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Peter Anvin" CC: Subject: [PATCH v3 1/7] x86/bugs: Use early_param for spectre_v2_user Date: Mon, 15 Sep 2025 08:47:00 -0500 Message-ID: <20250915134706.3201818-2-david.kaplan@amd.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250915134706.3201818-1-david.kaplan@amd.com> References: <20250915134706.3201818-1-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: satlexmb08.amd.com (10.181.42.217) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ5PEPF000001D4:EE_|DM6PR12MB4371:EE_ X-MS-Office365-Filtering-Correlation-Id: 26c7723c-0f50-45dd-3056-08ddf45e661d X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700013|376014|7416014|1800799024|82310400026; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?NHT+JLsTQB3+a08/58m/MHc7I+qZ/z4aL7kM/6iIcnFyic+YPxZbXTQc1+Sc?= =?us-ascii?Q?gJKUTFnIIxO3k8KZmBOyHtvCpBsAs5isje2EUNE1prlUHGGZwH2/7dtFGKV3?= =?us-ascii?Q?ZSWtG3yr5gnVrEkpKOBKR/SiCBP6zhXJmiftvcHO4wdJLvxJr20UMJudFEYw?= =?us-ascii?Q?sZNUaqOHkzai38Fin8zvjXtIbc1gfGU0Rx2hMhNNcHJwqoRsq27it3AoYIRF?= =?us-ascii?Q?9KMeSjh/5R26M561GDMPfW8vWWIOAf4efk7foLH0CSgUTtjsCwGPUAHPv6BD?= =?us-ascii?Q?HDqAvaX4wMDYUUEu9SDkSIvu2+zuCjngUootkr5WuI07S4EneNs0cgnT/8Tx?= =?us-ascii?Q?8jzssZ6363hejzkNn+fXfV5VA0vhwzHxe3azjbBPw+dg1SMHexgik9oYFOkz?= =?us-ascii?Q?javGAsOlnGz5CKTabGOsnMb7iZ73du7b4TEzmvHxfyaHRgUXv/dYZThY9i3c?= =?us-ascii?Q?SnVar8IhHQcHNj7M8sgCVl2L5JHmbTAK8iP5HqJs+fspm6sTXGXR+xR42ctP?= =?us-ascii?Q?T472+WYFzJiJA4cokHIlX8Yd6uG/etnea3PmCN+VGDZ4ezeWy4TIUxl7FZGq?= =?us-ascii?Q?Qdv0T2gwdyOIlAAbt583qzpfTETmdZgdB5bnHEnzYpRYY7dh2ijHurd0rCV9?= =?us-ascii?Q?7hoOa/cVS6T9mYNl3O9REZh8KO/GDbZgDUVD1+mwH2XL5jTSQdj5HiyhSrrS?= =?us-ascii?Q?Mr0Gdo5ys4OyB1DBZ9vc8/N7RFjsHQWczCLGoXWqyPd4MagvM/2YPlXu9ffk?= =?us-ascii?Q?JCOALTk4r3zLGPDtzFd/iUsc3VpMhX+4xueyL0wMsOzbOel7DWspf62p5oCA?= =?us-ascii?Q?ikkv16BKTT4IgpSjGwiY+BE/OxL/pK7fLejAZY+nJNe6J6vtPlKiUNsd1E2r?= =?us-ascii?Q?PhHfNz5Df+CJFWVtBvqUvh6KKdEG9+HXpFhCX8M6+lGDqRCt2sUKr8IfXPIO?= =?us-ascii?Q?nXsvIs4H4g9gQvffQZSQVEQu0texV2AXdu5dotmhXxOOODbaCHZub3RrC18R?= =?us-ascii?Q?TymH5UaBwkEycI8Z74s3MGSwsRz6eC4mNYqEC5pMTpi6BsGZdwVZEieJpOND?= =?us-ascii?Q?8MOUP3OcTdn/n6A7hav85cdfSwa6HtT/IBnNhpO/n4OxW5KiUKUE0wKnQ7uE?= =?us-ascii?Q?2D3kZtxqD8X51z3SMaaxblbgD93hLpUq473dV5YzkKKyBBAjuwkuhJrA+U05?= =?us-ascii?Q?icTAKSEyRlpuxUsDF2Hvc3i2eVAkFKXYUAOeCqWKmBv9dBW2/YEpTk3ItXuw?= =?us-ascii?Q?lYgx0pdbI/PPaudfjpTs+ljuigx0ba5cKY8iZAmOdbka/LOhTuAWBX17zEzo?= =?us-ascii?Q?OAFlNvJwljBKo6cxn/Ngeph7pEzqQinvWw6jUEjjaX7ZkB/n9pbWBj2RcmmX?= =?us-ascii?Q?OwJ7XWG121gnIlVQkfmkB0mFuLJMlgIKBgEj1I6TYPW+h0HAlecHk7pcFxJa?= =?us-ascii?Q?Yj693p3ELezJ1arWH/DEywHK3Me7hhcPZNriyOf2MB3aMSTAYAbTycED9mtB?= =?us-ascii?Q?qm2Dw6McMRmGeNCCQgdLLL4av7efK4xw4A4Q?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(36860700013)(376014)(7416014)(1800799024)(82310400026);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Sep 2025 13:47:23.2433 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 26c7723c-0f50-45dd-3056-08ddf45e661d 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=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SJ5PEPF000001D4.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR12MB4371 Content-Type: text/plain; charset="utf-8" Most of the mitigations in bugs.c use early_param to parse their command line options. Modify spectre_v2_user to use early_param for consistency. Remove spec_v2_user_print_cond() because informing a user about their cmdline choice isn't very interesting and the chosen mitigation is already printed in spectre_v2_user_update_mitigation(). Signed-off-by: David Kaplan Reviewed-by: Pawan Gupta --- arch/x86/kernel/cpu/bugs.c | 68 +++++++++++++++----------------------- 1 file changed, 26 insertions(+), 42 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index