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x86/bugs: Use early_param() for spectre_v2

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Most of the mitigations in bugs.c use early_param() for command line parsing.
Rework the spectre_v2 and nospectre_v2 command line options to be
consistent with the others.

Remove spec_v2_print_cond() as informing the user of the their cmdline
choice isn't interesting.

  [ bp: Zap spectre_v2_check_cmd(). ]

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/20250819192200.2003074-3-david.kaplan@amd.com
This commit is contained in:
David Kaplan 2025-09-15 08:47:01 -05:00 committed by Borislav Petkov (AMD)
parent 8edb9e7711
commit 9a9f8147ae
1 changed files with 82 additions and 99 deletions
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181
arch/x86/kernel/cpu/bugs.c
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@ -1845,7 +1845,8 @@ enum spectre_v2_mitigation_cmd {
SPECTRE_V2_CMD_IBRS,
};
static enum spectre_v2_mitigation_cmd spectre_v2_cmd __ro_after_init = SPECTRE_V2_CMD_AUTO;
static enum spectre_v2_mitigation_cmd spectre_v2_cmd __ro_after_init =
IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2) ? SPECTRE_V2_CMD_AUTO : SPECTRE_V2_CMD_NONE;
enum spectre_v2_user_mitigation_cmd {
SPECTRE_V2_USER_CMD_NONE,
@ -2039,112 +2040,51 @@ static const char * const spectre_v2_strings[] = {
[SPECTRE_V2_IBRS] = "Mitigation: IBRS",
};
static const struct {
const char *option;
enum spectre_v2_mitigation_cmd cmd;
bool secure;
} mitigation_options[] __initconst = {
{ "off", SPECTRE_V2_CMD_NONE, false },
{ "on", SPECTRE_V2_CMD_FORCE, true },
{ "retpoline", SPECTRE_V2_CMD_RETPOLINE, false },
{ "retpoline,amd", SPECTRE_V2_CMD_RETPOLINE_LFENCE, false },
{ "retpoline,lfence", SPECTRE_V2_CMD_RETPOLINE_LFENCE, false },
{ "retpoline,generic", SPECTRE_V2_CMD_RETPOLINE_GENERIC, false },
{ "eibrs", SPECTRE_V2_CMD_EIBRS, false },
{ "eibrs,lfence", SPECTRE_V2_CMD_EIBRS_LFENCE, false },
{ "eibrs,retpoline", SPECTRE_V2_CMD_EIBRS_RETPOLINE, false },
{ "auto", SPECTRE_V2_CMD_AUTO, false },
{ "ibrs", SPECTRE_V2_CMD_IBRS, false },
};
static bool nospectre_v2 __ro_after_init;
static void __init spec_v2_print_cond(const char *reason, bool secure)
static int __init nospectre_v2_parse_cmdline(char *str)
{
if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2) != secure)
pr_info("%s selected on command line.\n", reason);
nospectre_v2 = true;
spectre_v2_cmd = SPECTRE_V2_CMD_NONE;
return 0;
}
early_param("nospectre_v2", nospectre_v2_parse_cmdline);
static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
static int __init spectre_v2_parse_cmdline(char *str)
{
enum spectre_v2_mitigation_cmd cmd;
char arg[20];
int ret, i;
if (!str)
return -EINVAL;
cmd = IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2) ? SPECTRE_V2_CMD_AUTO : SPECTRE_V2_CMD_NONE;
if (cmdline_find_option_bool(boot_command_line, "nospectre_v2"))
return SPECTRE_V2_CMD_NONE;
if (nospectre_v2)
return 0;
ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, sizeof(arg));
if (ret < 0)
return cmd;
if (!strcmp(str, "off"))
spectre_v2_cmd = SPECTRE_V2_CMD_NONE;
else if (!strcmp(str, "on"))
spectre_v2_cmd = SPECTRE_V2_CMD_FORCE;
else if (!strcmp(str, "retpoline"))
spectre_v2_cmd = SPECTRE_V2_CMD_RETPOLINE;
else if (!strcmp(str, "retpoline,amd") ||
!strcmp(str, "retpoline,lfence"))
spectre_v2_cmd = SPECTRE_V2_CMD_RETPOLINE_LFENCE;
else if (!strcmp(str, "retpoline,generic"))
spectre_v2_cmd = SPECTRE_V2_CMD_RETPOLINE_GENERIC;
else if (!strcmp(str, "eibrs"))
spectre_v2_cmd = SPECTRE_V2_CMD_EIBRS;
else if (!strcmp(str, "eibrs,lfence"))
spectre_v2_cmd = SPECTRE_V2_CMD_EIBRS_LFENCE;
else if (!strcmp(str, "eibrs,retpoline"))
spectre_v2_cmd = SPECTRE_V2_CMD_EIBRS_RETPOLINE;
else if (!strcmp(str, "auto"))
spectre_v2_cmd = SPECTRE_V2_CMD_AUTO;
else if (!strcmp(str, "ibrs"))
spectre_v2_cmd = SPECTRE_V2_CMD_IBRS;
else
pr_err("Ignoring unknown spectre_v2 option (%s).", str);
for (i = 0; i < ARRAY_SIZE(mitigation_options); i++) {
if (!match_option(arg, ret, mitigation_options[i].option))
continue;
cmd = mitigation_options[i].cmd;
break;
}
if (i >= ARRAY_SIZE(mitigation_options)) {
pr_err("unknown option (%s). Switching to default mode\n", arg);
return cmd;
}
if ((cmd == SPECTRE_V2_CMD_RETPOLINE ||
cmd == SPECTRE_V2_CMD_RETPOLINE_LFENCE ||
cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC ||
