From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>

Date: Thu, 19 May 2022 20:32:13 -0700

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

Git-commit: 8d50cdf8b8341770bc6367bce40c0c1bb0e1d5b3

Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git

Patch-mainline: Queued in tip for v5.19

References: bsc#1199650 CVE-2022-21166 CVE-2022-21127 CVE-2022-21123 CVE-2022-21125 CVE-2022-21180

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>

---

 Documentation/ABI/testing/sysfs-devices-system-cpu |    1 

 arch/x86/kernel/cpu/bugs.c                         |   22 +++++++++++++++++++++

 drivers/base/cpu.c                                 |    8 +++++++

 include/linux/cpu.h                                |    3 ++

 4 files changed, 34 insertions(+)

--- a/arch/x86/kernel/cpu/bugs.c

+++ b/arch/x86/kernel/cpu/bugs.c

@@ -1828,6 +1828,20 @@ static ssize_t tsx_async_abort_show_stat

 		       sched_smt_active() ? "vulnerable" : "disabled");

 }

+static ssize_t mmio_stale_data_show_state(char *buf)

+{

+	if (mmio_mitigation == MMIO_MITIGATION_OFF)

+		return sprintf(buf, "%s\n", mmio_strings[mmio_mitigation]);

+

+	if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {

+		return sprintf(buf, "%s; SMT Host state unknown\n",

+				  mmio_strings[mmio_mitigation]);

+	}

+

+	return sprintf(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))

@@ -1928,6 +1942,9 @@ static ssize_t cpu_show_common(struct de

 	case X86_BUG_SRBDS:

 		return srbds_show_state(buf);

+	case X86_BUG_MMIO_STALE_DATA:

+		return mmio_stale_data_show_state(buf);

+

 	default:

 		break;

 	}

@@ -1979,4 +1996,9 @@ ssize_t cpu_show_srbds(struct device *de

 {

 	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

--- a/Documentation/ABI/testing/sysfs-devices-system-cpu

+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu

@@ -495,6 +495,7 @@ What:		/sys/devices/system/cpu/vulnerabi

 		/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

--- a/drivers/base/cpu.c

+++ b/drivers/base/cpu.c

@@ -573,6 +573,12 @@ ssize_t __weak cpu_show_srbds(struct 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 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);

@@ -582,6 +588,7 @@ static DEVICE_ATTR(mds, 0444, cpu_show_m

 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,

@@ -593,6 +600,7 @@ static struct attribute *cpu_root_vulner

 	&dev_attr_tsx_async_abort.attr,

 	&dev_attr_itlb_multihit.attr,

 	&dev_attr_srbds.attr,

+	&dev_attr_mmio_stale_data.attr,

 	NULL

 };

--- a/include/linux/cpu.h

+++ b/include/linux/cpu.h

@@ -64,6 +64,9 @@ extern ssize_t cpu_show_tsx_async_abort(

 					char *buf);

 extern ssize_t cpu_show_itlb_multihit(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,