[mirror_ubuntu-bionic-kernel.git] / arch / x86 / kernel / cpu / bugs.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  Copyright (C) 1994  Linus Torvalds
 *
 *  Cyrix stuff, June 1998 by:
 *	- Rafael R. Reilova (moved everything from head.S),
 *        <rreilova@ececs.uc.edu>
 *	- Channing Corn (tests & fixes),
 *	- Andrew D. Balsa (code cleanup).
 */
#include <linux/init.h>
#include <linux/utsname.h>
#include <linux/cpu.h>
#include <linux/module.h>

#include <asm/nospec-branch.h>
#include <asm/cmdline.h>
#include <asm/bugs.h>
#include <asm/processor.h>
#include <asm/processor-flags.h>
#include <asm/fpu/internal.h>
#include <asm/msr.h>
#include <asm/paravirt.h>
#include <asm/alternative.h>
#include <asm/pgtable.h>
#include <asm/set_memory.h>
#include <asm/intel-family.h>

static void __init spectre_v2_select_mitigation(void);

void __init check_bugs(void)
{
	identify_boot_cpu();

	if (!IS_ENABLED(CONFIG_SMP)) {
		pr_info("CPU: ");
		print_cpu_info(&boot_cpu_data);
	}

	/* Select the proper spectre mitigation before patching alternatives */
	spectre_v2_select_mitigation();

#ifdef CONFIG_X86_32
	/*
	 * Check whether we are able to run this kernel safely on SMP.
	 *
	 * - i386 is no longer supported.
	 * - In order to run on anything without a TSC, we need to be
	 *   compiled for a i486.
	 */
	if (boot_cpu_data.x86 < 4)
		panic("Kernel requires i486+ for 'invlpg' and other features");

	init_utsname()->machine[1] =
		'0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
	alternative_instructions();

	fpu__init_check_bugs();
#else /* CONFIG_X86_64 */
	alternative_instructions();

	/*
	 * Make sure the first 2MB area is not mapped by huge pages
	 * There are typically fixed size MTRRs in there and overlapping
	 * MTRRs into large pages causes slow downs.
	 *
	 * Right now we don't do that with gbpages because there seems
	 * very little benefit for that case.
	 */
	if (!direct_gbpages)
		set_memory_4k((unsigned long)__va(0), 1);
#endif
}

/* The kernel command line selection */
enum spectre_v2_mitigation_cmd {
	SPECTRE_V2_CMD_NONE,
	SPECTRE_V2_CMD_AUTO,
	SPECTRE_V2_CMD_FORCE,
	SPECTRE_V2_CMD_RETPOLINE,
	SPECTRE_V2_CMD_RETPOLINE_GENERIC,
	SPECTRE_V2_CMD_RETPOLINE_AMD,
};

static const char *spectre_v2_strings[] = {
	[SPECTRE_V2_NONE]			= "Vulnerable",
	[SPECTRE_V2_RETPOLINE_MINIMAL]		= "Vulnerable: Minimal generic ASM retpoline",
	[SPECTRE_V2_RETPOLINE_MINIMAL_AMD]	= "Vulnerable: Minimal AMD ASM retpoline",
	[SPECTRE_V2_RETPOLINE_GENERIC]		= "Mitigation: Full generic retpoline",
	[SPECTRE_V2_RETPOLINE_AMD]		= "Mitigation: Full AMD retpoline",
};

#undef pr_fmt
#define pr_fmt(fmt)     "Spectre V2 : " fmt

static enum spectre_v2_mitigation spectre_v2_enabled = SPECTRE_V2_NONE;

#ifdef RETPOLINE
static bool spectre_v2_bad_module;

bool retpoline_module_ok(bool has_retpoline)
{
	if (spectre_v2_enabled == SPECTRE_V2_NONE || has_retpoline)
		return true;

	pr_err("System may be vulnerable to spectre v2\n");
	spectre_v2_bad_module = true;
	return false;
}

static inline const char *spectre_v2_module_string(void)
{
	return spectre_v2_bad_module ? " - vulnerable module loaded" : "";
}
#else
static inline const char *spectre_v2_module_string(void) { return ""; }
#endif

static void __init spec2_print_if_insecure(const char *reason)
{
	if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
		pr_info("%s\n", reason);
}

static void __init spec2_print_if_secure(const char *reason)
{
	if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
		pr_info("%s\n", reason);
}

