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>
Gbp-Pq: Topic bugfix/all/spec
Gbp-Pq: Name 0014-x86-speculation-mds-Add-sysfs-reporting-for-MDS.patch

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 73318225a3681b3473abe87d0fe1bb4c3447e7ed..02b7bb711214ac73f3560cdc7731a289d179e078 100644 (file)
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -477,6 +477,7 @@ 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 413a672f03a3a5d2c17f4fc0f940af62bd85fa07..50b7d2a980e8182af37cc59322b151d62d1b4173 100644 (file)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1154,6 +1154,22 @@ 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)
@@ -1218,6 +1234,10 @@ 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;
        }
@@ -1249,4 +1269,9 @@ 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,