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Peter Anvin" CC: Subject: [PATCH v6 14/21] x86/bugs: Add attack vector controls for BHI Date: Mon, 7 Jul 2025 13:33:09 -0500 Message-ID: <20250707183316.1349127-15-david.kaplan@amd.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250707183316.1349127-1-david.kaplan@amd.com> References: <20250707183316.1349127-1-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: MWH0EPF000989E9:EE_|MN0PR12MB5740:EE_ X-MS-Office365-Filtering-Correlation-Id: 82e0203d-c88a-43c6-cb89-08ddbd84cc4b X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|36860700013|376014|7416014|82310400026; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?cSd9CpLXUOJHxVDqun394cLz2sA3/knd2dQPHN4l+gzQIAi5BHGX0aVOZ+mh?= =?us-ascii?Q?B0ldvN73N1Y2apOgGZ9JmkSBvmJBaNnvyIv0GCkpbRSnemOIY9RdDHPYXZJ8?= =?us-ascii?Q?xVwpmvriOGCXMibpzlD7hQzW/nJgBnDzH1zoChqOEPmcbVxL9ZY6wphyT7Kp?= =?us-ascii?Q?iGAV4FsRbkStHwvx0z+WuSMaBrb8+DA4OivbXZi4331DY9R4xgYvM4bbArj8?= =?us-ascii?Q?lpcvU8ldFYrNbMPW+T4X7G89M7u59oWC90wboIK9pEA52hQ/W7EHIBk0dxtq?= =?us-ascii?Q?mC7Kilrv+r/ssFDHQVp8/wGmkNsX72PkC+zToLg8AWU/OnYdcdA4DHXwWuI3?= =?us-ascii?Q?UU7+XqeMWlfpoztn4pnOQgCpSfGO93VcmABkFpKmC9UjdTrjAk353ozAvcdI?= =?us-ascii?Q?TwfiAobpRGGVHnWTpMKGSrQh128IAgXuLAYe2MAdfQtB5hFsHhJrC6FmXPcu?= =?us-ascii?Q?xLx02RMCFRQ6AMtxP7lMRu/eGnlS26tkKcPM34o1laSTxElzWT7LGt2USdOq?= =?us-ascii?Q?2eWwNlKgCvdYhvUjlIIMlWobWXeRli0HaA/eYQ2Pc8kZMWmeNnuafWEb0vUJ?= =?us-ascii?Q?QUJIzuz6M+39wXoLXi8yAz8bUxN0eQUPLvJr9a/q/z/Rin09Zl3ILOibPA1p?= =?us-ascii?Q?1Rb2wVCD0E5rhy2KdgJeyJa4sQ0Hk2vpKzRRDz1oFQswt/ZySazjcnZgvDen?= =?us-ascii?Q?7QR/oKkm0Nlv1+W7QX+2b/DJB54s0JYWMFW8MvlwJzDCCzaZDqPo53voeS9u?= =?us-ascii?Q?6+V3e8Jiwm5K1PRwaAN6jiU0TILYoAnjn/F5owiwnDtErI4Vo18rzJsTTTqH?= =?us-ascii?Q?RJ+b9FpRhscx5fmnxBIEM6CyGu7RmTKyASu0WWRFac+8tuA2JKZsxeW3aolZ?= =?us-ascii?Q?i0M3MFmHIa5bTOzPJca2j0skOjU9jxGSuII9bnAjCbIXsiGN+IVGf58oWJzj?= =?us-ascii?Q?W/6XEXOoSCe/ev1VqFcsnPjPOwgY92k1zf+6KGnpuAtir8Mv7cMSBM545zzE?= =?us-ascii?Q?0NEht7/1SrtwKFps4V8tqANObYcjBaRdAusAz1jGl3y14xqWQQ/+VOROdPBm?= =?us-ascii?Q?AueKT3wJU9kQ/Ck7kDbl5f09xxGDsvtd8CaTIGjghavNinsU3dSa5l5TVdxK?= =?us-ascii?Q?5/1qJ8Tmh60A4OIe25KqRkN8D/Aht/zF5R4Zttx1UKYGUq6Ulfiz+suOhihU?= =?us-ascii?Q?JxrKQT5MYwMdW2+eutuaq0TsxkPFscVQQnZlcr9awz5dfQ2hECUgw1iK2T6/?= =?us-ascii?Q?Ts20V97IGiItz+B3tCSyMO9usyK+SYsuOcOpBmUgn4nJbG06WwcuceQRm+Cb?= =?us-ascii?Q?PIUYlDRgJFDJDQv2O5oOFQRKcxdPjiSlDkZ1Ds3gWniKmqnK/tk5TqrNUvXA?= =?us-ascii?Q?naPU217umchQ7H9lE0UowFcmhO+XW9pOqi16Mxl6Qki9nxrBCRQ+YHYwhYu1?= =?us-ascii?Q?VMnt2dLkL/lYEm1tIx07CJQArPgbzbLUyJMTbb3iAawNS7itYJ5rMrOvREG9?= =?us-ascii?Q?SkDHyGlcAbLQ2a/pEpCNvQgliQ5Nlqza5o77?= 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)(36860700013)(376014)(7416014)(82310400026);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Jul 2025 18:33:41.5992 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 82e0203d-c88a-43c6-cb89-08ddbd84cc4b 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: MWH0EPF000989E9.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN0PR12MB5740 Content-Type: text/plain; charset="utf-8" Use attack vector controls to determine if BHI mitigation is required. Signed-off-by: David Kaplan --- arch/x86/kernel/cpu/bugs.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index f331cd70b0b4..adc563443c9d 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -2125,11 +2125,20 @@ early_param("spectre_bhi", spectre_bhi_parse_cmdlin= e); =20 static void __init bhi_select_mitigation(void) { - if (!boot_cpu_has(X86_BUG_BHI) || cpu_mitigations_off()) + if (!boot_cpu_has(X86_BUG_BHI)) bhi_mitigation =3D BHI_MITIGATION_OFF; =20 - if (bhi_mitigation =3D=3D BHI_MITIGATION_AUTO) - bhi_mitigation =3D BHI_MITIGATION_ON; + if (bhi_mitigation !=3D BHI_MITIGATION_AUTO) + return; + + if (cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_HOST)) { + if (cpu_attack_vector_mitigated(CPU_MITIGATE_USER_KERNEL)) + bhi_mitigation =3D BHI_MITIGATION_ON; + else + bhi_mitigation =3D BHI_MITIGATION_VMEXIT_ONLY; + } else { + bhi_mitigation =3D BHI_MITIGATION_OFF; + } } =20 static void __init bhi_update_mitigation(void) --=20 2.34.1