From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from CH4PR04CU002.outbound.protection.outlook.com (mail-northcentralusazon11013041.outbound.protection.outlook.com [40.107.201.41]) (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 5D739338904; Thu, 5 Feb 2026 06:10:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.107.201.41 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770271826; cv=fail; b=O7EUKH+hY2EkNOJOXYjYHc/Ulr1MnJH0vSN/QvApwBiF29r1ooJxcU8kwcqP2DshyxYdpW0EUA1xI0ErBNLQgVAuZuHrB3OSnZ2kIHO38uOqqBsZ2RJpy4S/zS9WH30h932JemaUyjZfAXfGOnaxcuCSomgkTYLJ6mjsMqkXLAI= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770271826; c=relaxed/simple; bh=PieWIvyYBAxFRG2cS7HP/P5Tu3ksP8CgWXKZwP7QLKA=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=Ikfewr+cbvFm3rCvLYYCUL7wVgeRFs82oV3cpXGYtAlwAuWv5/mnXP5ytQzG96Ri0k7p0nzMpJAb9uT1fGV0poFeBM6wBEESKdBUU4YGfxq550YcrhGY7yDsA+/C+Zg+fIHsN2jDL3Tvsyk0gTAeyt8Re7keq/xI5s9U7NMAcls= 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=P/KxQNBz; arc=fail smtp.client-ip=40.107.201.41 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="P/KxQNBz" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=AswGK79mkVKExtDxuyPsjl9QjMlRzxYzB5gW3yZ3ZAF41zyPMtwZ6kur0g+4Wkda8X/a4pIIQRLGTebwKcXjbU2d8KaRY4aNyj8yYyqcKCj6W66Ck2j0GeBoZaQDT4eXsy9PPzTsqhg/fQMsb/BdilgmHgN3flRRGXNiZ4WEpORz0oQCqZrOOsgzQOmluRj+UIt8W2b9Qsy3/i7daTP4pq1Db/OBDU+zcRCI7TTVZzyUNTB9bAmGdBC1iozy8nYn+ClmORrgYyopfgbaW7efRn3V3T2N8bz9WvdD4g/UWqH+oRpBza+J9aIl3Z+egaTVkG0UsuATut3atC+LjnbM4Q== 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=UFkRX/6fgih4Gm79HvJUBnTnevhl/k34ffUdvyNdjL8=; b=BE8ikvq6a0Mx4MIqMKDA4HofLZuZqZ1vwxYx8l9Cj3rG0uthUQ1Sxqoq2kh09a+g5ZwRYQBsYGk2TnSYHM4WQF2KrTMHIgxr/jVLw9HvOqSMnLBWPb0twKwY0alSDK+95IQ9bynp9XJpKKl3wPdtFwAqTHWSLN4UaVTXqrDUfX0STffrTLTFLfySLLyUVZ6uzkTxMJP8/m4NJOBV3mBBbZwYWh5GYVh6nnv6+xDLjU3QiqlRd88LzgU9cwnySucc3fJvVIyIm90aZOHl6r9BKVUjxUv0kdne1bIkvu7ekKSC+r0gagaV2ysBP705KEGkUhSnmASElDEMhQ/8LzyJ/Q== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=linuxfoundation.org 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=UFkRX/6fgih4Gm79HvJUBnTnevhl/k34ffUdvyNdjL8=; b=P/KxQNBzuXa8Ltm4I4xDa1vHTlzSwtTkuPywR+R2GnH2Zet0c1hnktILENQ9ToflUfLPp3K5jkAStXoPusylXG1IX/xd3np/JMA5Kvymrtos7NmzNhO02Di48MN3K4T3prgpN/zaZrrt8NH9xZ4V48YTa3OBvloDARgkO7KhoP4= Received: from DS7P220CA0006.NAMP220.PROD.OUTLOOK.COM (2603:10b6:8:1ca::10) by SA3PR12MB7903.namprd12.prod.outlook.com (2603:10b6:806:307::12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9587.12; Thu, 5 Feb 2026 06:10:17 +0000 Received: from