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Peter Anvin" CC: , Brendan Jackman , Derek Manwaring Subject: [PATCH v4 14/36] x86/bugs: Restructure ssb mitigation Date: Mon, 10 Mar 2025 11:40:01 -0500 Message-ID: <20250310164023.779191-15-david.kaplan@amd.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250310164023.779191-1-david.kaplan@amd.com> References: <20250310164023.779191-1-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: BL6PEPF00022572:EE_|CH2PR12MB4070:EE_ X-MS-Office365-Filtering-Correlation-Id: 135816dd-3d15-4bd0-4de3-08dd5ff2506d X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|376014|7416014|36860700013|1800799024; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?Or3/jHcm+qwaNys0fM42TkzPGbZ+n//CuSJcn/5xeRvw5GBkeH2Tf4yd2RE7?= =?us-ascii?Q?3K26L2C7+QNDWkILrnNP48YmipjGds8b1BqXWyc/EPH+Tebjg4+kaSg6VCe6?= =?us-ascii?Q?Pbk4o3eXxLOT89SBmFLJcowH0okEythG0Q3yMD+HqzKFp7iTVKgiVx4TMLi8?= =?us-ascii?Q?W2pmbtsizdZIF0gxm74+yCIr9uQ/3j94OrDUefEd4KfigQPFamAcuYc8s+Q4?= =?us-ascii?Q?KAk0KZLEEoqko3yP47Zd96ihIsXiMGzD9lRnMxHRL9tA/22oRF0JuxFxlPD/?= =?us-ascii?Q?YbcnxdWmujXpPMGAIgsFNkiNKAdUUDHuHJqvgDCddCXcsmsK0hvIFNl2BcAc?= =?us-ascii?Q?Uzt98Uhv4b7jX12j27I7yhX0cKhUnaHpRggJeU6zW4g2LHc2uxzSNvY9luib?= =?us-ascii?Q?ZbQtAw3VC7eOzXmQwnt3dzVS7YLrsnYtUqZH+Az3EIx1jBhAAdV/mm7uabZ2?= =?us-ascii?Q?mmPoazT7ioMontfxEQZdUy/1aL7Xl39K/uOH/SuccupJtfi+HwDiFz3/Bi0W?= =?us-ascii?Q?RYHN8/wparHopErXKkUDw0eiRuokJTknIwaimBFRJ5gRO2dfVzcQKjPJdADC?= =?us-ascii?Q?PRLANtNtIeZNzaTVDqvGcg04v7dXA3UEQAOAW9d7EVxpuZURmt5DZC4ZgAGE?= =?us-ascii?Q?4Ex/V34TmpWScNERWWT8ndzpD67qHvVEZlFzzvc+O4VggiubzcmhNVA1SSYo?= =?us-ascii?Q?/qf/rN+/bXMm1JMx+LjYPHPCBnwtkLNYJomVFoYhq+gwh0mkEN6ExJcN4eIs?= =?us-ascii?Q?3CgjyXQ0yxsv83TwQeaQSuIKEl9EYpz9QKGjCJBPQRd7qYYxvCnAeIdtKOiO?= =?us-ascii?Q?VdAK0dNAI/BVntpbZlFL1V8M1B4IflgreTItuIRoRd2fKTTvQXeCmce1uYJp?= =?us-ascii?Q?uK+T5l+S16v8qpEx1v6eUY50sUuqzjucKpRkHM90/io1z9FD51RGEGm6X6Ji?= =?us-ascii?Q?QMCEIOd3BTjhIEcwta/IsPfseQkC4inC9yYb7oKRGbqmNqwG2DmqUz+mGtej?= =?us-ascii?Q?AKmqB7Xbg1KegX0NGiv0RaNrH5p21bApRoWfE034Ln+WCusfNtJx3xz2L9Sf?= =?us-ascii?Q?xbUunZiZhHS1hdCvrzGTNamEHg2VKqXZE5yUdXLBI4GtizhfDnhA2jilNGxh?= =?us-ascii?Q?wINc1r3GqbeK+/qgNLVin7TAmNHsV/1icamcJgiB9szC66LLWWIptO2VvaMC?= =?us-ascii?Q?knvK80bZ9FZOPgOXbm/mMgUJ0eDwgvOUt2OwAGuzW/pqveXKFllPiSI4i6/P?= =?us-ascii?Q?L4t9fO3FxOApkbRUHrCqTiR2TaKJJyglrALPXqDFnRiWTF8tTdGSQyxhSzxB?= =?us-ascii?Q?2kGN95S+cgeQgz16i2f6vnB8zJJVedhZcuO0SmtejKOenI18+7rlQsGyPJGw?= =?us-ascii?Q?mlNFEt2VAEWWckMRdXz7pEelxgr99teCelVAfBpLO8wjD+kl4yHsKq3f2ZaD?= =?us-ascii?Q?k9WUzljg2SrTbcN3ibH/5DIfns5ekks4Yh2cZddPPjabF9Khpv6MBsjfBnpt?= =?us-ascii?Q?g6tnARKQbieRGlM=3D?= 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)(36860700013)(1800799024);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Mar 2025 16:40:49.2074 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 135816dd-3d15-4bd0-4de3-08dd5ff2506d 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: BL6PEPF00022572.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH2PR12MB4070 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 b4a72ddf159c..1d77747e0f74 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); @@ -232,6 +233,7 @@ 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(); @@ -2235,19 +2237,18 @@ 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: @@ -2256,28 +2257,35 @@ 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 @@ -2291,16 +2299,6 @@ 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