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Peter Anvin" CC: Subject: [PATCH v5 12/20] x86/bugs: Add attack vector controls for retbleed Date: Fri, 9 May 2025 11:28:31 -0500 Message-ID: <20250509162839.3057217-13-david.kaplan@amd.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250509162839.3057217-1-david.kaplan@amd.com> References: <20250509162839.3057217-1-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: SATLEXMB04.amd.com (10.181.40.145) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN3PEPF0000B074:EE_|MW3PR12MB4457:EE_ X-MS-Office365-Filtering-Correlation-Id: d3fc6c9a-b893-4d1c-806b-08dd8f169a91 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|82310400026|36860700013|376014|7416014; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?jhi5z3wR/FGynEqGkzAPPOK6UXDiKIFmYl9mlbwwkIRpJd0ZIMVa8t3Tch4e?= =?us-ascii?Q?9BPEAJ+t7m1nq8m44iloP6zFAugWkX4+A/Qqsibpn8u+jLMQJ4jNZwDPUTPZ?= =?us-ascii?Q?/b4LKyhpkTXQnROekWqq0vmJ+/RiT1BV0mujW1UuTRwgL90es5A2mzqE/GmH?= =?us-ascii?Q?UWq9oO6qcnXq1OmxGhM3i2oaiw1BaFqjRJwm4p1YqTvs65k7hzMvVkrP8rKr?= =?us-ascii?Q?RTtS5+I6AV9+9TZt/zUZADWxz7jA6rdEwr4xOoqq15+nIcRzes5jSzU9/EdN?= =?us-ascii?Q?BLDYCatDVcJd6vvegDyIXxrW0t3REbYgtXfUVsKEKSux2xTZxdhSzNsSoxTv?= =?us-ascii?Q?e7Ry9lb/u95SPjAUlXE8dsfiHs2oUWpksrmKtTgnvtmmsTVt4+8vhYyZeyfq?= =?us-ascii?Q?Ln2WmupzpCcWVfBWh9t+vpyTKKbLfzhR97DjTvrf2eLcANZO6zMsv/YNyeMH?= =?us-ascii?Q?oX/WSH8/RN79G9e/zVm31+k9LIL3eHrtrpUK+pi6W1Wf8cCDkMUuheT5huQF?= =?us-ascii?Q?j9tqWajw5ZsVuY7wE6eBO0EGzw+sv7zVE9JKBX+NYBL6DffVmJcSsy6T6+tw?= =?us-ascii?Q?+abBTogFf9u+m5ctor/SWLE/GH0X8z64pegYxoZW0sAZRV5Aasr4f96+Y9f7?= =?us-ascii?Q?Pbfl4WtM+jxhc+jXOsxO1BohWQVFj0Q/PLScGaOerV86fcpBDzOV29+u+ius?= =?us-ascii?Q?JPNijO8ZbgZSTv6/qpw9lLamQkhiW8n5EY+JnRFFulZOe246NQXRKQkh4Wjt?= =?us-ascii?Q?6NIC03rM9MymNPqJ83vmDZusRp/Jr3jPvsrfzczTEOUL6697PnWfnHj/ZcF9?= =?us-ascii?Q?vRLltfiUVGnbDoYZ9dTUaMFHaXzWkZes1RobOemvhO7b0rF8XyqahwaElq5f?= =?us-ascii?Q?qjocIs2+dHKRZNswDMOb+cDCgflXWSwiKrfvL9ijXWEaN4lQ1spn1Mkzo41+?= =?us-ascii?Q?LIpdTQCEmNaPdJvYaofYUknKGv68uwy6wkVVyUsJpsMf36+DkTXTxbf8qMI4?= =?us-ascii?Q?GJ1YFQsPau0rEHqOz/focgZuOMf7SKk8T5hJavKO9m8VVThKEZSdQ5zlLeGd?= =?us-ascii?Q?NG/z0bjDdutUK/ZQUhZ1OkLwPLiDAUs05CKobzelrYDUcePWhuR+DaQkKYWi?= =?us-ascii?Q?T3XKiB9wuBW3KeYcmzaUyxypA+PFE0/3QtWb2dDzGGqWwm9OKTbS9or8rwTA?= =?us-ascii?Q?PhEi2dRHRq12pUnLZWJKj6/BrIYo1C/7nqSrs+KPF9bwlEP1FQvrL7EXH4kt?= =?us-ascii?Q?+XrIqugPhZhFpkPdBKNw1E5yUt4Qo+bYhWoo/+grzxBa12xaoaInWR60I5Y/?= =?us-ascii?Q?YflXjSgHRPNBJVWJVaF/wXrgipjrhKnr1otl8GpdNwtZyq5nOi9K6qvJT0RD?= =?us-ascii?Q?e/Nx3hjQLxBbfYi1Ur3f/tB/m8iPLSCh09S7gR7PBaUY99DmoGjB3xvU1pYj?= =?us-ascii?Q?sHiaZYy9muRIGvX4q63pUY6VLc5IQtkIVcb8Rrd3XAtZN3ZV/xvVNFOJb+Ma?= =?us-ascii?Q?KBSMreeyCJBVOX4Oz7CJAprywg4spnm/Zd8Q?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:SATLEXMB04.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(1800799024)(82310400026)(36860700013)(376014)(7416014);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 May 2025 16:29:00.1336 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: d3fc6c9a-b893-4d1c-806b-08dd8f169a91 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=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BN3PEPF0000B074.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW3PR12MB4457 Content-Type: text/plain; charset="utf-8" Use attack vector controls to determine if retbleed mitigation is required. Disable SMT if cross-thread protection is desired and STIBP is not available. Signed-off-by: David Kaplan --- arch/x86/kernel/cpu/bugs.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index ad68130707c2..160dcaa18b04 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1251,7 +1251,7 @@ early_param("retbleed", retbleed_parse_cmdline); =20 static void __init retbleed_select_mitigation(void) { - if (!boot_cpu_has_bug(X86_BUG_RETBLEED) || cpu_mitigations_off()) { + if (!boot_cpu_has_bug(X86_BUG_RETBLEED)) { retbleed_mitigation =3D RETBLEED_MITIGATION_NONE; return; } @@ -1288,6 +1288,11 @@ static void __init retbleed_select_mitigation(void) if (retbleed_mitigation !=3D RETBLEED_MITIGATION_AUTO) return; =20 + if (!should_mitigate_vuln(X86_BUG_RETBLEED)) { + retbleed_mitigation =3D RETBLEED_MITIGATION_NONE; + return; + } + /* Intel mitigation selected in retbleed_update_mitigation() */ if (boot_cpu_data.x86_vendor =3D=3D X86_VENDOR_AMD || boot_cpu_data.x86_vendor =3D=3D X86_VENDOR_HYGON) { @@ -1303,7 +1308,7 @@ static void __init retbleed_select_mitigation(void) =20 static void __init retbleed_update_mitigation(void) { - if (!boot_cpu_has_bug(X86_BUG_RETBLEED) || cpu_mitigations_off()) + if (!boot_cpu_has_bug(X86_BUG_RETBLEED)) return; =20 if (retbleed_mitigation =3D=3D RETBLEED_MITIGATION_NONE) @@ -1401,7 +1406,7 @@ static void __init retbleed_apply_mitigation(void) } =20 if (mitigate_smt && !boot_cpu_has(X86_FEATURE_STIBP) && - (retbleed_nosmt || cpu_mitigations_auto_nosmt())) + (retbleed_nosmt || smt_mitigations =3D=3D SMT_MITIGATIONS_ON)) cpu_smt_disable(false); } =20 --=20 2.34.1