CY4PEPF0000E9D4.namprd03.prod.outlook.com (2603:10b6:8:1ca:cafe::9) by DS7P220CA0006.outlook.office365.com (2603:10b6:8:1ca::10) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.20.9587.14 via Frontend Transport; Thu, 5 Feb 2026 06:10:20 +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=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by CY4PEPF0000E9D4.mail.protection.outlook.com (10.167.241.139) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9587.10 via Frontend Transport; Thu, 5 Feb 2026 06:10:16 +0000 Received: from satlexmb10.amd.com (10.181.42.219) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.17; Thu, 5 Feb 2026 00:10:16 -0600 Received: from satlexmb08.amd.com (10.181.42.217) 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 15.2.2562.17; Thu, 5 Feb 2026 00:10:16 -0600 Received: from [172.31.177.37] (10.180.168.240) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server id 15.2.2562.17 via Frontend Transport; Thu, 5 Feb 2026 00:10:12 -0600 Message-ID: <59781811-a98b-4289-89e4-58e8247241f8@amd.com> Date: Thu, 5 Feb 2026 11:40:11 +0530 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/fred: Fix early boot failures on SEV-ES/SNP guests To: Greg KH CC: , , , , , , , , , , , , , References: <20260205051030.1225975-1-nikunj@amd.com> <2026020559-igloo-revolver-1442@gregkh> Content-Language: en-US From: "Nikunj A. Dadhania" In-Reply-To: <2026020559-igloo-revolver-1442@gregkh> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CY4PEPF0000E9D4:EE_|SA3PR12MB7903:EE_ X-MS-Office365-Filtering-Correlation-Id: 726e7c6b-459d-4e0c-9804-08de647d3bbc X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700013|82310400026|1800799024|7416014|376014|13003099007; X-Microsoft-Antispam-Message-Info: =?utf-8?B?dEgxR1N1elhMOVNIdDVxNW9IRHU5dFVvbUphNHFTa1ltNFJDSDZPdlpSTk9a?= =?utf-8?B?K0s1b3JnQnE0dE5vR3huRnBCVmhTKzJoRHhBRklZTVB4a2ZnUktsdFBDM0JD?= =?utf-8?B?c3I4VTNIYzFJUStCdTZDc2dkeEpxRnBzc3ErQ0Z1cXZOK1FqbDQ3KzI2V1Y3?= =?utf-8?B?UU5OTWRoS0JWYUZ2dlpCKzdiY2FuaDZNNkVmbnl3dWVSbm05Z3V3Y2xldTJp?= =?utf-8?B?VEUwMU93TjB1eWZFT1ZSdExvN242SnJnaDN5cFJSRklldWY4R0d5RU1IczhS?= =?utf-8?B?SU5QMnhnWnBJNjA4Vi9DeG1GLzhqT2xjcWtETi9KdjNwSGN6L0tKMW55V1JJ?= =?utf-8?B?UW9DRzVEeTR4NSt5eHpHYS9hZ2R0WXM5NXFHcnNUL0hiSUt6OWlqRUl5TWdI?= =?utf-8?B?clVJd1M1NU5uK2tsTmhyK2dZaExhYUlPTnRhdW9LSkNzSTZpUGkrQmY2amZM?= =?utf-8?B?Tzk4Q2VrVGVNTUdseDhZblZFY1FxRXg4bVNDOHhtNWtNK2dnRzd6ck5kR3Vi?= =?utf-8?B?M3pvWGU2SjE3d0NYQXZ3elBkRXRhTHVwTWs3WG1Ka1hub3Fjcjk3NE14VGFB?= =?utf-8?B?S1E2VUs5bE1jTHI3Vlp1T2loVW5kWW40c2I5TCtoUmhFb2RXSHpnZ2MwU1lD?= =?utf-8?B?aWljVlVhRFBZKy9KSSsza09EUzhkUmUvL210d3NiWlYwSTlEM2hjUEVYNmVC?