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

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>

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 2ad01cad7f1c8286530a7a959aaf655b990a6c98..bcc974d276dc4521367b3a12038526f1cc49e166 100644 (file)
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -526,6 +526,7 @@ 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 56d5dea5e1283aee24d511e51f151b7e86c69c24..38853077ca587792424a7158f94c56179a08dcde 100644 (file)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1902,6 +1902,20 @@ 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))
@@ -2002,6 +2016,9 @@ 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;
        }
@@ -2053,4 +2070,9 @@ 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 2ef23fce0860c5d780d41c3eb13e51ad6132da26..a97776ea9d99067bb53c21210a7818e7dae39897 100644 (file)
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -564,6 +564,12 @@ ssize_t __weak cpu_show_srbds(struct device *dev,
        return sysfs_emit(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);
@@ -573,6 +579,7 @@ 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,
@@ -584,6 +591,7 @@ 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 54dc2f9a2d56e9f43cac9ef4e30600152c2230fd..2c74773547444e6ab4eb185d8eb62f5e06c6fe65 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,