[PATCH v7 14/15] s390/vfio-ap: Add 'migratable' feature to sysfs 'features' attribute

[Anthony Krowiak <akrowiak@linux.ibm.com>]

Add the 'migratable' feature to the features provided by the sysfs
/sys/devices/vfio_ap/matrix/feature attribute to indicate that migration
of vfio devices is supported. Since live guest migration is not supported
for SE guests, the 'migratable' feature will not be included when the
feature attribute is displayed.

Signed-off-by: Anthony Krowiak <akrowiak@linux.ibm.com>
---
 drivers/s390/crypto/vfio_ap_drv.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
index 8e69ed286bb9..abfb34421d74 100644
--- a/drivers/s390/crypto/vfio_ap_drv.c
+++ b/drivers/s390/crypto/vfio_ap_drv.c
@@ -26,9 +26,21 @@ MODULE_LICENSE("GPL v2");
 struct ap_matrix_dev *matrix_dev;
 debug_info_t *vfio_ap_dbf_info;
 
+#define VFIO_AP_DRV_FEATURES	"guest_matrix hotplug ap_config migratable"
+#define SE_GUEST_FEATURES	"guest_matrix hotplug ap_config"
+
 static ssize_t features_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
-	return sysfs_emit(buf, "guest_matrix hotplug ap_config\n");
+	/*
+	 * If the system running is an SE guest, it will support a different
+	 * set of features; for example, it will not support live guest
+	 * migration
+	 */
+	if (ap_is_se_guest())
+		return sysfs_emit(buf, "%s\n", SE_GUEST_FEATURES);
+
+	/* Return all features supported by the vfio_ap device driver */
+	return sysfs_emit(buf, "%s\n", VFIO_AP_DRV_FEATURES);
 }
 static DEVICE_ATTR_RO(features);
 
-- 
2.53.0