= =?utf-8?B?T2tqT0Q1MmxnalBVQktacnNZYmpPMDZjVGdVK1lvSHlKbmNtelFRazNkUnNN?= =?utf-8?B?VmZaa1I5RGNqNG5saGhIVnd2emkwQTVvU2IzVmZLM0UweDdEbWJ0K3k5REtu?= =?utf-8?B?bkZNVFR6dzcvdWcreXk1WCs0R0ZUVHRtY3daOGpiT2xZVktqaEJ1N01wcE8z?= =?utf-8?B?QUlQUXVWUFc3Rks2em1sVE9qK05uUEZrbVJERkpLcXFmUWNOM2Vxa2dLMjh1?= =?utf-8?B?dWVxQkQzQytxWU5Pc3B5VmFIMEF1RjhmdWtSL2ozL0l4dUxhZkt1VUtvODFK?= =?utf-8?B?UkpwZTNLeEVoS1JhV1h6SEp1b3gwcVBOWlVPcmYrcWVCaHlMOERXMXZYZFo4?= =?utf-8?B?YjBoSE0zd0pXMW1BYlFCQWtkd0c1c2wzMGtDVHhoOWlpSWRMZkFoUXRxNkxF?= =?utf-8?B?bTd5N3JOR0V5R3dmWHVqNzIyVFdiT05IWklBSEFtRVd1TncwZDJja1dIQmk2?= =?utf-8?B?SjcrQXdzWXMzNnM1U3lDYmhrR0JSMHErc04zdDk2REYwWkdFbkhsMFZmWmN3?= =?utf-8?B?Q01SWkdmUHB6SmhpZ3pUQ3Bzd05kbXgrZmR4T1FIbEhGMEM4QjBXMlhBZHBu?= =?utf-8?B?b0dVa0VUeE1LSW14U1NMdVYxaUtRZ1FFUy8wUGpGYnhQSlpxYWR4cHY1NDBS?= =?utf-8?B?WlNUMWlPSnVpa3NtT0FSZzYyRUU5RWtEZTBKQ0tvK3R6S2krQ2NLSTJsTVdi?= =?utf-8?B?R3M2ZHFJM1lvd2h3UGgyb09KUVRuVVVOeGdPYUM1TkpheFdpV2tETDVNaXdz?= =?utf-8?B?OU54MEppblJpZS9WbFB6Mm1RTm5nak9INEhDK0xPRXBibHVHUFdkbzMxV0tS?= =?utf-8?B?NFdZa3ZJYmNNNkRuNllydXdMUy9WOExhRVNlQWtEOWgrL2VxbUFRaXFVeFVy?= =?utf-8?B?MXVvNWNidGpkTmd2aE9jMmZPRi9LczMyV1JPWDZVYmZ0dktTMEV1aE1qUmFz?= =?utf-8?B?eTN6UDllR25zOVgzOVZkQTNXSnlNMHFTOFc1V21ReHJ1RG41ZnA5ZDlvOWF1?= =?utf-8?B?Z29UaWl0Q0NWVjFtOW5PR0dDNEVmMnFydmRjVlZHRnFEU0pMbWRWQzNFOEo0?= =?utf-8?B?VjQ5ZElMdGZKUUFuUHBXYmEyc0RiK2NpSHh4R2Q1UytTRE1aeHB3d0VBVlE2?= =?utf-8?B?R3ZCZ2FGNGMxL2c4VHZxZXl1VkhJVGluVHhoUEluTmpyOTFYdjVQY3BYMFVP?= =?utf-8?B?R3hNVFFUdDV4Z1hPZWs0ODRweDI3WTJZZndhYnhZQUN4MHc2blpvdS82Uks1?= =?utf-8?B?RjdSOHlVdk0vL28wYUo0aGk2SkFJVXgwSXJnWEFkMi96c2RWSkkrZ2Q0Y3dC?= =?utf-8?B?dTdZY1lJSHplWW1xbk95VkNzRm5pRHdPaTV5S3piZTB0dDZZMlU4Yi8xUmNk?= =?utf-8?B?MVNvaHovNGQ0SDRBU0tRU2U1RUtZS0lXZ2h1R01kU1Q5aUR0d2FjbGwzY2xO?= =?utf-8?B?M3RlcGNvbE9UeEhoOVJTZE5lMnFISGVOL1VMYnprcHdTalpJNzdPU2hHMTBn?= =?utf-8?B?aFFEczZtM0FpbVNXK1JWaTNMQWF3PT0=?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(36860700013)(82310400026)(1800799024)(7416014)(376014)(13003099007);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: C/gnirPmwcwvU80CvUNK8bjPMvDSpXt1YOSO9YD4suM6xght/6ScicjMjeaeTJDOUJmrG+kBF4Dv8eTCfrUmI7rLPH9UGDbiBcLvEo7FIC1YD2KsMN+qHtQqe1OPY4gszkeMMHmLXzzPmkcBKswU6sg9U9Eah+LbYTZMrirHXsG1q5rss5c9pM9PEzTO7ohvn6jazWkAjLWt813jPUtbZQvh93fv07yZwZ/SJJ4Zvmua46T0KCAWN65qxrpO8hbdDrG4byrpz/rrjffcfreq8oIJ8XWlK8xg3yGWf/lSBdkyoxmR9ugymh4kyAKVfHZrXPJMbzMS3G9VTpXVwEwbP8NG271CYzcbLrjbGS09QMKG92RFqlOnrpeGGhPPmQOmOYVg4wa6LFrSaWmBR6ROMaNa/wycjELlhEcO0Kv371udSENfIesjKbvO/wjhK6L/ X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 Feb 2026 06:10:16.8196 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 726e7c6b-459d-4e0c-9804-08de647d3bbc 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=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: CY4PEPF0000E9D4.