x86/speculation/mmio: Add sysfs reporting for Processor MMIO Stale Data

commit 8d50cdf8b8341770bc6367bce40c0c1bb0e1d5b3 upstream

Add the sysfs reporting file for Processor MMIO Stale Data
vulnerability. It exposes the vulnerability and mitigation state similar
to the existing files for the other hardware vulnerabilities.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.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 b9c14c11efc58f6de918795340d24f6b769eb5e6..dee993602c313dccf53f71f21d91583da4a6e5de 100644 (file)
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -481,6 +481,7 @@ What:               /sys/devices/system/cpu/vulnerabilities
                /sys/devices/system/cpu/vulnerabilities/srbds
                /sys/devices/system/cpu/vulnerabilities/tsx_async_abort
                /sys/devices/system/cpu/vulnerabilities/itlb_multihit
+               /sys/devices/system/cpu/vulnerabilities/mmio_stale_data
 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 4a5b1ad8a4e4d9938d4bf0ec7997d7966e0d0971..7e51ee81f85aca0045104f9a419d8fb7b91e9ad3 100644 (file)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1808,6 +1808,20 @@ static ssize_t tsx_async_abort_show_state(char *buf)
                       sched_smt_active() ? "vulnerable" : "disabled");
 }
 
+static ssize_t mmio_stale_data_show_state(char *buf)
+{
+       if (mmio_mitigation == MMIO_MITIGATION_OFF)
+               return sysfs_emit(buf, "%s\n", mmio_strings[mmio_mitigation]);
+
+       if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
+               return sysfs_emit(buf, "%s; SMT Host state unknown\n",
+                                 mmio_strings[mmio_mitigation]);
+       }
+
+       return sysfs_emit(buf, "%s; SMT %s\n", mmio_strings[mmio_mitigation],
+                         sched_smt_active() ? "vulnerable" : "disabled");
+}
+
 static char *stibp_state(void)
 {
        if (spectre_v2_in_eibrs_mode(spectre_v2_enabled))
@@ -1908,6 +1922,9 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr
        case X86_BUG_SRBDS:
                return srbds_show_state(buf);
 
+       case X86_BUG_MMIO_STALE_DATA:
+               return mmio_stale_data_show_state(buf);
+
        default:
                break;
        }
@@ -1959,4 +1976,9 @@ ssize_t cpu_show_srbds(struct device *dev, struct device_attribute *attr, char *
 {
        return cpu_show_common(dev, attr, buf, X86_BUG_SRBDS);
 }
+
+ssize_t cpu_show_mmio_stale_data(struct device *dev, struct device_attribute *attr, char *buf)
+{
+       return cpu_show_common(dev, attr, buf, X86_BUG_MMIO_STALE_DATA);
+}
 #endif

diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 1df0574861768df02cbd86d89f39528eea965c61..cd204be1f4b7da52ac49a6ccc7661ed8bc40a363 100644 (file)
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -571,6 +571,12 @@ ssize_t __weak cpu_show_srbds(struct device *dev,
        return sprintf(buf, "Not affected\n");
 }
 
+ssize_t __weak cpu_show_mmio_stale_data(struct device *dev,
+                                       struct device_attribute *attr, char *buf)
+{
+       return sysfs_emit(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);
@@ -580,6 +586,7 @@ static DEVICE_ATTR(mds, 0444, cpu_show_mds, NULL);
 static DEVICE_ATTR(tsx_async_abort, 0444, cpu_show_tsx_async_abort, NULL);
 static DEVICE_ATTR(itlb_multihit, 0444, cpu_show_itlb_multihit, NULL);
 static DEVICE_ATTR(srbds, 0444, cpu_show_srbds, NULL);
+static DEVICE_ATTR(mmio_stale_data, 0444, cpu_show_mmio_stale_data, NULL);
 
 static struct attribute *cpu_root_vulnerabilities_attrs[] = {
        &dev_attr_meltdown.attr,
@@ -591,6 +598,7 @@ static struct attribute *cpu_root_vulnerabilities_attrs[] = {
        &dev_attr_tsx_async_abort.attr,
        &dev_attr_itlb_multihit.attr,
        &dev_attr_srbds.attr,
+       &dev_attr_mmio_stale_data.attr,
        NULL
 };
 

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index bf0587b05233bf6cee7ee7d5a3f58674a1232cf7..8cc06e1d4fc24fa7ad6f7a45e006c3c94597e66b 100644 (file)
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -65,6 +65,9 @@ extern ssize_t cpu_show_tsx_async_abort(struct device *dev,
 extern ssize_t cpu_show_itlb_multihit(struct device *dev,
                                      struct device_attribute *attr, char *buf);
 extern ssize_t cpu_show_srbds(struct device *dev, struct device_attribute *attr, char *buf);
+extern ssize_t cpu_show_mmio_stale_data(struct device *dev,
+                                       struct device_attribute *attr,
+                                       char *buf);
 
 extern __printf(4, 5)
 struct device *cpu_device_create(struct device *parent, void *drvdata,