From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from BN1PR04CU002.outbound.protection.outlook.com (mail-eastus2azon11010016.outbound.protection.outlook.com [52.101.56.16]) (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 C64694562AA for ; Tue, 4 Aug 2026 23:57:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.56.16 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785887834; cv=fail; b=soF2UsWJYsHHuHRiwSvB1CK9T1jDuPieLVbOtivfxMWP8neRYYAyYxlpy9jgZrUsvFGjN72dpdjDe53n3wrRkg1WCJDzg76723KqfSIxLGLc/fnpdIKaIMtLJnamai63RNbpzCD4ySU+k5/08wIGWcxGCpzayyEztuO2WcfeoHQ= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785887834; c=relaxed/simple; bh=/8iN0dLNJB7B/w+c8fG69zzj17gK4F5thO/PJvNkufk=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=a6NY/106rKhu4voVQ9jtevIolvm+tFuvcow6Cg2gNw9zjebjuYZmJ+ww3I+8ZZCTYAjAgpzIu04PRSuxYDvO9mGM+Ybxao3RtU4nBzSb7fkGZVuYUr3sAisPAn0JTj5h1TLOXgV0L0S3WOs6YaVkoF1SULPrb7mm59e7MisuSfE= 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=BuhDbx92; arc=fail smtp.client-ip=52.101.56.16 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="BuhDbx92" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=VEbpPh+oLzJBNvfztUsBbMu9F/jCOAkDF/s42ShFuTRp41s8JpZ6bdemONtBmcKg9EyvOG/JNeTewHJXh7/aA4vqQNxDHswsp8RnYESKgjNDL0VYpOtz8Foyt6W+JMgiO/EiOTQmZQDpgiyk+aBDtw/rU+r2/+ZzHv7BHK1U8Mmw3CzsnMDJExomTeUZ7CSMjiRtl6Rf1s9qjKs8KwuNVPSrpk9Ph+hyXQ3RBWM2glSuR7HT2POwiCNpcGXPYezsxGtEVS+jfd/U5f8odNhNN0cCKH/8LO9KdYAdnMEs8Z4aRndRgm9ZZWb0Iufavmqhy+RDovOH2s7a06WN4gjQkA== 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=7V5fvAywgkHl+XvZQLyCv4+sFuU7e7OEOgDaSYD2JW8=; b=p8kBV4DylLF5nXf+EgW3iI8vIF1qtS3fHJLXrlga+cTiVRYM1zejOzWe/H6JDdgR7tpkffVGWl5GuDolXraxpHKKgl+8oSvAA3GvR4z+ZTA4XPf22LA0Y5iYsG25Mgp0PsJ5kxVt5WgOLg0JEPcpegVTkQY7CnqakmTx+LYTGiM66QC3WiJ0fTaolu1DTwnk5uKEl9TZ0FlnHHB2Zj6A/JkMUmXMRr8ho5RruDcHXENcD3JKvfxDcFYP0/snjwXy0mN9BUhYogL+0jr69wOF+o49yPguprElr4xiNi2GpidIihldszHIlV/+gykH/b3dSQ+LkCxFFo6+InVXPF7ocw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=vger.kernel.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=7V5fvAywgkHl+XvZQLyCv4+sFuU7e7OEOgDaSYD2JW8=; b=BuhDbx92mR/SjTS1TZS9KfAafjjsrTAH6LfFRCYwu244bH6d2EiptatGVHzMTh8aOgSAEWepmc0UPKwA/iq5HKELzzYYSKAw0TjisdYv1YH+AuNaKVUysQP6t0m8yAr0uADO7T1srZ2wzCkvvuNBn6omYZpFs5RGJEazaHhs7vs= Received: from BL1PR13CA0228.namprd13.prod.outlook.com (2603:10b6:208:2bf::23) by DS7PR12MB8420.namprd12.prod.outlook.com (2603:10b6:8:e9::14) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.270.18; Tue, 4 Aug 2026 23:57:07 +0000 Received: from BL6PEPF00020E62.namprd04.prod.outlook.com (2603:10b6:208:2bf:cafe::92) by BL1PR13CA0228.outlook.office365.com (2603:10b6:208:2bf::23) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.21.292.16 via Frontend Transport; Tue, 4 Aug 2026 23:57:07 +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 BL6PEPF00020E62.mail.protection.outlook.com (10.167.249.23) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.292.8 via Frontend Transport; Tue, 4 Aug 2026 23:57:06 +0000 Received: from dryer.amd.com (10.180.168.240) 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 15.2.2562.41; Tue, 4 Aug 2026 18:57:05 -0500 From: Kim Phillips To: , , , CC: Sean Christopherson , Paolo Bonzini , K Prateek Nayak , "Nikunj A Dadhania" , Tom Lendacky , "Michael Roth" , Borislav Petkov , Borislav Petkov , Naveen Rao , David Kaplan , Pawan Gupta , "Dave Hansen" , Kim Phillips , Subject: [PATCH v4 03/10] cpu/bugs: Fall back to AutoIBRS when retpoline unavailable on SNP CPUs Date: Tue, 4 Aug 2026 18:56:04 -0500 Message-ID: <20260804235611.4053375-4-kim.phillips@amd.