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>
(cherry picked from commit db366061fff1f76407cb5d1b0975fcc381400cc3)

Orabug: 29526900
CVE: CVE-2018-12126
CVE: CVE-2018-12130
CVE: CVE-2018-12127

Signed-off-by: Kanth Ghatraju <kanth.ghatraju@oracle.com>
Reviewed-by: Mihai Carabas <mihai.carabas@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Conflicts:
	The changes to arch/x86/kernel/cpu/bugs.c instead need to be made to
	arch/x86/kernel/cpu/bugs_64.c.
	X86_HYPER_NATIVE doesn't exist so just leave that change out.
	sched_smt_active() does not exist, instead use cpu_smp_control.
	hypervisor_is_type replaced with cpu_has_hypervisor

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 23348a84462d41aa1c861117c4199c4514a8af74..fdaf7e4d7dd6e4fdb4b3966fe03ee6a64c165f05 100644 (file)
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -278,6 +278,7 @@ 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_64.c b/arch/x86/kernel/cpu/bugs_64.c
index afc91d319b2216e0c226f895297c7034172097b8..7babe5d1c4b2f97b3adbfe1691f0f416c23ce147 100644 (file)
--- a/arch/x86/kernel/cpu/bugs_64.c
+++ b/arch/x86/kernel/cpu/bugs_64.c
@@ -1373,6 +1373,22 @@ static ssize_t l1tf_show_state(char *buf)
                       l1tf_vmx_states[l1tf_vmx_mitigation],
                       cpu_smt_control == CPU_SMT_ENABLED ? "vulnerable" : "disabled");
 }
+
+static ssize_t mds_show_state(char *buf)
+{
+       if (cpu_has_hypervisor) {
+               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],
+                       (cpu_smt_control == CPU_SMT_ENABLED) ? "mitigated" : "disabled");
+       }
+
+       return sprintf(buf, "%s; SMT %s\n", mds_strings[mds_mitigation],
+               (cpu_smt_control == CPU_SMT_ENABLED) ? "vulnerable" : "disabled");
+}
 #else
 static ssize_t l1tf_show_state(char *buf)
 {
@@ -1475,6 +1491,10 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr
                        return l1tf_show_state(buf);
                break;
 
+       case X86_BUG_MDS:
+               return mds_show_state(buf);
+               break;
+
        default:
                break;
        }
@@ -1510,4 +1530,9 @@ 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 e495e904c0261ac6d341019cb07f63afc2f37d37..adb1315b21ab5f289fdba4bf514bab6bd92fffe6 100644 (file)
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -501,11 +501,18 @@ 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,
@@ -513,6 +520,7 @@ 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 20f0013a719e2d73aa071a2de2effa55305f99a9..00ddb1b5d0ba89c9130617e1cf50773845b92792 100644 (file)
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -50,6 +50,8 @@ 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 struct device *cpu_device_create(struct device *parent, void *drvdata,
                                        const struct attribute_group **groups,