[PATCH v2 20/20] s390: Report AEF features to sysfs

[Steffen Eiden]

Display various information about the Arm execution Facility (AEF) to
userspace. The files are located in /sys/firmware/aef/. Show if the
feature is available and usable for the host, which formats are
available, and how many arm vCPUS per guest are supported by the
machine. Additionally, provide the raw binary output of QAAF fc1 (Query
Model Capabilities) in the file qmc and fc2 (Initial
System-Registers-Save Area) in the file save_area.

Co-developed-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
Signed-off-by: Steffen Eiden <seiden@xxxxxxxxxxxxx>
---
 arch/s390/kernel/aef.c | 86 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)

diff --git a/arch/s390/kernel/aef.c b/arch/s390/kernel/aef.c
index 825e2643a892..2691f1ac63dc 100644
--- a/arch/s390/kernel/aef.c
+++ b/arch/s390/kernel/aef.c
@@ -40,6 +40,66 @@ const struct aef_info *aef_info(void)
 }
 EXPORT_SYMBOL(aef_info);
 
+static struct kset *aef_query_kset;
+static struct kobject *aef_kobj;
+
+#define aef_sysfs_qval_def(_name)					\
+	static ssize_t _name##_show(struct kobject *kobj,		\
+				    struct kobj_attribute *attr,	\
+				    char *buf)				\
+	{								\
+		return sysfs_emit(buf, "%lx\n", info._name);		\
+	}								\
+	static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
+
+#define aef_sysfs_qval_attr(_name) &_name##_attr.attr
+
+aef_sysfs_qval_def(arm_guest_supp);
+aef_sysfs_qval_def(sae_avail);
+aef_sysfs_qval_def(ptff_avail);
+aef_sysfs_qval_def(supp_state_desc_formats);
+aef_sysfs_qval_def(supp_save_area_formats);
+aef_sysfs_qval_def(max_num_vcpu);
+
+static ssize_t qmc_read(struct file *filp, struct kobject *kobj,
+			const struct bin_attribute *attr, char *buf, loff_t off,
+			size_t count)
+{
+	return memory_read_from_buffer(buf, count, &off, &qmc, sizeof(qmc));
+}
+
+BIN_ATTR_RO(qmc, sizeof(qmc));
+
+static ssize_t save_area_read(struct file *filp, struct kobject *kobj,
+			      const struct bin_attribute *attr, char *buf,
+			      loff_t off, size_t count)
+{
+	return memory_read_from_buffer(buf, count, &off, &save_area,
+				       sizeof(save_area));
+}
+
+BIN_ATTR_RO(save_area, sizeof(save_area));
+
+static struct attribute *aef_query_attrs[] = {
+	aef_sysfs_qval_attr(sae_avail),
+	aef_sysfs_qval_attr(ptff_avail),
+	aef_sysfs_qval_attr(supp_state_desc_formats),
+	aef_sysfs_qval_attr(supp_save_area_formats),
+	aef_sysfs_qval_attr(max_num_vcpu),
+	NULL,
+};
+
+static const struct bin_attribute *aef_query_bin_attrs[] = {
+	&bin_attr_qmc,
+	&bin_attr_save_area,
+	NULL,
+};
+
+static struct attribute_group aef_query_attr_group = {
+	.attrs = aef_query_attrs,
+	.bin_attrs = aef_query_bin_attrs,
+};
+
 static int __init aef_init_save_area(void)
 {
 	int ret;
@@ -95,7 +155,33 @@ static int __init aef_sysfs_init(void)
 	if (rc)
 		return rc;
 
+	aef_kobj = kobject_create_and_add("aef", firmware_kobj);
+	if (!aef_kobj)
+		return -ENOMEM;
+
+	rc = sysfs_create_file(aef_kobj, aef_sysfs_qval_attr(arm_guest_supp));
+	if (rc)
+		goto out_kobj;
+
+	aef_query_kset = kset_create_and_add("query", NULL, aef_kobj);
+	if (!aef_query_kset)
+		goto out_arm_guest_supp;
+
+	rc = sysfs_create_group(&aef_query_kset->kobj, &aef_query_attr_group);
+	if (rc)
+		goto out_kset;
+
 	return 0;
+
+out_kset:
+	kset_unregister(aef_query_kset);
+out_arm_guest_supp:
+	sysfs_remove_file(aef_kobj, &arm_guest_supp_attr.attr);
+out_kobj:
+	kobject_del(aef_kobj);
+	kobject_put(aef_kobj);
+
+	return rc;
 }
 
 arch_initcall(aef_sysfs_init);
-- 
2.53.0