[PATCH v4 07/16] vfio: ccw: introduce ccw_io_region

Dong Jia Shi
2017-03-17T03:17:34Z

To provide user-space a set of interfaces to:
1. pass in a ccw program to perform an I/O operation.
2. read back I/O results of the completed I/O operations.
We introduce an MMIO region for the vfio-ccw device here.

This region is defined to content:
1. areas to store arguments that an ssch required.
2. areas to store the I/O results.

Using pwrite/pread to the device on this region, a user-space program
could write/read data to/from the vfio-ccw device.

Reviewed-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
---
drivers/s390/cio/vfio_ccw_ops.c | 47 +++++++++++++++++++++++++++++++++++++
drivers/s390/cio/vfio_ccw_private.h | 4 ++++
include/uapi/linux/vfio_ccw.h | 24 +++++++++++++++++++
3 files changed, 75 insertions(+)
create mode 100644 include/uapi/linux/vfio_ccw.h

diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index b8a2fed..6c06805 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -127,6 +127,51 @@ void vfio_ccw_mdev_release(struct mdev_device *mdev)
&private->nb);
}

+static ssize_t vfio_ccw_mdev_read(struct mdev_device *mdev,
+ char __user *buf,
+ size_t count,
+ loff_t *ppos)
+{
+ struct vfio_ccw_private *private;
+ struct ccw_io_region *region;
+
+ if (*ppos + count > sizeof(*region))
+ return -EINVAL;
+
+ private = dev_get_drvdata(mdev_parent_dev(mdev));
+ if (!private)
+ return -ENODEV;
+
+ region = &private->io_region;
+ if (copy_to_user(buf, (void *)region + *ppos, count))
+ return -EFAULT;
+
+ return count;
+}
+
+static ssize_t vfio_ccw_mdev_write(struct mdev_device *mdev,
+ const char __user *buf,
+ size_t count,
+ loff_t *ppos)
+{
+ struct vfio_ccw_private *private;
+ struct ccw_io_region *region;
+
+ if (*ppos + count > sizeof(*region))
+ return -EINVAL;
+
+ private = dev_get_drvdata(mdev_parent_dev(mdev));
+ if (!private)
+ return -ENODEV;
+
+ region = &private->io_region;
+ if (copy_from_user((void *)region + *ppos, buf, count))
+ return -EFAULT;
+ region->ret_code = 0;
+
+ return count;
+}
+
static const struct mdev_parent_ops vfio_ccw_mdev_ops = {
.owner = THIS_MODULE,
.supported_type_groups = mdev_type_groups,
@@ -134,6 +179,8 @@ static const struct mdev_parent_ops vfio_ccw_mdev_ops = {
.remove = vfio_ccw_mdev_remove,
.open = vfio_ccw_mdev_open,
.release = vfio_ccw_mdev_release,
+ .read = vfio_ccw_mdev_read,
+ .write = vfio_ccw_mdev_write,
};

int vfio_ccw_mdev_reg(struct subchannel *sch)
diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h
index 5afb3ba..359e96b 100644
--- a/drivers/s390/cio/vfio_ccw_private.h
+++ b/drivers/s390/cio/vfio_ccw_private.h
@@ -10,6 +10,8 @@
#ifndef _VFIO_CCW_PRIVATE_H_
#define _VFIO_CCW_PRIVATE_H_

+#include <linux/vfio_ccw.h>
+
#include "css.h"

/**
@@ -19,6 +21,7 @@
* @avail: available for creating a mediated device
* @mdev: pointer to the mediated device
* @nb: notifier for vfio events
+ * @io_region: MMIO region to input/output I/O arguments/results
*/
struct vfio_ccw_private {
struct subchannel *sch;
@@ -26,6 +29,7 @@ struct vfio_ccw_private {
atomic_t avail;
struct mdev_device *mdev;
struct notifier_block nb;
+ struct ccw_io_region io_region;
} __aligned(8);

extern int vfio_ccw_mdev_reg(struct subchannel *sch);
diff --git a/include/uapi/linux/vfio_ccw.h b/include/uapi/linux/vfio_ccw.h
new file mode 100644
index 0000000..34a7f6f
--- /dev/null
+++ b/include/uapi/linux/vfio_ccw.h
@@ -0,0 +1,24 @@
+/*
+ * Interfaces for vfio-ccw
+ *
+ * Copyright IBM Corp. 2017
+ *
+ * Author(s): Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
+ */
+
+#ifndef _VFIO_CCW_H_
+#define _VFIO_CCW_H_
+
+#include <linux/types.h>
+
+struct ccw_io_region {
+#define ORB_AREA_SIZE 12
+ __u8 orb_area[ORB_AREA_SIZE];
+#define SCSW_AREA_SIZE 12
+ __u8 scsw_area[SCSW_AREA_SIZE];
+#define IRB_AREA_SIZE 96
+ __u8 irb_area[IRB_AREA_SIZE];
+ __u32 ret_code;
+} __packed;
+
+#endif
--
2.8.4