static inline bool retp_compiler(void)
{
	return __is_defined(RETPOLINE);
}

static inline bool match_option(const char *arg, int arglen, const char *opt)
{
	int len = strlen(opt);

	return len == arglen && !strncmp(arg, opt, len);
}

static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
{
	char arg[20];
	int ret;

	ret = cmdline_find_option(boot_command_line, "spectre_v2", arg,
				  sizeof(arg));
	if (ret > 0)  {
		if (match_option(arg, ret, "off")) {
			goto disable;
		} else if (match_option(arg, ret, "on")) {
			spec2_print_if_secure("force enabled on command line.");
			return SPECTRE_V2_CMD_FORCE;
		} else if (match_option(arg, ret, "retpoline")) {
			spec2_print_if_insecure("retpoline selected on command line.");
			return SPECTRE_V2_CMD_RETPOLINE;
		} else if (match_option(arg, ret, "retpoline,amd")) {
			if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD) {
				pr_err("retpoline,amd selected but CPU is not AMD. Switching to AUTO select\n");
				return SPECTRE_V2_CMD_AUTO;
			}
			spec2_print_if_insecure("AMD retpoline selected on command line.");
			return SPECTRE_V2_CMD_RETPOLINE_AMD;
		} else if (match_option(arg, ret, "retpoline,generic")) {
			spec2_print_if_insecure("generic retpoline selected on command line.");
			return SPECTRE_V2_CMD_RETPOLINE_GENERIC;
		} else if (match_option(arg, ret, "auto")) {
			return SPECTRE_V2_CMD_AUTO;
		}
	}

	if (!cmdline_find_option_bool(boot_command_line, "nospectre_v2"))
		return SPECTRE_V2_CMD_AUTO;
disable:
	spec2_print_if_insecure("disabled on command line.");
	return SPECTRE_V2_CMD_NONE;
}

/* Check for Skylake-like CPUs (for RSB handling) */
static bool __init is_skylake_era(void)
{
	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
	    boot_cpu_data.x86 == 6) {
		switch (boot_cpu_data.x86_model) {
		case INTEL_FAM6_SKYLAKE_MOBILE:
		case INTEL_FAM6_SKYLAKE_DESKTOP:
		case INTEL_FAM6_SKYLAKE_X:
		case INTEL_FAM6_KABYLAKE_MOBILE:
		case INTEL_FAM6_KABYLAKE_DESKTOP:
			return true;
		}
	}
	return false;
}

static void __init spectre_v2_select_mitigation(void)
{
	enum spectre_v2_mitigation_cmd cmd = spectre_v2_parse_cmdline();
	enum spectre_v2_mitigation mode = SPECTRE_V2_NONE;

	/*
	 * If the CPU is not affected and the command line mode is NONE or AUTO
	 * then nothing to do.
	 */
	if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2) &&
	    (cmd == SPECTRE_V2_CMD_NONE || cmd == SPECTRE_V2_CMD_AUTO))
		return;

	switch (cmd) {
	case SPECTRE_V2_CMD_NONE:
		return;

	case SPECTRE_V2_CMD_FORCE:
	case SPECTRE_V2_CMD_AUTO:
		if (IS_ENABLED(CONFIG_RETPOLINE))
			goto retpoline_auto;
		break;
	case SPECTRE_V2_CMD_RETPOLINE_AMD:
		if (IS_ENABLED(CONFIG_RETPOLINE))
			goto retpoline_amd;
		break;
	case SPECTRE_V2_CMD_RETPOLINE_GENERIC:
		if (IS_ENABLED(CONFIG_RETPOLINE))
			goto retpoline_generic;
		break;
	case SPECTRE_V2_CMD_RETPOLINE:
		if (IS_ENABLED(CONFIG_RETPOLINE))
			goto retpoline_auto;
		break;
	}
	pr_err("kernel not compiled with retpoline; no mitigation available!");
	return;

retpoline_auto:
	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
	retpoline_amd:
		if (!boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) {
			pr_err("LFENCE not serializing. Switching to generic retpoline\n");
			goto retpoline_generic;
		}
		mode = retp_compiler() ? SPECTRE_V2_RETPOLINE_AMD :
					 SPECTRE_V2_RETPOLINE_MINIMAL_AMD;
		setup_force_cpu_cap(X86_FEATURE_RETPOLINE_AMD);
		setup_force_cpu_cap(X86_FEATURE_RETPOLINE);
	} else {
	retpoline_generic:
		mode = retp_compiler() ? SPECTRE_V2_RETPOLINE_GENERIC :
					 SPECTRE_V2_RETPOLINE_MINIMAL;
		setup_force_cpu_cap(X86_FEATURE_RETPOLINE);
	}

	spectre_v2_enabled = mode;
	pr_info("%s\n", spectre_v2_strings[mode]);

