From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from PH0PR06CU001.outbound.protection.outlook.com (mail-westus3azon11011033.outbound.protection.outlook.com [40.107.208.33]) (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 57565332623; Wed, 24 Jun 2026 19:08:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.107.208.33 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782328099; cv=fail; b=oa8fZ5g2bMSG5j3hAqLtThzkZJuyoS2/fFZMLKPRdS0pEoXweYk6qPyMg1djT+omiGRUeB5TICgOolo6CEDw01Ouh9FuXxi9Kq6AZ5ApsyHppWwtH1Qi2z0JB50kdkAP3R47Bnk/cdYU/MSIuexSrXo2lin+4U/kwje9wBPFt+s= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782328099; c=relaxed/simple; bh=ey5vnOdOTahA8felPdL1kdnnlWrBlGW7G3VRxcREeYE=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=h1vedproHiWyNLM08Fd7f4zMkWxX5LCFQVe0j6TR0IFQ7t7mvR9Laoztg6ZV9LUWbhIb77z1MpYhahUcVcdX0YO9Qs3vckiXfTxY53E8e8kG6asAiOlHSLATa0VR+VBcClan2a+XdMZxdpTe0F6xYDEHzLymYIdmenC7KJYZt/g= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com; spf=fail smtp.mailfrom=amd.com; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b=Jm+K7p36; arc=fail smtp.client-ip=40.107.208.33 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=amd.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b="Jm+K7p36" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=sreKwBBY8UMUsSWNKBMQ5dBfgR+e/ExJtswVbOaaP05LEv08SQzvTeKp+hcvu/cab6e2Z8qNBTkb670BkjMlBY3HlT2FqymUsrfXKlduFAV2jMKbTTzaQYwOIiU/4Ksq7EOj/w+7OetGczeutyhCC4zmKCPmyGBQBnxXhjOHP9c2amz4J163qB2EG5Y80AXjGn2swwbI/4dGu6XeJtWqZWPqwSfiUBM82No0YWHsoA0KAFedRu8ASBTc6J7MDlEjRf5b2Cr8NLfoZB3scmSWlIAtacaG5Y0rFG4hYl6tT1C5+KIsVHWmp0pNLRncZJySrgZmfBNodntP79wE8ZoADw== 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=DGNY86/42mEBVmKplgXKLFmafYRBaaF5XYNcq5av0n4=; b=TzC5cFIs1PVxYpNVs3dCR9qY84CLzSXzOZPr1EN9DwlF049nSApuptf0qdTVEDvUXXkdCrarp3SNjfRJYnz1ecvHtMkKG+bleIYV/UfWWHHbb/qKn66w6OY7OKHxPXW4cDVJ9tnkkVnmmXZQtwHzX0Ms5xVMmLJNuwkSDqtrL0+GN7wKK1daHw97AwTdSF/baKzHmk5W7oFR5qnAIgI6434lQEwMSutdUzuWju36IXCi1OyKdfZ/sRPEPXL8i11z5dGrD1zKVtyc9hJpiz3todJwu17XM7GvAMBllvbAQMvBrNm4g2vHFDCfRNPrUbmiQ/XsIMIX7TND4x/B464m4w== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=alien8.de smtp.mailfrom=amd.com; dmarc=pass (p=quarantine sp=quarantine pct=100) action=none header.from=amd.com; dkim=none (message not signed); arc=none (0) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=DGNY86/42mEBVmKplgXKLFmafYRBaaF5XYNcq5av0n4=; b=Jm+K7p36AukpPwRVcDWX3KK+ZoEcnuHgBRLxHOX0j4vc/WK/9ehThoN1SHLArUvw7pvlJNZiJ9mTXzfsSpJlYcNvjTBr/bf2ZTxIkkQZnmLlyPqzOr/aKbl7i1Wm5saOHBWsZ6pGDM/80lPUNQlcykmyhE6zwHqCm+4fz5mqTOU= Received: from SJ0PR03CA0095.namprd03.prod.outlook.com (2603:10b6:a03:333::10) by CH1PPFD8936FA16.namprd12.prod.outlook.com (2603:10b6:61f:fc00::624) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.139.18; Wed, 24 Jun 2026 19:08:14 +0000 Received: from MWH0EPF000C6191.namprd02.prod.outlook.com (2603:10b6:a03:333:cafe::4e) by SJ0PR03CA0095.outlook.office365.com (2603:10b6:a03:333::10) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.21.139.16 via Frontend Transport; Wed, 24 Jun 2026 19:08:14 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 165.204.84.17) smtp.mailfrom=amd.