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Peter Anvin" CC: Subject: [PATCH v3 7/7] x86/bugs: Report correct retbleed mitigation status Date: Mon, 15 Sep 2025 08:47:06 -0500 Message-ID: <20250915134706.3201818-8-david.kaplan@amd.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250915134706.3201818-1-david.kaplan@amd.com> References: <20250915134706.3201818-1-david.kaplan@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: satlexmb08.amd.com (10.181.42.217) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ5PEPF000001D4:EE_|CH2PR12MB4310:EE_ X-MS-Office365-Filtering-Correlation-Id: a79a2ed3-587e-4d45-6782-08ddf45e692e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700013|7416014|376014|1800799024|82310400026; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?9VcuKWXi5ww6A7xxjjVhEiGXnzLzRS7J7DPKGoh1VL4fK5zo8wJJ+/qAnHzq?= =?us-ascii?Q?YHAJqbxZwTUaiommI4RwGv8Gvz5wSRfy5jcbhqzmV5xX0MxtpOE5f5hL2rmv?= =?us-ascii?Q?FpTtBe0eDrULg3Ufpz0kWzz+PY6NfX3EfbaZSzdH8dW/y8j92blV9OjbZJCF?= =?us-ascii?Q?L3slP0G/uE/v0XNOPVdRI2v5t+Td+Ub/effmMYLg+WfbikaXScZDpE/4CS+g?= =?us-ascii?Q?3PLLm1VcXMflq4jbv0yfRNwSHuhgR3Ota7ZDkJ9ZRBa0haeAV2JbgakT/jBJ?= =?us-ascii?Q?/Lyc7tHhDzxpZpA0x/6GqclGxj7pMfj6e4WLWUH5tU+0+jhlvKINs3tensMZ?= =?us-ascii?Q?4HqCcvfSBzdMvnuSOl1GYtvwYAUBSFcyibYj2Y3xjEZCfQYkGGGFvL3dZoZN?= =?us-ascii?Q?rOCNFoBvJJteL2qhRn3ZZ6C0/D9uvwd/CXpSzh+1jDW4jcCWdVthNpmQrVAJ?= =?us-ascii?Q?TPyfAwuP1ZadJsG0cdBqyGeYBdxQwUpQI8cPRsol9decQ5/Dbbv1IqPIYjwV?= =?us-ascii?Q?ElJYXuV1xkZ07mM7W5BNuQU31duYzmOHTlTiG70YgX/u/+24mCJ5JvCkodrl?= =?us-ascii?Q?nEUhz9DYJQAxG87lKPVrKgfBjcDaLOU+gs0UYvuIJk6bAzta8OAr4iWoJie0?= =?us-ascii?Q?KsiuTrin6mRMqapvkvwuhCJDtH6ZFBpnFoIhUTCnwgc3dJdn6rCD8bz1KPQ0?= =?us-ascii?Q?ML4Cabr+nSpv+nhaPTQKPiw15QoIXYBCtzW9axWBi2w/ameXx6O37epg9+Pk?= =?us-ascii?Q?d1nrsFo6GZc1lqf8gkzFxdcrlK2WRl1sUZOEtWW5VrCeKCcjzAua1eyx4zG1?= =?us-ascii?Q?1VQ82M8R9mmFqr9vgAlEmeE6gn9vktPjuGNoyQpeP9pNgfe3drpiYFmvArqi?= =?us-ascii?Q?Xwe5sSbpABwNWS2qh3Ygb8SA5d9jg8uCqCq1VfNISNRBu15elo4XUH14tbpz?= =?us-ascii?Q?36j1cBL078NOAlncR8Cr0Sh+wuCl5jNhVqYubslUIenBt06nrcVIAoj15yQk?= =?us-ascii?Q?AAL0BC2abViCHb90Sv4132ky7tnmYlZVvL+6gxWvRCVlG6sXhkKY68B0Lb1A?= =?us-ascii?Q?a9MfniO5hAXEvblPpPGpuFGYdt1qhuXbna1N/Sf/fRMNcEv8oe9M9UpH7nHc?= =?us-ascii?Q?ydrklEbSIXrJz0Dr1IaxpjCWVp73SdMaXPKIGFW5rxqOuVCqjR3zNIvo3EFK?= =?us-ascii?Q?7mZcfwHRIbgHRB5f8umpbukfUPCJU5gUnvhdcnbEKYe6GqlnqbGnO91eZrRE?= =?us-ascii?Q?DtdTV52WRjEUqGLqFTTm49silXiLREKGPXnMovzlsEg6ucLJBeZXnacKiCrm?= =?us-ascii?Q?htlXOvDOR9RRliDZVo3YgwodOs1wlrqQi3KQrJwzgdBivAt/1XSsTgL0pr6Q?= =?us-ascii?Q?Yrrbr9Vw0Wv1ND4/VcrpAgwrV8LHZuHNBHfsnnfUzpvluaDtIrmll2uh9y1p?= =?us-ascii?Q?Ss+GZ0sdddso7dBv+RMtDDCwNL3dKP11eFW+CnnapUQZ4hDhUgp5cZcSUA1q?= =?us-ascii?Q?KusLPMuBKXLkrnjionRoC2klM2eKgxaKDknJ?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(36860700013)(7416014)(376014)(1800799024)(82310400026);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Sep 2025 13:47:28.3883 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: a79a2ed3-587e-4d45-6782-08ddf45e692e 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: SJ5PEPF000001D4.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH2PR12MB4310 Content-Type: text/plain; charset="utf-8" On Intel CPUs, the default retbleed mitigation is IBRS/eIBRS but this requires that a similar spectre_v2 mitigation is applied. If the user selects a different spectre_v2 mitigation (like spectre_v2=3Dretpoline) a warning is printed but sysfs will still report 'Mitigation: IBRS' or 'Mitigation: Enhanced IBRS'. This is incorrect because retbleed is not mitigated, and IBRS is not actually set. Fix this by choosing RETBLEED_MITIGATION_NONE in this scenario so the kernel correctly reports the system as vulnerable to retbleed. Signed-off-by: David Kaplan --- arch/x86/kernel/cpu/bugs.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 1f3a20f6fac0..45c9605fc5c3 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1462,8 +1462,10 @@ static void __init retbleed_update_mitigation(void) retbleed_mitigation =3D RETBLEED_MITIGATION_EIBRS; break; default: - if (retbleed_mitigation !=3D RETBLEED_MITIGATION_STUFF) + if (retbleed_mitigation !=3D RETBLEED_MITIGATION_STUFF) { pr_err(RETBLEED_INTEL_MSG); + retbleed_mitigation =3D RETBLEED_MITIGATION_NONE; + } } } =20 --=20 2.34.1