e817bbae0159..a5072ec6e5c5 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1847,7 +1847,7 @@ enum spectre_v2_mitigation_cmd { =20 static enum spectre_v2_mitigation_cmd spectre_v2_cmd __ro_after_init =3D S= PECTRE_V2_CMD_AUTO; =20 -enum spectre_v2_user_cmd { +enum spectre_v2_user_mitigation_cmd { SPECTRE_V2_USER_CMD_NONE, SPECTRE_V2_USER_CMD_AUTO, SPECTRE_V2_USER_CMD_FORCE, @@ -1857,6 +1857,9 @@ enum spectre_v2_user_cmd { SPECTRE_V2_USER_CMD_SECCOMP_IBPB, }; =20 +static enum spectre_v2_user_mitigation_cmd spectre_v2_user_cmd __ro_after_= init =3D + IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2) ? SPECTRE_V2_USER_CMD_AUTO : SPE= CTRE_V2_USER_CMD_NONE; + static const char * const spectre_v2_user_strings[] =3D { [SPECTRE_V2_USER_NONE] =3D "User space: Vulnerable", [SPECTRE_V2_USER_STRICT] =3D "User space: Mitigation: STIBP protection", @@ -1865,50 +1868,31 @@ static const char * const spectre_v2_user_strings[]= =3D { [SPECTRE_V2_USER_SECCOMP] =3D "User space: Mitigation: STIBP via seccomp= and prctl", }; =20 -static const struct { - const char *option; - enum spectre_v2_user_cmd cmd; - bool secure; -} v2_user_options[] __initconst =3D { - { "auto", SPECTRE_V2_USER_CMD_AUTO, false }, - { "off", SPECTRE_V2_USER_CMD_NONE, false }, - { "on", SPECTRE_V2_USER_CMD_FORCE, true }, - { "prctl", SPECTRE_V2_USER_CMD_PRCTL, false }, - { "prctl,ibpb", SPECTRE_V2_USER_CMD_PRCTL_IBPB, false }, - { "seccomp", SPECTRE_V2_USER_CMD_SECCOMP, false }, - { "seccomp,ibpb", SPECTRE_V2_USER_CMD_SECCOMP_IBPB, false }, -}; - -static void __init spec_v2_user_print_cond(const char *reason, bool secure) -{ - if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2) !=3D secure) - pr_info("spectre_v2_user=3D%s forced on command line.\n", reason); -} - -static enum spectre_v2_user_cmd __init spectre_v2_parse_user_cmdline(void) +static int __init spectre_v2_user_parse_cmdline(char *str) { - char arg[20]; - int ret, i; - - if (!IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2)) - return SPECTRE_V2_USER_CMD_NONE; - - ret =3D cmdline_find_option(boot_command_line, "spectre_v2_user", - arg, sizeof(arg)); - if (ret < 0) - return SPECTRE_V2_USER_CMD_AUTO; + if (!str) + return -EINVAL; =20 - for (i =3D 0; i < ARRAY_SIZE(v2_user_options); i++) { - if (match_option(arg, ret, v2_user_options[i].option)) { - spec_v2_user_print_cond(v2_user_options[i].option, - v2_user_options[i].secure); - return v2_user_options[i].cmd; - } - } + if (!strcmp(str, "auto")) + spectre_v2_user_cmd =3D SPECTRE_V2_USER_CMD_AUTO; + else if (!strcmp(str, "off")) + spectre_v2_user_cmd =3D SPECTRE_V2_USER_CMD_NONE; + else if (!strcmp(str, "on")) + spectre_v2_user_cmd =3D SPECTRE_V2_USER_CMD_FORCE; + else if (!strcmp(str, "prctl")) + spectre_v2_user_cmd =3D SPECTRE_V2_USER_CMD_PRCTL; + else if (!strcmp(str, "prctl,ibpb")) + spectre_v2_user_cmd =3D SPECTRE_V2_USER_CMD_PRCTL_IBPB; + else if (!strcmp(str, "seccomp")) + spectre_v2_user_cmd =3D SPECTRE_V2_USER_CMD_SECCOMP; + else if (!strcmp(str, "seccomp,ibpb")) + spectre_v2_user_cmd =3D SPECTRE_V2_USER_CMD_SECCOMP_IBPB; + else + pr_err("Ignoring unknown spectre_v2_user option (%s).", str); =20 - pr_err("Unknown user space protection option (%s). Switching to default\n= ", arg); - return SPECTRE_V2_USER_CMD_AUTO; + return 0; } +early_param("spectre_v2_user", spectre_v2_user_parse_cmdline); =20 static inline bool spectre_v2_in_ibrs_mode(enum spectre_v2_mitigation mode) { @@ -1920,7 +1904,7 @@ static void __init spectre_v2_user_select_mitigation(= void) if (!boot_cpu_has(X86_FEATURE_IBPB) && !boot_cpu_has(X86_FEATURE_STIBP)) return; =20 - switch (spectre_v2_parse_user_cmdline()) { + switch (spectre_v2_user_cmd) { case SPECTRE_V2_USER_CMD_NONE: return; case SPECTRE_V2_USER_CMD_FORCE: --=20 2.34.1