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

[Dong Jia Shi]

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 <address@hidden>
Signed-off-by: Dong Jia Shi <address@hidden>
---
 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 <address@hidden>
+ */
+
+#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