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Peter Anvin" CC: Subject: [PATCH v5 14/16] x86/bugs: Restructure SSB mitigation Date: Fri, 18 Apr 2025 11:17:19 -0500 Message-ID: <20250418161721.1855190-15-david.kaplan@amd.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250418161721.1855190-1-david.kaplan@amd.com> References: <20250418161721.1855190-1-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: SATLEXMB03.amd.com (10.181.40.144) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS2PEPF0000343E:EE_|MN0PR12MB5929:EE_ X-MS-Office365-Filtering-Correlation-Id: 7051c4da-cf86-4f7b-50df-08dd7e948c15 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|7416014|376014|1800799024|36860700013; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?KJu3uqUUuI/9QLnkbyvVHPLj0SzMFn9gjQnzLJpmsmeO3BxIcJNdXt0dOZAu?= =?us-ascii?Q?lo7edFP6Kbn5FQ8I2iE/mmw7s3KUecaEwSmeznG3GvXqxJ3WgfkJUiQHDh04?= =?us-ascii?Q?goQs6wPHou7kPZUZyH6WtB0H0FVGJpuLxbMtbNFr6tYhaOmf4s/CeLz5bH3y?= =?us-ascii?Q?T/VCqdg4PNrIEyFyPvX2CgLZ576I9zz1HDbaWTaWLHrVL14dm3cYA83nmkoN?= =?us-ascii?Q?J95YD2YFvNStGiyGBZCY9u5vnCsSeTtofzxyr2ytbs+JfARe0RVNwLs4K0wf?= =?us-ascii?Q?5hbtz4iixosHAe74WKjRXlvW/+YoTynByAK2ou3Yo2bvULByGk/tSMkujAYC?= =?us-ascii?Q?UQohk3tFkWrulQP2NC/cia9Cm9eH5tlDHkAL187XesVVjpvQiwVDR4hMMGaW?= =?us-ascii?Q?px6C1urGADjW7sEK62QzU0QZxUExqSTEqxrl+YiT3u5sOwqQOzSMORdBcfm8?= =?us-ascii?Q?R8SautzaFCLJ3o6AsIp44NIWKs7/0z4VtZQdBDpx8F294uTMPh6FhUpPb6zW?= =?us-ascii?Q?BMsc9bny8mBnZ8PHcZRAUjAgKd+wAMHqavC0YG3wdKPNJJ1/8Be16otQanm5?= =?us-ascii?Q?OaCDoKcdeXzPwIxYaLq47/5WVW42SxGo6DzHhEV3+yFpGoI0FhC3zfF5rxM5?= =?us-ascii?Q?y/nF1ezTWUW91OMPgzII+68vnf9dYTHMvyrDCH2+P9+RgVyhoyIviTxVVI9A?= =?us-ascii?Q?bsHBdCZ9EZMBOqzw71UjGrLFmKTBOoQQVGIXw3i+txodQ0QB4Idz+bbkExEa?= =?us-ascii?Q?5MH6eHB7cmL8sP30yzzzhVHLD6yQu6QwvUg59EcRW9d//suCsqdhgXGs3xSH?= =?us-ascii?Q?4aBHuL2QCX5PrVaNhPFNc/MKDAdK0hK9hOPbsI7DhDzDkhhW5rCeddQI/8xf?= =?us-ascii?Q?uOUglFnU+hZtdlLvEAcnlCB8df5cyusJnGyHU/4aUQyPu1rvhns6ifDh49Rs?= =?us-ascii?Q?wSLmluAD6tMbjLIRHDC5Bu+DAgajGFWaDJg/QOujZ1kd2LqsDjCZW/aP950H?= =?us-ascii?Q?vuViuIWm0wXJ7uGWe+6LDUCwe55tkfUkMr170pvR4T6ONE8587tj5MfGsQsr?= =?us-ascii?Q?jI3CqA5qcoBxHid9fdj00+7Jn/T44/TYQXdYa9aBHw0QU8+N1Q57TVsS0gNQ?= =?us-ascii?Q?PDsLykmrujP2xJv9aSHLnJovafvHGbWRyJl59KW43XISgpL/KIMlcLSurWD4?= =?us-ascii?Q?QcGovygSIJeiKDcdADgGOtdGZfHSVxFskU1Eh0c+4etyIhpmCpJ2jGGhKS3J?= =?us-ascii?Q?22LxHbFnn9pGUfJpH8gt9DDQRrV2b1GXa1Gz77zcWZroGvMVNDf3S4AuhozF?= =?us-ascii?Q?jv37/i828N/DQV7wd9BGTHKhUdQKTbXPDu80J+p9JniHzWlZCF+mqW8kgnxo?= =?us-ascii?Q?Tdsf0C3ttRPReQt1j6//F79AvysYY3fSmJ+M8HQZSq4om/tvLiVGAYCd6aiL?= =?us-ascii?Q?2+fAPGJicjWfqO5rB1+9HHPKPMtgQPDp/smMLuLrV5oxvIrV2CXtOtUs9fEy?= =?us-ascii?Q?MDxUQ1bZnHy48/Hh93Wuyup20QC2b//qF/Ks?= 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)(1800799024)(36860700013);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Apr 2025 16:17:42.6111 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 7051c4da-cf86-4f7b-50df-08dd7e948c15 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: DS2PEPF0000343E.