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Peter Anvin" CC: Subject: [PATCH v6 15/21] x86/bugs: Add attack vector controls for spectre_v2 Date: Mon, 7 Jul 2025 13:33:10 -0500 Message-ID: <20250707183316.1349127-16-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: MWH0EPF000989E8:EE_|LV3PR12MB9329:EE_ X-MS-Office365-Filtering-Correlation-Id: 0a92b7c5-c761-449d-edf0-08ddbd84ccc9 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|7416014|376014|36860700013|1800799024; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?sAybhEgX6FuWNWn1/pqMuwqcyxBwtAVWPZYn/Zjo3P/IFWtraprKmrvzOFJk?= =?us-ascii?Q?A1ncjjBpq2DsRGkoIVjMeq38ZZ3pDjWm7sVRkYKgtxGwYBLibhZC3vF+AiKy?= =?us-ascii?Q?8uucWnU949V6YXzRR+m0Kg0EqswX4Ewa++g3WfT9SP7spehJB6FoYjkAxdsr?= =?us-ascii?Q?dsqmoMEX1AicfGrpS0eYAH/1HvkVW7FaHUMWTZRks9EeneSmulSDKDaMMPZa?= =?us-ascii?Q?YZJlltHy0fe8LSE9e7lRv7iu73woP12JjbeZQpOW+WVwIsnsHj8KZ4qlaZj4?= =?us-ascii?Q?u98tYGkZjGS6fPxcJXok+kiHPqqziRNGntYmGlpw894ThgxSLcjrKG8AWZ3u?= =?us-ascii?Q?YTUn9oAwE+qPuTPhOsGdeoPZ2UKMXD8UzngvVX9HA3Wp75Blmc/liNHLLZ22?= =?us-ascii?Q?uWhm6zQMlCwftRMdSLo3oVHh8/ib8slmq1snls4w0lfJOM+1p9Ilsp+ms/AV?= =?us-ascii?Q?4OMRPL/IbugU0dkP/7EqHGJnIHdMGPxTGXmFWVWqAJWukyH7y75xO6a0+5Wc?= =?us-ascii?Q?8+RGR6wHLa+o1lwsqJRjpqs+Bl015FoIAnp7RF/RwCu71WsBOzEwHJwVdyoe?= =?us-ascii?Q?IKUN/xn0uMf+7XL5ay4uk3hOBAk5szWvGNb0GXmZjnICaHUK5tAG3o5/bT3Y?= =?us-ascii?Q?9b3ndqaayPlKx3Ubq1n8mdIMoaFn8UR3P4M3qQypLv1a4V69VQDxvDdfLrgj?= =?us-ascii?Q?DC+zK0B2SPCpJ+i9OFCj02H8NsqhnftXjKQ5HbrKBDYbhfmSRMhHFxUrMale?= =?us-ascii?Q?Z95X5fsasdlJfyQJRP/zXU35Ljqs6P8mnj8SNlKh8UjZEUnVKPGxPuh/5TML?= =?us-ascii?Q?cCG2WGfhs23Y3f9IEMUSlJOn0l61gXVNkGltjEY3W8Z7OEGbU7IK1E+2ekRs?= =?us-ascii?Q?FJ8dKPe7gbEKwDYsOuHwbGWzyAw46IBc4qeWAJ9Z4L8nwo0+nhjf4FsgirpR?= =?us-ascii?Q?V0yDEqlKyxRcMhc09MTAiVvAJzWO4n9CLBnRPAd6fTJx6Yru9nNya0RoGIMn?= =?us-ascii?Q?dkXdC40xJ6lhNs9Op0G+x7Yrxx3/iHL+gu6+Xqq5gj2Q78FPlZW1eN/HD23Z?= =?us-ascii?Q?FvSTuDs09HUl7Zo29ot93XvKY8kza5ksSqVip2qQyR9uwqyTYidrViOtEGjF?= =?us-ascii?Q?5PjkTI+gJ6tmGhrVrcJK7XJY5x0efnFXd46irWZ0xtrZA1CMqzArVGGYw+71?= =?us-ascii?Q?Gc9AonvRn+lpy/6bYNaFTZ7JWlS44DfIYtXI/oY8en2qPqy5GCYsu8d9HGf0?= =?us-ascii?Q?xrRf7t4BFdxzFC1VvL386hMl6vK70LsLP8lpR0Vwf2rAhR43ZD6sEX75wUKO?= =?us-ascii?Q?/auF1kBvSR6iNt6whN2vtEhiJ7Ls8Xj8BLKJF8iXtrPG6h5ogsbcHUrYTMrC?= =?us-ascii?Q?h+cgvWtgxIlm5RLPeKtouGTAJNFZD2yUgPQxzHqt1nXG9L/8ta5jgH/ylxa9?= =?us-ascii?Q?wlwyWzA5bzbyRIbbSYAYIa8F8yp2ldf6Ag2DcOis2dJtHE0XA9yvzcm/BSGb?= =?us-ascii?Q?PmczgBmQVUvxST8cUKnzLO7g5HVaDgn/Q66K?= 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)(82310400026)(7416014)(376014)(36860700013)(1800799024);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Jul 2025 18:33:42.4192 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 0a92b7c5-c761-449d-edf0-08ddbd84ccc9 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: MWH0EPF000989E8.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: LV3PR12MB9329 Content-Type: text/plain; charset="utf-8" Use attack vector controls to determine if spectre_v2 mitigation is required. Signed-off-by: David Kaplan --- arch/x86/kernel/cpu/bugs.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index adc563443c9d..2168e75bc1ac 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1921,8 +1921,7 @@ static enum spectre_v2_mitigation_cmd __init spectre_= v2_parse_cmdline(void) int ret, i; =20 cmd =3D IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2) ? SPECTRE_V2_CMD_AUTO := SPECTRE_V2_CMD_NONE; - if (cmdline_find_option_bool(boot_command_line, "nospectre_v2") || - cpu_mitigations_off()) + if (cmdline_find_option_bool(boot_command_line, "nospectre_v2")) return SPECTRE_V2_CMD_NONE; =20 ret =3D cmdline_find_option(boot_command_line, "spectre_v2", arg, sizeof(= arg)); @@ -2194,8 +2193,11 @@ static void __init spectre_v2_select_mitigation(void) case SPECTRE_V2_CMD_NONE: return; =20 - case SPECTRE_V2_CMD_FORCE: case SPECTRE_V2_CMD_AUTO: + if (!should_mitigate_vuln(X86_BUG_SPECTRE_V2)) + break; + fallthrough; + case SPECTRE_V2_CMD_FORCE: if (boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) { spectre_v2_enabled =3D SPECTRE_V2_EIBRS; break; @@ -2249,7 +2251,7 @@ static void __init spectre_v2_update_mitigation(void) } } =20 - if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2) && !cpu_mitigations_off()) + if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2)) pr_info("%s\n", spectre_v2_strings[spectre_v2_enabled]); } =20 --=20 2.34.1