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Peter Anvin" CC: Subject: [PATCH v6 18/21] x86/bugs: Add attack vector controls for ITS Date: Mon, 7 Jul 2025 13:33:13 -0500 Message-ID: <20250707183316.1349127-19-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_|BL3PR12MB6570:EE_ X-MS-Office365-Filtering-Correlation-Id: bac2e397-d36d-4171-3568-08ddbd84ce14 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|36860700013|1800799024|7416014|82310400026; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?8zSxi4rv9qkxvr/rtMAitMMUV7TmnhZCf+8cEoIuUd+L7vvAzKJo319UqzQ+?= =?us-ascii?Q?1GDMyY34Auf8Ss+214m+dVl82xYIDb5FCOldr9W/lxTlbQNuVVqOgRpgj+gr?= =?us-ascii?Q?kuwbZoZg5F72w3l6/knDSY9xj0b1T+k8ce55wD/jNqsBeWhtW0UANSjSooij?= =?us-ascii?Q?yxkAkWn1x5GFrzCR886CHTH11ovUGl97eKZ8ws9R5RospqNzTO+qNxG/D6O6?= =?us-ascii?Q?25WrdxEsAtGMtbR8JmzzB+iPniqt4ixx+erxL4Hof12lDpBzGzItiBuasG96?= =?us-ascii?Q?7E8W9KEEXGUCtZsi24yS/We2ph2LKhpogK/Pk9nesGRRefbQAirwdFnHFQrj?= =?us-ascii?Q?R6RhZehN9sGZMUh+elU6t+R2kBr5nvqx3FTnp1LQ+L0uLt0dyY7V2LpTaO5n?= =?us-ascii?Q?bCtV1cX+iAO/HR7ZRi2OjaGiqZv54W2/PLhDScg/mm/Ls2uRNFdwQfCnBJzu?= =?us-ascii?Q?afbwtNoUY17pJLnLbI5azOHz8iTBfYER2rlYuYllzCHjhc16PG2MxHsWOZl/?= =?us-ascii?Q?4pQgKvMMjbXf7UElSwQs/DB1yBT9UL1qwZ2qoHDQCtk+fbR17VxFMji6Q2wU?= =?us-ascii?Q?upXRPvS8hAdzHglZBlbKWlJaHt0aShMdDNHH5QOH/UFm1ZVnUGiX8RmHg9Qz?= =?us-ascii?Q?BB3h0n8PiypQLKXVqYwlXVQe1EdjRIwCokyFJ+KnnbG/NX58b5NhC7PEDyXA?= =?us-ascii?Q?Y5rWjcL2q+r37n2SViwG8kuXx4h4SJxeZzryls2yjv99lH3wslz28ptZ2VRx?= =?us-ascii?Q?ypVrMxFfhw1vI/4thO7GF0mCMlFRnpOpisMuV/nhTzWfCc43cBCB7nykxCYG?= =?us-ascii?Q?IinoUYqLRyifSiTRNpMqk+h40GBs6ZHf5Zf7HwTrJDpMfJrVQ/8Py+7bGwam?= =?us-ascii?Q?FV6o7l7+eB88w/k3tlXSN2vAwsPoFb1jvJr16/gJiPd6lkbtW//GXtVlq6jw?= =?us-ascii?Q?D8TDFFoN1SrsKIMp0FHVt9zZlHW+AhzPCus1uGTkdwrc+TGX4PdrdqG/XwLH?= =?us-ascii?Q?KoerjO5DEfNJVC2XvE6Rmu0F8FW6lWSwRnLRzDaJWuy3jI0ia6NXYH5+k7Kr?= =?us-ascii?Q?mc/uLERUAf+G4Nldyux7o21ELPipFh67VLsNxzdPLlxndgC8v80O+0VGXefb?= =?us-ascii?Q?sNHHi4DSILqpdU8DkEajqT+B3KGSELtRqjVWaim5n7R3eI5n77yDjAG6+FnP?= =?us-ascii?Q?nm9Uu5YCeUMpMMPrtNAbOxDzbOHKthyjJkuX53amVVRqJBXy/5Vk5MAht3Ok?= =?us-ascii?Q?nJGTW2ZJ5apQkuhNqqv6JZYG1MRF40s4FA/GUGKKe4xAKXproWbalhybZsIr?= =?us-ascii?Q?a0w4FluEieLVVt2TZzun3SNFXUCg5JToF5hqMtIJAOa5m+DZZl3IkWjm0KLG?= =?us-ascii?Q?3r9ir+a032vEgf1UYg2t0Ozn1QlA+8+0jOVo56lgZlMw0bhwWANM1KZIW+pa?= =?us-ascii?Q?AdODIcrBioph51FLfFZt/4BrlyBO/P4C91FYZKrbkKgNzrCb8jSmmbFfVKg+?= =?us-ascii?Q?KmzQvQHCrXvELcxpD0ZbgqYA9/aySwG7v99R?= 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)(376014)(36860700013)(1800799024)(7416014)(82310400026);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Jul 2025 18:33:44.5892 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: bac2e397-d36d-4171-3568-08ddbd84ce14 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: BL3PR12MB6570 Content-Type: text/plain; charset="utf-8" Use attack vector controls to determine if ITS mitigation is required. Signed-off-by: David Kaplan --- arch/x86/kernel/cpu/bugs.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index c0e23e625b6f..7972c9b16e8a 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1514,13 +1514,17 @@ early_param("indirect_target_selection", its_parse_= cmdline); =20 static void __init its_select_mitigation(void) { - if (!boot_cpu_has_bug(X86_BUG_ITS) || cpu_mitigations_off()) { + if (!boot_cpu_has_bug(X86_BUG_ITS)) { its_mitigation =3D ITS_MITIGATION_OFF; return; } =20 - if (its_mitigation =3D=3D ITS_MITIGATION_AUTO) - its_mitigation =3D ITS_MITIGATION_ALIGNED_THUNKS; + if (its_mitigation =3D=3D ITS_MITIGATION_AUTO) { + if (should_mitigate_vuln(X86_BUG_ITS)) + its_mitigation =3D ITS_MITIGATION_ALIGNED_THUNKS; + else + its_mitigation =3D ITS_MITIGATION_OFF; + } =20 if (its_mitigation =3D=3D ITS_MITIGATION_OFF) return; @@ -1551,12 +1555,13 @@ static void __init its_select_mitigation(void) =20 static void __init its_update_mitigation(void) { - if (!boot_cpu_has_bug(X86_BUG_ITS) || cpu_mitigations_off()) + if (!boot_cpu_has_bug(X86_BUG_ITS)) return; =20 switch (spectre_v2_enabled) { case SPECTRE_V2_NONE: - pr_err("WARNING: Spectre-v2 mitigation is off, disabling ITS\n"); + if (its_mitigation !=3D ITS_MITIGATION_OFF) + pr_err("WARNING: Spectre-v2 mitigation is off, disabling ITS\n"); its_mitigation =3D ITS_MITIGATION_OFF; break; case SPECTRE_V2_RETPOLINE: --=20 2.34.1