk0cFcedeaDISabyrfYoy9UQyLVOOp0Hyywddg8SfNxe?= =?us-ascii?Q?c1cXAywu/T6x5sicc/GsIamWN17nfRm43KJM5VyyOMoVIJoeLjg7au3eriQ1?= =?us-ascii?Q?yym0zUaEKr9BVEYCtEha3RmlsJGHowO7F6/ZxBNIwuTBDgTI77+QjZm3MuL5?= =?us-ascii?Q?SkcOu7fqTQDKHN/u91WgRbBZr8Wlz22lKM2436eGxi4lCfDE1CqmsF2OyJJS?= =?us-ascii?Q?+cy+9wRc8k+kChhv3e0Rvz6vjgbap/gG8kQ2kmiBJCdUyKuV+rxGxdtPuAfA?= =?us-ascii?Q?6SuX8T/vn/SGQ/TX1W+2FRkefi6LaGtl2nbJC/jw5Q0mhz45?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 11f3b6b6-b6e0-49d0-4ff0-08df09e83aa0 X-MS-Exchange-CrossTenant-AuthSource: LV8PR12MB9620.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Sep 2026 18:21:53.5046 (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: 7qmQU//Hl7wQDf5dOUl6V1kY9kYqTrYAjD8h+IQrVJId2aNOuiTdJU5ryYm0cge9 X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN7PR12MB7812 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260903_112212_832435_310CA75F X-CRM114-Status: GOOD ( 20.41 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Sep 03, 2026 at 05:18:16PM +0100, Sudeep Holla wrote: > Oh yes, we need this whatever you term as "duplication". I would argue > against terming it as duplications as if you look at the various SMCCC > based specification, we have zero consistency in how the VERSION command > is expected to work. Okay, then that pretty much settles it. Nothing to do > > Missing a check means FW upgrades might become Linux breaking. > > Are you referring to the SMCCC bus code or RSI in particular above. I don't > see any issue with SMCCC bus code check as that is the least we can do and > must not change with future versions of the firmware as well. Just in general, SMCCC drivers have to do something smart with the version. Like, is this OK: #define ARM_SMCCC_TRNG_MIN_VERSION 0x10000UL static inline bool smccc_probe_trng(void) { struct arm_smccc_res res; arm_smccc_1_1_invoke(ARM_SMCCC_TRNG_VERSION, &res); if ((s32)res.a0 < 0) return false; return res.a0 >= ARM_SMCCC_TRNG_MIN_VERSION; } ? It means you can never publish a version 2 that is ABI breaking because linux doesn't check for that. Was that ARM's intention with the version API? It's basically a completely pointless check that doesn't effectively do anything. My broader, more general point is that if SMCC is being made into a discoverable bus, that's great, but it would be even better if ARM could find a way to progmatically enumerate all the ABIs present on the SMCC interface to populate the bus. That would necessarily include some consistent treatment of versioning for consistent interoperability. > If lower is also set at v3.0, then I would argue it is firmware upgrade > issue expecting old kernel with old RSI version supported to work. If > that returns v2.0, the driver must work IIUC. Aneesh, hopefully I got this > right ? There was many long conversations about this and I think the conclusion was RSI will broadly not use versions for any kind of ABI control. It is too coarse to really work in the real world and we must have strong forward/backwards interoperability inside VMs forever. Jason