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA3PR12MB7903 On 2/5/2026 11:25 AM, Greg KH wrote: > On Thu, Feb 05, 2026 at 05:10:30AM +0000, Nikunj A Dadhania wrote: >> FRED enabled SEV-ES and SNP guests fail to boot due to the following >> issues in the early boot sequence: >> >> * FRED does not have a #VC exception handler in the dispatch logic >> >> * For secondary CPUs, FRED is enabled before setting up the FRED MSRs, and >> console output triggers a #VC which cannot be handled >> >> * Early FRED #VC exceptions should use boot_ghcb until per-CPU GHCBs are >> initialized >> >> Fix these issues to ensure SEV-ES/SNP guests can handle #VC exceptions >> correctly during early boot when FRED is enabled. >> >> Fixes: 14619d912b65 ("x86/fred: FRED entry/exit and dispatch code") >> Cc: stable@vger.kernel.org # 6.9+ >> Signed-off-by: Nikunj A Dadhania >> --- >> >> Reason to add stable tag: >> >> With FRED support for SVM here >> https://lore.kernel.org/kvm/20260129063653.3553076-1-shivansh.dhiman@amd.com, >> SVM and SEV guests running 6.9 and later kernels will support FRED. >> However, *SEV-ES and SNP guests cannot support FRED* and will fail to boot >> with the following error: >> >> [ 0.005144] Using GB pages for direct mapping >> [ 0.008402] Initialize FRED on CPU0 >> qemu-system-x86_64: cpus are not resettable, terminating >> >> Three problems were identified as detailed in the commit message above and >> is fixed with this patch. >> >> I would like the patch to be backported to the LTS kernels (6.12 and 6.18) to >> ensure SEV-ES and SNP guests running these stable kernel versions can boot >> with FRED enabled on FRED-enabled hypervisors. > > That sounds like new hardware support, if you really want that, why not > just use newer kernel versions with this fix in it? Obviously no one is > running those kernels on that hardware today, so this isn't a regression :) Fair point. However, the situation is a bit nuanced: FRED hardware is available now, and users running current stable kernels as guests will encounter boot failures when the hypervisor is updated to support FRED. While not a traditional regression, it creates a compatibility gap where stable guest kernels cannot run on updated hypervisors. Other option would be to disable FRED for SEV-ES and SNP guest in stable kernel. Regards Nikunj