	/*
	 * If neither SMEP or KPTI are available, there is a risk of
	 * hitting userspace addresses in the RSB after a context switch
	 * from a shallow call stack to a deeper one. To prevent this fill
	 * the entire RSB, even when using IBRS.
	 *
	 * Skylake era CPUs have a separate issue with *underflow* of the
	 * RSB, when they will predict 'ret' targets from the generic BTB.
	 * The proper mitigation for this is IBRS. If IBRS is not supported
	 * or deactivated in favour of retpolines the RSB fill on context
	 * switch is required.
	 */
	if ((!boot_cpu_has(X86_FEATURE_PTI) &&
	     !boot_cpu_has(X86_FEATURE_SMEP)) || is_skylake_era()) {
		setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW);
		pr_info("Filling RSB on context switch\n");
	}

	/* Initialize Indirect Branch Prediction Barrier if supported */
	if (boot_cpu_has(X86_FEATURE_IBPB)) {
		setup_force_cpu_cap(X86_FEATURE_USE_IBPB);
		pr_info("Enabling Indirect Branch Prediction Barrier\n");
	}
}

#undef pr_fmt

#ifdef CONFIG_SYSFS
ssize_t cpu_show_meltdown(struct device *dev,
			  struct device_attribute *attr, char *buf)
{
	if (!boot_cpu_has_bug(X86_BUG_CPU_MELTDOWN))
		return sprintf(buf, "Not affected\n");
	if (boot_cpu_has(X86_FEATURE_PTI))
		return sprintf(buf, "Mitigation: PTI\n");
	return sprintf(buf, "Vulnerable\n");
}

ssize_t cpu_show_spectre_v1(struct device *dev,
			    struct device_attribute *attr, char *buf)
{
	if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V1))
		return sprintf(buf, "Not affected\n");
	return sprintf(buf, "Mitigation: __user pointer sanitization\n");
}

ssize_t cpu_show_spectre_v2(struct device *dev,
			    struct device_attribute *attr, char *buf)
{
	if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
		return sprintf(buf, "Not affected\n");

	return sprintf(buf, "%s%s%s\n", spectre_v2_strings[spectre_v2_enabled],
		       boot_cpu_has(X86_FEATURE_USE_IBPB) ? ", IBPB" : "",
		       spectre_v2_module_string());
}
#endif

