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: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Jon Masters <jcm@redhat.com>
Tested-by: Jon Masters <jcm@redhat.com>

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 9605dbd4b5b59ecc251913b1b327e6031cfb875f..2db5c3407fd6b4fb7ca4d1e0580578c4bb6c1dcb 100644 (file)
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -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

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index c7b29d200d27fc163bc7a86988033beca13e028e..7ab16a6ed06441e2b6cb36f469d8f8ee562d199b 100644 (file)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -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

diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index eb9443d5bae1f8f6eb80632640b7c549f83e0043..2fd6ca1021c2baefd13ac02089aa10845eacab27 100644 (file)
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -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
 };
 

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 5041357d0297afdce8b5605970947b34f85e7205..3c87ad888ed37aedbac10dce2c6f4390353bb920 100644 (file)
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -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,