platform/x86/intel/ifs: Add IFS sysfs interface

Implement sysfs interface to trigger ifs test for a specific cpu.
Additional interfaces related to checking the status of the
scan test and seeing the version of the loaded IFS binary
are also added.

The basic usage is as below.
   - To start test, for example on cpu5:
       echo 5 > /sys/devices/platform/intel_ifs/run_test
   - To see the status of the last test
       cat /sys/devices/platform/intel_ifs/status
   - To see the version of the loaded scan binary
       cat /sys/devices/platform/intel_ifs/image_version

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>
Co-developed-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220506225410.1652287-10-tony.luck@intel.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

4 files changed, 158 insertions, 1 deletions

diff --git a/drivers/platform/x86/intel/ifs/Makefile b/drivers/platform/x86/intel/ifs/Makefile
index cedcb103f860..30f035ef5581 100644
--- a/drivers/platform/x86/intel/ifs/Makefile
+++ b/drivers/platform/x86/intel/ifs/Makefile
@@ -1,3 +1,3 @@
 obj-$(CONFIG_INTEL_IFS)		+= intel_ifs.o
 
-intel_ifs-objs			:= core.o load.o runtest.o
+intel_ifs-objs			:= core.o load.o runtest.o sysfs.o
diff --git a/drivers/platform/x86/intel/ifs/core.c b/drivers/platform/x86/intel/ifs/core.c
index f62578dae8e9..27204e3d674d 100644
--- a/drivers/platform/x86/intel/ifs/core.c
+++ b/drivers/platform/x86/intel/ifs/core.c
@@ -3,6 +3,7 @@
 
 #include <linux/module.h>
 #include <linux/kdev_t.h>
+#include <linux/semaphore.h>
 
 #include <asm/cpu_device_id.h>
 
@@ -47,9 +48,13 @@ static int __init ifs_init(void)
 	if (rdmsrl_safe(MSR_INTEGRITY_CAPS, &msrval))
 		return -ENODEV;
 
+	ifs_device.misc.groups = ifs_get_groups();
+
 	if ((msrval & BIT(ifs_device.data.integrity_cap_bit)) &&
 	    !misc_register(&ifs_device.misc)) {
+		down(&ifs_sem);
 		ifs_load_firmware(ifs_device.misc.this_device);
+		up(&ifs_sem);
 		return 0;
 	}
 
diff --git a/drivers/platform/x86/intel/ifs/ifs.h b/drivers/platform/x86/intel/ifs/ifs.h
index b648cccda3ec..720bd18a5e91 100644
--- a/drivers/platform/x86/intel/ifs/ifs.h
+++ b/drivers/platform/x86/intel/ifs/ifs.h
@@ -117,5 +117,8 @@ static inline struct ifs_data *ifs_get_data(struct device *dev)
 
 void ifs_load_firmware(struct device *dev);
 int do_core_test(int cpu, struct device *dev);
+const struct attribute_group **ifs_get_groups(void);
+
+extern struct semaphore ifs_sem;
 
 #endif
diff --git a/drivers/platform/x86/intel/ifs/sysfs.c b/drivers/platform/x86/intel/ifs/sysfs.c
new file mode 100644
index 000000000000..37d8380d6fa8
--- /dev/null
+++ b/drivers/platform/x86/intel/ifs/sysfs.c
@@ -0,0 +1,149 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2022 Intel Corporation. */
+
+#include <linux/cpu.h>
+#include <linux/delay.h>
+#include <linux/fs.h>
+#include <linux/semaphore.h>
+#include <linux/slab.h>
+
+#include "ifs.h"
+
+/*
+ * Protects against simultaneous tests on multiple cores, or
+ * reloading can file while a test is in progress
+ */
+DEFINE_SEMAPHORE(ifs_sem);
+
+/*
+ * The sysfs interface to check additional details of last test
+ * cat /sys/devices/system/platform/ifs/details
+ */
+static ssize_t details_show(struct device *dev,
+			    struct device_attribute *attr,
+			    char *buf)
+{
+	struct ifs_data *ifsd = ifs_get_data(dev);
+
+	return sysfs_emit(buf, "%#llx\n", ifsd->scan_details);
+}
+
+static DEVICE_ATTR_RO(details);
+
+static const char * const status_msg[] = {
+	[SCAN_NOT_TESTED] = "untested",
+	[SCAN_TEST_PASS] = "pass",
+	[SCAN_TEST_FAIL] = "fail"
+};
+
+/*
+ * The sysfs interface to check the test status:
+ * To check the status of last test
+ * cat /sys/devices/platform/ifs/status
+ */
+static ssize_t status_show(struct device *dev,
+			   struct device_attribute *attr,
+			   char *buf)
+{
+	struct ifs_data *ifsd = ifs_get_data(dev);
+
+	return sysfs_emit(buf, "%s\n", status_msg[ifsd->status]);
+}
+
+static DEVICE_ATTR_RO(status);
+
+/*
+ * The sysfs interface for single core testing
+ * To start test, for example, cpu5
+ * echo 5 > /sys/devices/platform/ifs/run_test
+ * To check the result:
+ * cat /sys/devices/platform/ifs/result
+ * The sibling core gets tested at the same time.
+ */
+static ssize_t run_test_store(struct device *dev,
+			      struct device_attribute *attr,
+			      const char *buf, size_t count)
+{
+	struct ifs_data *ifsd = ifs_get_data(dev);
+	unsigned int cpu;
+	int rc;
+
+	rc = kstrtouint(buf, 0, &cpu);
+	if (rc < 0 || cpu >= nr_cpu_ids)
+		return -EINVAL;
+
+	if (down_interruptible(&ifs_sem))
+		return -EINTR;
+
+	if (!ifsd->loaded)
+		rc = -EPERM;
+	else
+		rc = do_core_test(cpu, dev);
+
+	up(&ifs_sem);
+
+	return rc ? rc : count;
+}
+
+static DEVICE_ATTR_WO(run_test);
+
+/*
+ * Reload the IFS image. When user wants to install new IFS image
+ */
+static ssize_t reload_store(struct device *dev,
+			    struct device_attribute *attr,
+			    const char *buf, size_t count)
+{
+	struct ifs_data *ifsd = ifs_get_data(dev);
+	bool res;
+
+
+	if (kstrtobool(buf, &res))
+		return -EINVAL;
+	if (!res)
+		return count;
+
+	if (down_interruptible(&ifs_sem))
+		return -EINTR;
+
+	ifs_load_firmware(dev);
+
+	up(&ifs_sem);
+
+	return ifsd->loaded ? count : -ENODEV;
+}
+
+static DEVICE_ATTR_WO(reload);
+
+/*
+ * Display currently loaded IFS image version.
+ */
+static ssize_t image_version_show(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	struct ifs_data *ifsd = ifs_get_data(dev);
+
+	if (!ifsd->loaded)
+		return sysfs_emit(buf, "%s\n", "none");
+	else
+		return sysfs_emit(buf, "%#x\n", ifsd->loaded_version);
+}
+
+static DEVICE_ATTR_RO(image_version);
+
+/* global scan sysfs attributes */
+static struct attribute *plat_ifs_attrs[] = {
+	&dev_attr_details.attr,
+	&dev_attr_status.attr,
+	&dev_attr_run_test.attr,
+	&dev_attr_reload.attr,
+	&dev_attr_image_version.attr,
+	NULL
+};
+
+ATTRIBUTE_GROUPS(plat_ifs);
+
+const struct attribute_group **ifs_get_groups(void)
+{
+	return plat_ifs_groups;
+}