void __ibp_barrier(void)
{
	__wrmsr(MSR_IA32_PRED_CMD, PRED_CMD_IBPB, 0);
}
EXPORT_SYMBOL_GPL(__ibp_barrier);
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
1353ebb4	2	/*
1353ebb4 JF	3	* Copyright (C) 1994 Linus Torvalds
	4	*
	5	* Cyrix stuff, June 1998 by:
	6	* - Rafael R. Reilova (moved everything from head.S),
	7	* <rreilova@ececs.uc.edu>
	8	* - Channing Corn (tests & fixes),
	9	* - Andrew D. Balsa (code cleanup).
	10	*/
	11	#include <linux/init.h>
	12	#include <linux/utsname.h>
61dc0f55	13	#include <linux/cpu.h>
d280282b	14	#include <linux/module.h>
da285121 DW	15
	16	#include <asm/nospec-branch.h>
	17	#include <asm/cmdline.h>
91eb1b79	18	#include <asm/bugs.h>
1353ebb4	19	#include <asm/processor.h>
7ebad705	20	#include <asm/processor-flags.h>
952f07ec	21	#include <asm/fpu/internal.h>
1353ebb4 JF	22	#include <asm/msr.h>
	23	#include <asm/paravirt.h>
	24	#include <asm/alternative.h>
62a67e12	25	#include <asm/pgtable.h>
d1163651	26	#include <asm/set_memory.h>
c995efd5	27	#include <asm/intel-family.h>
1353ebb4	28
da285121 DW	29	static void __init spectre_v2_select_mitigation(void);
da285121 DW	30
1353ebb4 JF	31	void __init check_bugs(void)
	32	{
	33	identify_boot_cpu();
55a36b65	34
62a67e12 BP	35	if (!IS_ENABLED(CONFIG_SMP)) {
	36	pr_info("CPU: ");
	37	print_cpu_info(&boot_cpu_data);
	38	}
	39
da285121 DW	40	/* Select the proper spectre mitigation before patching alternatives */
	41	spectre_v2_select_mitigation();
	42
62a67e12	43	#ifdef CONFIG_X86_32
55a36b65 BP	44	/*
	45	* Check whether we are able to run this kernel safely on SMP.
	46	*
	47	* - i386 is no longer supported.
	48	* - In order to run on anything without a TSC, we need to be
	49	* compiled for a i486.
	50	*/
	51	if (boot_cpu_data.x86 < 4)
	52	panic("Kernel requires i486+ for 'invlpg' and other features");
	53
bfe4bb15 MV	54	init_utsname()->machine[1] =
bfe4bb15 MV	55	'0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
1353ebb4	56	alternative_instructions();
304bceda	57
4d164092	58	fpu__init_check_bugs();
62a67e12 BP	59	#else /* CONFIG_X86_64 */
	60	alternative_instructions();
	61
	62	/*
	63	* Make sure the first 2MB area is not mapped by huge pages
	64	* There are typically fixed size MTRRs in there and overlapping
	65	* MTRRs into large pages causes slow downs.
	66	*
	67	* Right now we don't do that with gbpages because there seems
	68	* very little benefit for that case.
	69	*/
	70	if (!direct_gbpages)
	71	set_memory_4k((unsigned long)__va(0), 1);
	72	#endif
1353ebb4	73	}
61dc0f55	74
da285121 DW	75	/* The kernel command line selection */
	76	enum spectre_v2_mitigation_cmd {
	77	SPECTRE_V2_CMD_NONE,
	78	SPECTRE_V2_CMD_AUTO,
	79	SPECTRE_V2_CMD_FORCE,
	80	SPECTRE_V2_CMD_RETPOLINE,
	81	SPECTRE_V2_CMD_RETPOLINE_GENERIC,
	82	SPECTRE_V2_CMD_RETPOLINE_AMD,
	83	};
	84
	85	static const char *spectre_v2_strings[] = {
	86	[SPECTRE_V2_NONE] = "Vulnerable",
	87	[SPECTRE_V2_RETPOLINE_MINIMAL] = "Vulnerable: Minimal generic ASM retpoline",
	88	[SPECTRE_V2_RETPOLINE_MINIMAL_AMD] = "Vulnerable: Minimal AMD ASM retpoline",
	89	[SPECTRE_V2_RETPOLINE_GENERIC] = "Mitigation: Full generic retpoline",
	90	[SPECTRE_V2_RETPOLINE_AMD] = "Mitigation: Full AMD retpoline",
	91	};
	92
	93	#undef pr_fmt
bbb5e08b	94	#define pr_fmt(fmt) "Spectre V2 : " fmt
da285121 DW	95
da285121 DW	96	static enum spectre_v2_mitigation spectre_v2_enabled = SPECTRE_V2_NONE;
d280282b AK	97
d280282b AK	98	#ifdef RETPOLINE
bb3c2578 TG	99	static bool spectre_v2_bad_module;
bb3c2578 TG	100
d280282b AK	101	bool retpoline_module_ok(bool has_retpoline)
	102	{
	103	if (spectre_v2_enabled == SPECTRE_V2_NONE \|\| has_retpoline)
	104	return true;
	105
c8b8e109	106	pr_err("System may be vulnerable to spectre v2\n");
