[MODERATED] [PATCH 5/9] TAA 5

From: Pawan Gupta <[email protected]>
Subject: [PATCH 5/9] x86/speculation/taa: Add sysfs reporting for TSX Async
 Abort

Add the sysfs reporting file for TSX Async Abort. It exposes the
vulnerability and the mitigation state similar to the existing files for
the other hardware vulnerabilities.

Sysfs file path is:
/sys/devices/system/cpu/vulnerabilities/tsx_async_abort

Signed-off-by: Pawan Gupta <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Mark Gross <[email protected]>
Reviewed-by: Tony Luck <[email protected]>
Tested-by: Neelima Krishnan <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Kosina <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: x86-ml <[email protected]>
---
 arch/x86/kernel/cpu/bugs.c | 23 +++++++++++++++++++++++
 drivers/base/cpu.c         |  9 +++++++++
 include/linux/cpu.h        |  3 +++
 3 files changed, 35 insertions(+)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 6648e0fbed96..07a8f812cf66 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1438,6 +1438,21 @@ static ssize_t mds_show_state(char *buf)
 		       sched_smt_active() ? "vulnerable" : "disabled");
 }
 
+static ssize_t tsx_async_abort_show_state(char *buf)
+{
+	if ((taa_mitigation == TAA_MITIGATION_TSX_DISABLED) ||
+	    (taa_mitigation == TAA_MITIGATION_OFF))
+		return sprintf(buf, "%s\n", taa_strings[taa_mitigation]);
+
+	if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
+		return sprintf(buf, "%s; SMT Host state unknown\n",
+			       taa_strings[taa_mitigation]);
+	}
+
+	return sprintf(buf, "%s; SMT %s\n", taa_strings[taa_mitigation],
+		       sched_smt_active() ? "vulnerable" : "disabled");
+}
+
 static char *stibp_state(void)
 {
 	if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
@@ -1508,6 +1523,9 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr
 	case X86_BUG_MDS:
 		return mds_show_state(buf);
 
+	case X86_BUG_TAA:
+		return tsx_async_abort_show_state(buf);
+
 	default:
 		break;
 	}
@@ -1544,4 +1562,9 @@ ssize_t cpu_show_mds(struct device *dev, struct device_attribute *attr, char *bu
 {
 	return cpu_show_common(dev, attr, buf, X86_BUG_MDS);
 }
+
+ssize_t cpu_show_tsx_async_abort(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	return cpu_show_common(dev, attr, buf, X86_BUG_TAA);
+}
 #endif
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index cc37511de866..0fccd8c0312e 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -554,12 +554,20 @@ ssize_t __weak cpu_show_mds(struct device *dev,
 	return sprintf(buf, "Not affected\n");
 }
 
+ssize_t __weak cpu_show_tsx_async_abort(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 DEVICE_ATTR(tsx_async_abort, 0444, cpu_show_tsx_async_abort, NULL);
 
 static struct attribute *cpu_root_vulnerabilities_attrs[] = {
 	&dev_attr_meltdown.attr,
@@ -568,6 +576,7 @@ static struct attribute *cpu_root_vulnerabilities_attrs[] = {
 	&dev_attr_spec_store_bypass.attr,
 	&dev_attr_l1tf.attr,
 	&dev_attr_mds.attr,
+	&dev_attr_tsx_async_abort.attr,
 	NULL
 };
 
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index d0633ebdaa9c..f35369f79771 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -59,6 +59,9 @@ 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 ssize_t cpu_show_tsx_async_abort(struct device *dev,
+					struct device_attribute *attr,
+					char *buf);
 
 extern __printf(4, 5)
 struct device *cpu_device_create(struct device *parent, void *drvdata,
-- 
2.21.0