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN0PR12MB5929 Content-Type: text/plain; charset="utf-8" Restructure SSB to use select/apply functions to create consistent vulnerability handling. Remove __ssb_select_mitigation() and split the functionality between the select/apply functions. Signed-off-by: David Kaplan --- arch/x86/kernel/cpu/bugs.c | 36 +++++++++++++++++------------------- 1 file changed, 17 insertions(+), 19 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 8fe00fe987d5..e526d06171cd 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -65,6 +65,7 @@ static void __init spectre_v2_user_select_mitigation(void= ); static void __init spectre_v2_user_update_mitigation(void); static void __init spectre_v2_user_apply_mitigation(void); static void __init ssb_select_mitigation(void); +static void __init ssb_apply_mitigation(void); static void __init l1tf_select_mitigation(void); static void __init mds_select_mitigation(void); static void __init mds_update_mitigation(void); @@ -241,6 +242,7 @@ void __init cpu_select_mitigations(void) spectre_v2_apply_mitigation(); retbleed_apply_mitigation(); spectre_v2_user_apply_mitigation(); + ssb_apply_mitigation(); mds_apply_mitigation(); taa_apply_mitigation(); mmio_apply_mitigation(); @@ -2224,19 +2226,18 @@ static enum ssb_mitigation_cmd __init ssb_parse_cmd= line(void) return cmd; } =20 -static enum ssb_mitigation __init __ssb_select_mitigation(void) +static void ssb_select_mitigation(void) { - enum ssb_mitigation mode =3D SPEC_STORE_BYPASS_NONE; enum ssb_mitigation_cmd cmd; =20 if (!boot_cpu_has(X86_FEATURE_SSBD)) - return mode; + goto out; =20 cmd =3D ssb_parse_cmdline(); if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS) && (cmd =3D=3D SPEC_STORE_BYPASS_CMD_NONE || cmd =3D=3D SPEC_STORE_BYPASS_CMD_AUTO)) - return mode; + return; =20 switch (cmd) { case SPEC_STORE_BYPASS_CMD_SECCOMP: @@ -2245,28 +2246,35 @@ static enum ssb_mitigation __init __ssb_select_miti= gation(void) * enabled. */ if (IS_ENABLED(CONFIG_SECCOMP)) - mode =3D SPEC_STORE_BYPASS_SECCOMP; + ssb_mode =3D SPEC_STORE_BYPASS_SECCOMP; else - mode =3D SPEC_STORE_BYPASS_PRCTL; + ssb_mode =3D SPEC_STORE_BYPASS_PRCTL; break; case SPEC_STORE_BYPASS_CMD_ON: - mode =3D SPEC_STORE_BYPASS_DISABLE; + ssb_mode =3D SPEC_STORE_BYPASS_DISABLE; break; case SPEC_STORE_BYPASS_CMD_AUTO: case SPEC_STORE_BYPASS_CMD_PRCTL: - mode =3D SPEC_STORE_BYPASS_PRCTL; + ssb_mode =3D SPEC_STORE_BYPASS_PRCTL; break; case SPEC_STORE_BYPASS_CMD_NONE: break; } =20 +out: + if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS)) + pr_info("%s\n", ssb_strings[ssb_mode]); +} + +static void __init ssb_apply_mitigation(void) +{ /* * We have three CPU feature flags that are in play here: * - X86_BUG_SPEC_STORE_BYPASS - CPU is susceptible. * - X86_FEATURE_SSBD - CPU is able to turn off speculative store bypass * - X86_FEATURE_SPEC_STORE_BYPASS_DISABLE - engage the mitigation */ - if (mode =3D=3D SPEC_STORE_BYPASS_DISABLE) { + if (ssb_mode =3D=3D SPEC_STORE_BYPASS_DISABLE) { setup_force_cpu_cap(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE); /* * Intel uses the SPEC CTRL MSR Bit(2) for this, while AMD may @@ -2280,16 +2288,6 @@ static enum ssb_mitigation __init __ssb_select_mitig= ation(void) update_spec_ctrl(x86_spec_ctrl_base); } } - - return mode; -} - -static void ssb_select_mitigation(void) -{ - ssb_mode =3D __ssb_select_mitigation(); - - if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS)) - pr_info("%s\n", ssb_strings[ssb_mode]); } =20 #undef pr_fmt --=20 2.34.1