d280282b AK	107	spectre_v2_bad_module = true;
	108	return false;
	109	}
bb3c2578 TG	110
	111	static inline const char *spectre_v2_module_string(void)
	112	{
	113	return spectre_v2_bad_module ? " - vulnerable module loaded" : "";
	114	}
	115	#else
	116	static inline const char *spectre_v2_module_string(void) { return ""; }
d280282b	117	#endif
da285121 DW	118
	119	static void __init spec2_print_if_insecure(const char *reason)
	120	{
	121	if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
	122	pr_info("%s\n", reason);
	123	}
	124
	125	static void __init spec2_print_if_secure(const char *reason)
	126	{
	127	if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
	128	pr_info("%s\n", reason);
	129	}
	130
	131	static inline bool retp_compiler(void)
	132	{
	133	return __is_defined(RETPOLINE);
	134	}
	135
	136	static inline bool match_option(const char arg, int arglen, const char opt)
	137	{
	138	int len = strlen(opt);
	139
	140	return len == arglen && !strncmp(arg, opt, len);
	141	}
	142
	143	static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
	144	{
	145	char arg[20];
	146	int ret;
	147
	148	ret = cmdline_find_option(boot_command_line, "spectre_v2", arg,
	149	sizeof(arg));
	150	if (ret > 0) {
	151	if (match_option(arg, ret, "off")) {
	152	goto disable;
	153	} else if (match_option(arg, ret, "on")) {
	154	spec2_print_if_secure("force enabled on command line.");
	155	return SPECTRE_V2_CMD_FORCE;
	156	} else if (match_option(arg, ret, "retpoline")) {
	157	spec2_print_if_insecure("retpoline selected on command line.");
	158	return SPECTRE_V2_CMD_RETPOLINE;
	159	} else if (match_option(arg, ret, "retpoline,amd")) {
	160	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD) {
	161	pr_err("retpoline,amd selected but CPU is not AMD. Switching to AUTO select\n");
	162	return SPECTRE_V2_CMD_AUTO;
	163	}
	164	spec2_print_if_insecure("AMD retpoline selected on command line.");
	165	return SPECTRE_V2_CMD_RETPOLINE_AMD;
	166	} else if (match_option(arg, ret, "retpoline,generic")) {
	167	spec2_print_if_insecure("generic retpoline selected on command line.");
	168	return SPECTRE_V2_CMD_RETPOLINE_GENERIC;
	169	} else if (match_option(arg, ret, "auto")) {
	170	return SPECTRE_V2_CMD_AUTO;
	171	}
	172	}
	173
	174	if (!cmdline_find_option_bool(boot_command_line, "nospectre_v2"))
	175	return SPECTRE_V2_CMD_AUTO;
	176	disable:
	177	spec2_print_if_insecure("disabled on command line.");
	178	return SPECTRE_V2_CMD_NONE;
	179	}
	180
c995efd5 DW	181	/* Check for Skylake-like CPUs (for RSB handling) */
	182	static bool __init is_skylake_era(void)
	183	{
	184	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
	185	boot_cpu_data.x86 == 6) {
	186	switch (boot_cpu_data.x86_model) {
	187	case INTEL_FAM6_SKYLAKE_MOBILE:
	188	case INTEL_FAM6_SKYLAKE_DESKTOP:
	189	case INTEL_FAM6_SKYLAKE_X:
	190	case INTEL_FAM6_KABYLAKE_MOBILE:
	191	case INTEL_FAM6_KABYLAKE_DESKTOP:
	192	return true;
	193	}
	194	}
	195	return false;
	196	}
	197
da285121 DW	198	static void __init spectre_v2_select_mitigation(void)
	199	{
	200	enum spectre_v2_mitigation_cmd cmd = spectre_v2_parse_cmdline();
	201	enum spectre_v2_mitigation mode = SPECTRE_V2_NONE;
	202
	203	/*
	204	* If the CPU is not affected and the command line mode is NONE or AUTO
	205	* then nothing to do.
	206	*/
	207	if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2) &&
	208	(cmd == SPECTRE_V2_CMD_NONE \|\| cmd == SPECTRE_V2_CMD_AUTO))
	209	return;
	210
	211	switch (cmd) {
	212	case SPECTRE_V2_CMD_NONE:
	213	return;
	214
	215	case SPECTRE_V2_CMD_FORCE:
da285121	216	case SPECTRE_V2_CMD_AUTO:
d0f293e0 DL	217	if (IS_ENABLED(CONFIG_RETPOLINE))
	218	goto retpoline_auto;
	219	break;
