[RFC 15/19] s390/zcrypt: introduce ioctl access to VFIO AP Matrix driver

[Tony Krowiak <akrowiak@linux.vnet.ibm.com>]

Introduces ioctl access to the VFIO AP Matrix device driver
by implementing the VFIO_DEVICE_GET_INFO ioctl. This ioctl
provides the VFIO AP Matrix device driver information to the
guest machine.

Signed-off-by: Tony Krowiak <akrowiak@linux.vnet.ibm.com>
---
 drivers/s390/crypto/vfio_ap_matrix_ops.c |   43 ++++++++++++++++++++++++++++++
 include/uapi/linux/vfio.h                |    1 +
 2 files changed, 44 insertions(+), 0 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_matrix_ops.c b/drivers/s390/crypto/vfio_ap_matrix_ops.c
index fd36074..74ea8db 100644
--- a/drivers/s390/crypto/vfio_ap_matrix_ops.c
+++ b/drivers/s390/crypto/vfio_ap_matrix_ops.c
@@ -137,6 +137,48 @@ static void ap_matrix_mdev_release(struct mdev_device *mdev)
 				 &matrix_mdev->group_notifier);
 }
 
+static int ap_matrix_mdev_get_device_info(unsigned long arg)
+{
+	unsigned long minsz;
+	struct vfio_device_info info;
+
+	minsz = offsetofend(struct vfio_device_info, num_irqs);
+
+	if (copy_from_user(&info, (void __user *)arg, minsz))
+		return -EFAULT;
+
+	if (info.argsz < minsz) {
+		pr_err("%s: Argument size %u less than min size %li",
+		       VFIO_AP_MATRIX_MODULE_NAME, info.argsz, minsz);
+		return -EINVAL;
+	}
+
+	info.flags = VFIO_DEVICE_FLAGS_AP_MATRIX;
+	info.num_regions = 0;
+	info.num_irqs = 0;
+
+	return copy_to_user((void __user *)arg, &info, minsz);
+}
+
+static ssize_t ap_matrix_mdev_ioctl(struct mdev_device *mdev,
+				    unsigned int cmd, unsigned long arg)
+{
+	int ret;
+
+	switch (cmd) {
+	case VFIO_DEVICE_GET_INFO:
+		ret = ap_matrix_mdev_get_device_info(arg);
+		break;
+	default:
+		pr_err("%s: ioctl command %d is not a supported command",
+		       VFIO_AP_MATRIX_MODULE_NAME, cmd);
+		ret = -EOPNOTSUPP;
+		break;
+	}
+
+	return ret;
+}
+
 static ssize_t name_show(struct kobject *kobj, struct device *dev, char *buf)
 {
 	return sprintf(buf, "%s\n", AP_MATRIX_MDEV_NAME_HWVIRT);
@@ -651,6 +693,7 @@ static DEVICE_ATTR(control_domains, 0644, ap_matrix_control_domains_show,
 	.remove                 = ap_matrix_mdev_remove,
 	.open                   = ap_matrix_mdev_open,
 	.release                = ap_matrix_mdev_release,
+	.ioctl                  = ap_matrix_mdev_ioctl,
 
 };
 
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 743456f..08f1ab4 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -199,6 +199,7 @@ struct vfio_device_info {
 #define VFIO_DEVICE_FLAGS_PLATFORM (1 << 2)	/* vfio-platform device */
 #define VFIO_DEVICE_FLAGS_AMBA  (1 << 3)	/* vfio-amba device */
 #define VFIO_DEVICE_FLAGS_CCW	(1 << 4)	/* vfio-ccw device */
+#define VFIO_DEVICE_FLAGS_AP_MATRIX (1 << 5)	/* vfio-ap-matrix device */
 	__u32	num_regions;	/* Max region index + 1 */
 	__u32	num_irqs;	/* Max IRQ index + 1 */
 };
-- 
1.7.1