x86/bugs: Use early_param() for spectre_v2_user

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 <david.kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Link: https://lore.kernel.org/r/20250819192200.2003074-2-david.kaplan@amd.com

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index e817bbae01591b73d7868ccf56cd459c436654f4..a5072ec6e5c5e5e6f81619ab63b0c32dec240f1c 100644 (file)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1847,7 +1847,7 @@ enum spectre_v2_mitigation_cmd {
 
 static enum spectre_v2_mitigation_cmd spectre_v2_cmd __ro_after_init = SPECTRE_V2_CMD_AUTO;
 
-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,
 };
 
+static enum spectre_v2_user_mitigation_cmd spectre_v2_user_cmd __ro_after_init =
+       IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2) ? SPECTRE_V2_USER_CMD_AUTO : SPECTRE_V2_USER_CMD_NONE;
+
 static const char * const spectre_v2_user_strings[] = {
        [SPECTRE_V2_USER_NONE]                  = "User space: Vulnerable",
        [SPECTRE_V2_USER_STRICT]                = "User space: Mitigation: STIBP protection",
@@ -1865,50 +1868,31 @@ static const char * const spectre_v2_user_strings[] = {
        [SPECTRE_V2_USER_SECCOMP]               = "User space: Mitigation: STIBP via seccomp and prctl",
 };
 
-static const struct {
-       const char                      *option;
-       enum spectre_v2_user_cmd        cmd;
-       bool                            secure;
-} v2_user_options[] __initconst = {
-       { "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) != secure)
-               pr_info("spectre_v2_user=%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 = 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;
 
-       for (i = 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 = SPECTRE_V2_USER_CMD_AUTO;
+       else if (!strcmp(str, "off"))
+               spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_NONE;
+       else if (!strcmp(str, "on"))
+               spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_FORCE;
+       else if (!strcmp(str, "prctl"))
+               spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_PRCTL;
+       else if (!strcmp(str, "prctl,ibpb"))
+               spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_PRCTL_IBPB;
+       else if (!strcmp(str, "seccomp"))
+               spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_SECCOMP;
+       else if (!strcmp(str, "seccomp,ibpb"))
+               spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_SECCOMP_IBPB;
+       else
+               pr_err("Ignoring unknown spectre_v2_user option (%s).", str);
 
-       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);
 
 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;
 
-       switch (spectre_v2_parse_user_cmdline()) {
+       switch (spectre_v2_user_cmd) {
        case SPECTRE_V2_USER_CMD_NONE:
                return;
        case SPECTRE_V2_USER_CMD_FORCE: