Commit 8a4b06d3 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/speculation/mds: Add sysfs reporting for MDS 



Add the sysfs reporting file for MDS. It exposes the vulnerability and
mitigation state similar to the existing files for the other speculative
hardware vulnerabilities.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarJon Masters <jcm@redhat.com>
Tested-by: default avatarJon Masters <jcm@redhat.com>
parent bc124170

Documentation/ABI/testing/sysfs-devices-system-cpu

+1 −0
Original line number Diff line number Diff line
@@ -484,6 +484,7 @@ What: /sys/devices/system/cpu/vulnerabilities 
		/sys/devices/system/cpu/vulnerabilities/spectre_v2

		/sys/devices/system/cpu/vulnerabilities/spec_store_bypass

		/sys/devices/system/cpu/vulnerabilities/l1tf

		/sys/devices/system/cpu/vulnerabilities/mds

Date:		January 2018

Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>

Description:	Information about CPU vulnerabilities

arch/x86/kernel/cpu/bugs.c

+25 −0
Original line number Diff line number Diff line
@@ -1172,6 +1172,22 @@ static ssize_t l1tf_show_state(char *buf) 
}

#endif



static ssize_t mds_show_state(char *buf)

{

	if (!hypervisor_is_type(X86_HYPER_NATIVE)) {

		return sprintf(buf, "%s; SMT Host state unknown\n",

			       mds_strings[mds_mitigation]);

	}



	if (boot_cpu_has(X86_BUG_MSBDS_ONLY)) {

		return sprintf(buf, "%s; SMT %s\n", mds_strings[mds_mitigation],

			       sched_smt_active() ? "mitigated" : "disabled");

	}



	return sprintf(buf, "%s; SMT %s\n", mds_strings[mds_mitigation],

		       sched_smt_active() ? "vulnerable" : "disabled");

}



static char *stibp_state(void)

{

	if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
@@ -1238,6 +1254,10 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr 
		if (boot_cpu_has(X86_FEATURE_L1TF_PTEINV))

			return l1tf_show_state(buf);

		break;



	case X86_BUG_MDS:

		return mds_show_state(buf);



	default:

		break;

	}
@@ -1269,4 +1289,9 @@ ssize_t cpu_show_l1tf(struct device *dev, struct device_attribute *attr, char *b 
{

	return cpu_show_common(dev, attr, buf, X86_BUG_L1TF);

}



ssize_t cpu_show_mds(struct device *dev, struct device_attribute *attr, char *buf)

{

	return cpu_show_common(dev, attr, buf, X86_BUG_MDS);

}

#endif

drivers/base/cpu.c

+8 −0
Original line number Diff line number Diff line
@@ -546,11 +546,18 @@ ssize_t __weak cpu_show_l1tf(struct device *dev, 
	return sprintf(buf, "Not affected\n");

}



ssize_t __weak cpu_show_mds(struct device *dev,

			    struct device_attribute *attr, char *buf)

{

	return sprintf(buf, "Not affected\n");

}



static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL);

static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL);

static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL);

static DEVICE_ATTR(spec_store_bypass, 0444, cpu_show_spec_store_bypass, NULL);

static DEVICE_ATTR(l1tf, 0444, cpu_show_l1tf, NULL);

static DEVICE_ATTR(mds, 0444, cpu_show_mds, NULL);



static struct attribute *cpu_root_vulnerabilities_attrs[] = {

	&dev_attr_meltdown.attr,
@@ -558,6 +565,7 @@ static struct attribute *cpu_root_vulnerabilities_attrs[] = { 
	&dev_attr_spectre_v2.attr,

	&dev_attr_spec_store_bypass.attr,

	&dev_attr_l1tf.attr,

	&dev_attr_mds.attr,

	NULL

};

include/linux/cpu.h

+2 −0
Original line number Diff line number Diff line
@@ -57,6 +57,8 @@ extern ssize_t cpu_show_spec_store_bypass(struct device *dev, 
					  struct device_attribute *attr, char *buf);

extern ssize_t cpu_show_l1tf(struct device *dev,

			     struct device_attribute *attr, char *buf);

extern ssize_t cpu_show_mds(struct device *dev,

			    struct device_attribute *attr, char *buf);



extern __printf(4, 5)

struct device *cpu_device_create(struct device *parent, void *drvdata,