Commit 9a9f8147 authored by David Kaplan's avatar David Kaplan Committed by Borislav Petkov (AMD)
Browse files

x86/bugs: Use early_param() for spectre_v2 



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: default avatarDavid Kaplan <david.kaplan@amd.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: default avatarPawan Gupta <pawan.kumar.gupta@linux.intel.com>
Link: https://lore.kernel.org/r/20250819192200.2003074-3-david.kaplan@amd.com
parent 8edb9e77

arch/x86/kernel/cpu/bugs.c

+82 −99
Original line number Diff line number Diff line
@@ -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;



	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;



	ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, sizeof(arg));

	if (ret < 0)

		return cmd;



	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 (!str)

		return -EINVAL;



	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 (nospectre_v2)

		return 0;



	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;

	}

	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);



	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))