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=amd.com; Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=satlexmb08.amd.com; pr=C Received: from satlexmb08.amd.com (165.204.84.17) by MWH0EPF000C6191.mail.protection.outlook.com (10.167.249.106) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.159.10 via Frontend Transport; Wed, 24 Jun 2026 19:08:13 +0000 Received: from satlexmb10.amd.com (10.181.42.219) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.41; Wed, 24 Jun 2026 14:08:13 -0500 Received: from satlexmb07.amd.com (10.181.42.216) by satlexmb10.amd.com (10.181.42.219) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.41; Wed, 24 Jun 2026 14:08:09 -0500 Received: from [172.29.28.188] (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server id 15.2.2562.41 via Frontend Transport; Wed, 24 Jun 2026 14:08:08 -0500 Message-ID: <4b551319-0a04-47d2-bc57-2f0d4d9923a9@amd.com> Date: Wed, 24 Jun 2026 15:08:08 -0400 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] x86: Avoid divide by 0 in amd_smn_init() To: Borislav Petkov CC: Andrew Cooper , Mario Limonciello , Yazen Ghannam , "Thomas Gleixner" , Ingo Molnar , Dave Hansen , , "H. Peter Anvin" , Penny Zheng , , References: <20260623211904.3674-1-jason.andryuk@amd.com> <20260623213552.GAajr8ONjXFUnuUOE3@fat_crate.local> <48629f88-4b78-424e-a199-d87594c8cb40@amd.com> <20260624155910.GCajv-zguf0GiBxt2F@fat_crate.local> <0500111d-91bf-4105-8de3-af44a113157a@amd.com> <20260624171536.GDajwQuLD9pkLRLpLE@fat_crate.local> Content-Language: en-US From: Jason Andryuk In-Reply-To: <20260624171536.GDajwQuLD9pkLRLpLE@fat_crate.local> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MWH0EPF000C6191:EE_|CH1PPFD8936FA16:EE_ X-MS-Office365-Filtering-Correlation-Id: 6dd20b67-dd5d-4c9a-6976-08ded223f0e2 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|376014|1800799024|23010399003|36860700016|22082099003|18002099003|56012099006|3023799007|4143699003|11063799006; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb08.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(82310400026)(376014)(1800799024)(23010399003)(36860700016)(22082099003)(18002099003)(56012099006)(3023799007)(4143699003)(11063799006);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: GMku83NupxY31yzoqGIDTqIKm74WICrdRh6JlVuRvO4h1v6A56vq/CDsRtbWaew5eWfZAGaX4YZlHg5o+xncN/Q6qsemae/5DqhnoT2Z+buWYdHHRnetjA6PfWHLdVsWaAhPsMWNkvJSL+t8DY+mw/crWxBeQgszNNPRLDz9t5aidgn7g9aTkrjI/adsLUmdHaKiC0DuQSEYdsHAhTGqNWUCW5VDuFaAJyujOulLjTiFKdhe8okAm/9r757TxEJaLtsFpe6RDexNxwDPRkE2hDd+tI6cw9+dKZolQlJ64BACGz5qKxAR3GkvTIN0yiUfca4xFIhtj9eJQmfSrIuom9UeSMsJKhhF98fFN2hoI9m+WnfbwaOVbbo+8gx0TKIt0gVPB4cmVNMpUKAonXbpG3GU+43Xi/Byn0YeboMy2wFS4xYKvIHKw9wJHqi1Zv9q X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Jun 2026 19:08:13.8926 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 6dd20b67-dd5d-4c9a-6976-08ded223f0e2 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb08.amd.com] X-MS-Exchange-CrossTenant-AuthSource: MWH0EPF000C6191.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH1PPFD8936FA16 On 2026-06-24 13:15, Borislav Petkov wrote: > On Wed, Jun 24, 2026 at 12:41:48PM -0400, Jason Andryuk wrote: >> I think this is the issue: >> >> The "root" device search was introduced to support SMN access for Zen >> systems. This device represents a PCIe root complex. It is not the >> same as the "CPU/node" devices found at slots 0x18-0x1F. > > What is that? AI output? It's from the commit message of 40a5f6ffdfc8f8ed0d8c535dfa3733b31c66a88c >> We don't want dom0 to access the "CPU/node" devices. It's the "root" device >> SMN access I am trying to retain. > > I know what you're trying to do - you want to use SMN accesses on dom0. And > I'm trying to figure out a stable detection method on Xen which is future > proof. > >> Many amd_smn_read/write calls have hardcoded node 0, like for amd-pmc. > > Maybe. > > Whatever it is, it needs to be a long-term solution and properly vetted by Xen > folks so that we don't do crazy hacks for Xen's sake everytime. Sure. I think Ingo's suggestion to re-add the check will at least get systems booting again. Then when Xen SMN accesses is sorted out, that can be changed as necessary. Regards, Jason