cmd == SPECTRE_V2_CMD_EIBRS_LFENCE ||
cmd == SPECTRE_V2_CMD_EIBRS_RETPOLINE) &&
!IS_ENABLED(CONFIG_MITIGATION_RETPOLINE)) {
pr_err("%s selected but not compiled in. Switching to AUTO select\n",
mitigation_options[i].option);
return SPECTRE_V2_CMD_AUTO;
}
if ((cmd == SPECTRE_V2_CMD_EIBRS ||
cmd == SPECTRE_V2_CMD_EIBRS_LFENCE ||
cmd == SPECTRE_V2_CMD_EIBRS_RETPOLINE) &&
!boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) {
pr_err("%s selected but CPU doesn't have Enhanced or Automatic IBRS. Switching to AUTO select\n",
mitigation_options[i].option);
return SPECTRE_V2_CMD_AUTO;
}
if ((cmd == SPECTRE_V2_CMD_RETPOLINE_LFENCE ||
cmd == SPECTRE_V2_CMD_EIBRS_LFENCE) &&
!boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) {
pr_err("%s selected, but CPU doesn't have a serializing LFENCE. Switching to AUTO select\n",
mitigation_options[i].option);
return SPECTRE_V2_CMD_AUTO;
}
if (cmd == SPECTRE_V2_CMD_IBRS && !IS_ENABLED(CONFIG_MITIGATION_IBRS_ENTRY)) {
pr_err("%s selected but not compiled in. Switching to AUTO select\n",
mitigation_options[i].option);
return SPECTRE_V2_CMD_AUTO;
}
if (cmd == SPECTRE_V2_CMD_IBRS && boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) {
pr_err("%s selected but not Intel CPU. Switching to AUTO select\n",
mitigation_options[i].option);
return SPECTRE_V2_CMD_AUTO;
}
if (cmd == SPECTRE_V2_CMD_IBRS && !boot_cpu_has(X86_FEATURE_IBRS)) {
pr_err("%s selected but CPU doesn't have IBRS. Switching to AUTO select\n",
mitigation_options[i].option);
return SPECTRE_V2_CMD_AUTO;
}
if (cmd == SPECTRE_V2_CMD_IBRS && cpu_feature_enabled(X86_FEATURE_XENPV)) {
pr_err("%s selected but running as XenPV guest. Switching to AUTO select\n",
mitigation_options[i].option);
return SPECTRE_V2_CMD_AUTO;
}
spec_v2_print_cond(mitigation_options[i].option,
mitigation_options[i].secure);
return cmd;
return 0;
}
early_param("spectre_v2", spectre_v2_parse_cmdline);
static enum spectre_v2_mitigation __init spectre_v2_select_retpoline(void)
{
@ -2332,7 +2272,50 @@ static void __init bhi_apply_mitigation(void)
static void __init spectre_v2_select_mitigation(void)
{
spectre_v2_cmd = spectre_v2_parse_cmdline();
if ((spectre_v2_cmd == SPECTRE_V2_CMD_RETPOLINE ||
spectre_v2_cmd == SPECTRE_V2_CMD_RETPOLINE_LFENCE ||
spectre_v2_cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC ||
spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS_LFENCE ||
spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS_RETPOLINE) &&
!IS_ENABLED(CONFIG_MITIGATION_RETPOLINE)) {
pr_err("RETPOLINE selected but not compiled in. Switching to AUTO select\n");
spectre_v2_cmd = SPECTRE_V2_CMD_AUTO;
}
if ((spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS ||
spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS_LFENCE ||
spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS_RETPOLINE) &&
!boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) {
pr_err("EIBRS selected but CPU doesn't have Enhanced or Automatic IBRS. Switching to AUTO select\n");
spectre_v2_cmd = SPECTRE_V2_CMD_AUTO;
}
if ((spectre_v2_cmd == SPECTRE_V2_CMD_RETPOLINE_LFENCE ||
spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS_LFENCE) &&
!boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) {
pr_err("LFENCE selected, but CPU doesn't have a serializing LFENCE. Switching to AUTO select\n");
spectre_v2_cmd = SPECTRE_V2_CMD_AUTO;
}
if (spectre_v2_cmd == SPECTRE_V2_CMD_IBRS && !IS_ENABLED(CONFIG_MITIGATION_IBRS_ENTRY)) {
pr_err("IBRS selected but not compiled in. Switching to AUTO select\n");
spectre_v2_cmd = SPECTRE_V2_CMD_AUTO;
}
if (spectre_v2_cmd == SPECTRE_V2_CMD_IBRS && boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) {
pr_err("IBRS selected but not Intel CPU. Switching to AUTO select\n");
spectre_v2_cmd = SPECTRE_V2_CMD_AUTO;
}
if (spectre_v2_cmd == SPECTRE_V2_CMD_IBRS && !boot_cpu_has(X86_FEATURE_IBRS)) {
pr_err("IBRS selected but CPU doesn't have IBRS. Switching to AUTO select\n");
spectre_v2_cmd = SPECTRE_V2_CMD_AUTO;
}
if (spectre_v2_cmd == SPECTRE_V2_CMD_IBRS && cpu_feature_enabled(X86_FEATURE_XENPV)) {
pr_err("IBRS selected but running as XenPV guest. Switching to AUTO select\n");
spectre_v2_cmd = SPECTRE_V2_CMD_AUTO;
}
if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2) &&
(spectre_v2_cmd == SPECTRE_V2_CMD_NONE || spectre_v2_cmd == SPECTRE_V2_CMD_AUTO))