x86/speculation/mds: Add sysfs reporting for MDS

commit 8a4b06d391b0a42a373808979b5028f5c84d9c6a upstream

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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 d75d1e29edd7216c4c989f03fa11f2a01943f92c..d1f5cb3980f4947cef856ec1547f16ea1148bb61 100644 (file)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1184,6 +1184,22 @@ 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)
@@ -1250,6 +1266,10 @@ 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;
        }
@@ -1281,4 +1301,9 @@ 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 668139cfa664084239136650f1488f995e55760b..cc37511de866590ed621a1ea0d49fdb255f2d31f 100644 (file)
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -548,11 +548,18 @@ 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,
@@ -560,6 +567,7 @@ 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,