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Peter Anvin" CC: Subject: [PATCH v6 08/21] x86/bugs: Add attack vector controls for RFDS Date: Mon, 7 Jul 2025 13:33:03 -0500 Message-ID: <20250707183316.1349127-9-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_|SJ0PR12MB6880:EE_ X-MS-Office365-Filtering-Correlation-Id: d7d20437-fdab-4ee1-fc02-08ddbd84ca4a X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|376014|7416014|1800799024|36860700013; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?f1ugFqJ0JrtsL3M0KVrs+k9RXV8VuCWv5tJ2nMDc1scNBKfmp6yLB0cVD1ND?= =?us-ascii?Q?aHI53eCvU+76Q7Tc0j7HvHavp6eW01KCZ6Fljm4u/Aap1GPFl26VvILBRduM?= =?us-ascii?Q?RonQo0utT2Lr05uetUrhiQBp2ZBnOqncDF6IzqrM/4GmYllMouZfUGUn8imo?= =?us-ascii?Q?jipNHNn39wParROWS+RyscNQzLqH+daSFkFZyi9g1eIKy8YiQXABFWMKrf5N?= =?us-ascii?Q?EMAkE6ISL80fDM2ekmEBK46YbKJEhKe3NTVIWKYq0QNoUsoJfGwNHaZMX9wf?= =?us-ascii?Q?gq1wO0SOagOeVCeb4LYvJMbPpDkUxHfFzkr8iILflObHxU1f/dZe+N6eKS+Q?= =?us-ascii?Q?iMVxZ6v0KIyl4XG8YXfllLXtocJEYBMy5oJUCXJHs+lkQPwwWU7EpU01T5Mv?= =?us-ascii?Q?8PJa6YEk8B2peDvdu4jw2oV5HFJJkIsJQuIpaDbB9Wjard1NcQpwaI0chvka?= =?us-ascii?Q?XG1xyvEDHqbriFF3g6F1Raed2Y71lJcf+Cg3b3W3W9XKMcpood/L31qe2sja?= =?us-ascii?Q?Eq156ZeboWbvPsuozPBlyPfExOFcL19P5iJh9nTR0PvaRNiUSYb6n3oaEpCR?= =?us-ascii?Q?XJi/GUtlArP7NtqWh2+XtpCtfDz/YjO5czA6tRrK8p/qyTi4BnNOx92riudn?= =?us-ascii?Q?faKUf1HfaD5kL513CKxCJu1sXJ2+J1p62mM1rMAVXqvFsrplMPozZqEPiomz?= =?us-ascii?Q?86e02Qq6ntxEA3GSCsdXtYJloYGg3/XhywX/vMA1V2tEjVLMzivXG8mdGcGw?= =?us-ascii?Q?0Cn8HfNaWV6NvD945ZJxjVSlM1ZjfTnUelomuI2WIH0cUyGKP3uUEbMQd45v?= =?us-ascii?Q?uMXWENrriVOWk5eVvHFL5TJM8+JGq+eBI+Kr60BQDCKo+zTp7NgB2Bfjdx+A?= =?us-ascii?Q?yoVHOGYvrVkAgTSyb2x2pBqLCsWq7NVgkKFucUQId3V4f+u0eD3V2jYrLxF1?= =?us-ascii?Q?Q2JDBiCbxwbL57VSPQMK8FCOFSkZHBFTjQEyRI4TR8Z/fiyRGZ0XlnNqHbSV?= =?us-ascii?Q?c55MbkRG4n94sXUtKIkGE3wKtPMH7ZCS0RNrFaEuK7DQSi/oGU7B865twZyy?= =?us-ascii?Q?Z1t71MIX6/ZAAMVuZaQW/dpOQnT0hMtrP1mhvjRfAeYeRKYJAxwXtpzDgf7b?= =?us-ascii?Q?mgaaMYZZ0+sbEVL1GhSt+JSR8v2kuWcHSN04QMm5Ahdj7de7Rneh1HQl7uj/?= =?us-ascii?Q?Zz/jgD7WrZ6lgaAutLTZmyff3aSS+ffVELdPaEJZUQxZbHi61GtPkLIjMi4V?= =?us-ascii?Q?8ZwUsUD0Opi2uJIxPpK5DzojGfAz1wq7ChBJfTtRgbjZ/JsmIpwHX30sAJiq?= =?us-ascii?Q?wem12pMzOBhv4WAzf40IGSDGWlhEDrbJM2MegouSdB0pqiEUTK3HxHX45kF0?= =?us-ascii?Q?oqR30ONuoUjdfJ+wm0txJT+wCerqs2X1RU6AQJGtzyaJhdq4TwleNFcQsuGF?= =?us-ascii?Q?LbtzGkOkBUAew0mtAxDuxN74qkQ4AJ/dpppx3WbA760eP+5eckccTRN5EvEU?= =?us-ascii?Q?5cgCM2ycjys0KcCqRQBwT5J31SBo2jfExV0U?= 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)(376014)(7416014)(1800799024)(36860700013);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Jul 2025 18:33:38.2378 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: d7d20437-fdab-4ee1-fc02-08ddbd84ca4a 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: SJ0PR12MB6880 Content-Type: text/plain; charset="utf-8" Use attack vector controls to determine if RFDS mitigation is required. Signed-off-by: David Kaplan --- arch/x86/kernel/cpu/bugs.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 9f81a236735f..cf7d010931b9 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -744,13 +744,17 @@ static inline bool __init verw_clears_cpu_reg_file(vo= id) =20 static void __init rfds_select_mitigation(void) { - if (!boot_cpu_has_bug(X86_BUG_RFDS) || cpu_mitigations_off()) { + if (!boot_cpu_has_bug(X86_BUG_RFDS)) { rfds_mitigation =3D RFDS_MITIGATION_OFF; return; } =20 - if (rfds_mitigation =3D=3D RFDS_MITIGATION_AUTO) - rfds_mitigation =3D RFDS_MITIGATION_VERW; + if (rfds_mitigation =3D=3D RFDS_MITIGATION_AUTO) { + if (should_mitigate_vuln(X86_BUG_RFDS)) + rfds_mitigation =3D RFDS_MITIGATION_VERW; + else + rfds_mitigation =3D RFDS_MITIGATION_OFF; + } =20 if (rfds_mitigation =3D=3D RFDS_MITIGATION_OFF) return; @@ -761,7 +765,7 @@ static void __init rfds_select_mitigation(void) =20 static void __init rfds_update_mitigation(void) { - if (!boot_cpu_has_bug(X86_BUG_RFDS) || cpu_mitigations_off()) + if (!boot_cpu_has_bug(X86_BUG_RFDS)) return; =20 if (verw_clear_cpu_buf_mitigation_selected) --=20 2.34.1