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 5abe1cc9f0682128d5e3a648d449aa91015ea071..ea6934ab945b0c4e300836b4b4496d368ed84043 100644 (file)
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -384,6 +384,7 @@ 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 08af65b69f9163e756e4184149b5704a733029c6..0b07c79ed881459b049058b20bbcdf1f1f583829 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))
@@ -1905,6 +1919,9 @@ 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;
        }
@@ -1956,4 +1973,9 @@ 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 c800de86200dbb6f6685dd04533a19a5295839a9..ba4e7732e2c70ea8825a1a90d15463d58cc7e44d 100644 (file)
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -558,6 +558,12 @@ 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);
@@ -567,6 +573,7 @@ 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,
@@ -578,6 +585,7 @@ 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 df645f1c48d35166493ab2f51baeb9419748c175..f958ecc82de99a623db6f229079892f46c4b628c 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,