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260804235611.4053375-1-kim.phillips@amd.com> References: <20260804235611.4053375-1-kim.phillips@amd.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: satlexmb07.amd.com (10.181.42.216) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL6PEPF00020E62:EE_|DS7PR12MB8420:EE_ X-MS-Office365-Filtering-Correlation-Id: 3c2eb501-88ee-4501-f1cd-08def2841714 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|23010399003|36860700016|82310400026|1800799024|10067099003|5023799004|56012099006|22082099003|18002099003|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:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(376014)(7416014)(23010399003)(36860700016)(82310400026)(1800799024)(10067099003)(5023799004)(56012099006)(22082099003)(18002099003)(11063799006);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: cRg0fu1J+RDGqFK6RENAhdtuCbUuacMlP9Ye4Mn8sv6WXmEWv8VYxOVDxYgLTgt2hMgERkFwdi1DIOu9HKZBUEIvhqpy7wW2PcmVFTxLfdoPvRzZ+m2tZ4BBrYZINIGAmTNFfBdJ+s9ZKsCTxj8x6a+aSxgQG7INecSb97Kac2SxkvsUwrUJvOq01YezhYYXR56Frbt/JD6iXMwsK1Tv83K4CZwWULFJbT5eXIiPvAl/qZgD3Au4aOgZMn4sE1GyuXH+kDvyez6FdI0wOhW+LgU3eXfOIBNU4bAnJtqPplj1sH1UPuhdlEBO6Weumn32UTvNG1DLyMdAL7v2t/mmoD6ctW/6tXWrX9rpjf3qrmol14n6Pa2zQPwgH7wNx1V7AdPT0qMT16LJpIpWveAj5Bmacyvnl9UT700JITXbOztqfKt1P8d5sldRsVRTDtXq X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Aug 2026 23:57:06.9710 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 3c2eb501-88ee-4501-f1cd-08def2841714 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: BL6PEPF00020E62.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR12MB8420 When the kernel is compiled without CONFIG_MITIGATION_RETPOLINE, spectre_v2_select_retpoline() returns SPECTRE_V2_NONE, leaving SNP hosts with AutoIBRS completely unmitigated against Spectre v2 in the default/auto case. Since SNP CPUs have AutoIBRS available, fall back to SPECTRE_V2_EIBRS rather than leaving the system unmitigated. The preceding commit already enables AutoIBRS (and sets X86_FEATURE_IBRS_ENHANCED) on SNP parts, so no additional feature-bit fixup is needed here; only the mitigation selection changes when retpoline is unavailable. Fixes: acaa4b5c4c85 ("x86/speculation: Do not enable Automatic IBRS if SEV-SNP is enabled") Cc: stable@kernel.org Signed-off-by: Kim Phillips Assisted-by: ClaudeCode:claude-opus-4-7 --- arch/x86/kernel/cpu/bugs.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index a813a98ac5bd..6a036b509f0b 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -2204,6 +2204,15 @@ static void __init spectre_v2_select_mitigation(void) } spectre_v2_enabled = spectre_v2_select_retpoline(); + /* + * If retpoline is unavailable (e.g. built without + * CONFIG_MITIGATION_RETPOLINE), fall back to eIBRS on + * AutoIBRS-capable parts rather than leaving SNP hosts + * unmitigated. + */ + if (spectre_v2_enabled == SPECTRE_V2_NONE && + boot_cpu_has(X86_FEATURE_AUTOIBRS)) + spectre_v2_enabled = SPECTRE_V2_EIBRS; break; case SPECTRE_V2_CMD_RETPOLINE_LFENCE: -- 2.43.0