da285121 DW	220	case SPECTRE_V2_CMD_RETPOLINE_AMD:
	221	if (IS_ENABLED(CONFIG_RETPOLINE))
	222	goto retpoline_amd;
	223	break;
	224	case SPECTRE_V2_CMD_RETPOLINE_GENERIC:
	225	if (IS_ENABLED(CONFIG_RETPOLINE))
	226	goto retpoline_generic;
	227	break;
	228	case SPECTRE_V2_CMD_RETPOLINE:
	229	if (IS_ENABLED(CONFIG_RETPOLINE))
	230	goto retpoline_auto;
	231	break;
	232	}
	233	pr_err("kernel not compiled with retpoline; no mitigation available!");
	234	return;
	235
	236	retpoline_auto:
	237	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
	238	retpoline_amd:
	239	if (!boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) {
	240	pr_err("LFENCE not serializing. Switching to generic retpoline\n");
	241	goto retpoline_generic;
	242	}
	243	mode = retp_compiler() ? SPECTRE_V2_RETPOLINE_AMD :
	244	SPECTRE_V2_RETPOLINE_MINIMAL_AMD;
	245	setup_force_cpu_cap(X86_FEATURE_RETPOLINE_AMD);
	246	setup_force_cpu_cap(X86_FEATURE_RETPOLINE);
	247	} else {
	248	retpoline_generic:
	249	mode = retp_compiler() ? SPECTRE_V2_RETPOLINE_GENERIC :
	250	SPECTRE_V2_RETPOLINE_MINIMAL;
	251	setup_force_cpu_cap(X86_FEATURE_RETPOLINE);
	252	}
	253
	254	spectre_v2_enabled = mode;
	255	pr_info("%s\n", spectre_v2_strings[mode]);
c995efd5 DW	256
	257	/*
	258	* If neither SMEP or KPTI are available, there is a risk of
	259	* hitting userspace addresses in the RSB after a context switch
	260	* from a shallow call stack to a deeper one. To prevent this fill
	261	* the entire RSB, even when using IBRS.
	262	*
	263	* Skylake era CPUs have a separate issue with underflow of the
	264	* RSB, when they will predict 'ret' targets from the generic BTB.
	265	* The proper mitigation for this is IBRS. If IBRS is not supported
	266	* or deactivated in favour of retpolines the RSB fill on context
	267	* switch is required.
	268	*/
	269	if ((!boot_cpu_has(X86_FEATURE_PTI) &&
	270	!boot_cpu_has(X86_FEATURE_SMEP)) \|\| is_skylake_era()) {
	271	setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW);
	272	pr_info("Filling RSB on context switch\n");
	273	}
bd12e896 DW	274
bd12e896 DW	275	/* Initialize Indirect Branch Prediction Barrier if supported */
581abf91 DW	276	if (boot_cpu_has(X86_FEATURE_IBPB)) {
581abf91 DW	277	setup_force_cpu_cap(X86_FEATURE_USE_IBPB);
bd12e896 DW	278	pr_info("Enabling Indirect Branch Prediction Barrier\n");
bd12e896 DW	279	}
da285121 DW	280	}
	281
	282	#undef pr_fmt
	283
61dc0f55 TG	284	#ifdef CONFIG_SYSFS
	285	ssize_t cpu_show_meltdown(struct device *dev,
	286	struct device_attribute attr, char buf)
	287	{
	288	if (!boot_cpu_has_bug(X86_BUG_CPU_MELTDOWN))
	289	return sprintf(buf, "Not affected\n");
	290	if (boot_cpu_has(X86_FEATURE_PTI))
	291	return sprintf(buf, "Mitigation: PTI\n");
	292	return sprintf(buf, "Vulnerable\n");
	293	}
	294
	295	ssize_t cpu_show_spectre_v1(struct device *dev,
	296	struct device_attribute attr, char buf)
	297	{
	298	if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V1))
	299	return sprintf(buf, "Not affected\n");
f7d07951	300	return sprintf(buf, "Mitigation: __user pointer sanitization\n");
61dc0f55 TG	301	}
	302
	303	ssize_t cpu_show_spectre_v2(struct device *dev,
	304	struct device_attribute attr, char buf)
	305	{
	306	if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
	307	return sprintf(buf, "Not affected\n");
da285121	308
bd12e896	309	return sprintf(buf, "%s%s%s\n", spectre_v2_strings[spectre_v2_enabled],
581abf91	310	boot_cpu_has(X86_FEATURE_USE_IBPB) ? ", IBPB" : "",
bb3c2578	311	spectre_v2_module_string());
61dc0f55 TG	312	}
61dc0f55 TG	313	#endif
26197022 BP	314
	315	void __ibp_barrier(void)
	316	{
	317	__wrmsr(MSR_IA32_PRED_CMD, PRED_CMD_IBPB, 0);
	318	}
	319	EXPORT_SYMBOL_GPL(__ibp_barrier);