drivers/s390/cio/vfio_ccw_async.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Async I/O region for vfio_ccw
   4  *
   5  * Copyright Red Hat, Inc. 2019
   6  *
   7  * Author(s): Cornelia Huck <cohuck@redhat.com>
   8  */
   9
  10 #include <linux/vfio.h>
  11 #include <linux/mdev.h>
  12
  13 #include "vfio_ccw_private.h"
  14
  15 static ssize_t vfio_ccw_async_region_read(struct vfio_ccw_private *private,
  16                                           char __user *buf, size_t count,
  17                                           loff_t *ppos)
  18 {
  19         unsigned int i = VFIO_CCW_OFFSET_TO_INDEX(*ppos) - VFIO_CCW_NUM_REGIONS;
  20         loff_t pos = *ppos & VFIO_CCW_OFFSET_MASK;
  21         struct ccw_cmd_region *region;
  22         int ret;
  23
  24         if (pos + count > sizeof(*region))
  25                 return -EINVAL;
  26
  27         mutex_lock(&private->io_mutex);
  28         region = private->region[i].data;
  29         if (copy_to_user(buf, (void *)region + pos, count))
  30                 ret = -EFAULT;
  31         else
  32                 ret = count;
  33         mutex_unlock(&private->io_mutex);
  34         return ret;
  35 }
  36
  37 static ssize_t vfio_ccw_async_region_write(struct vfio_ccw_private *private,
  38                                            const char __user *buf, size_t count,
  39                                            loff_t *ppos)
  40 {
  41         unsigned int i = VFIO_CCW_OFFSET_TO_INDEX(*ppos) - VFIO_CCW_NUM_REGIONS;
  42         loff_t pos = *ppos & VFIO_CCW_OFFSET_MASK;
  43         struct ccw_cmd_region *region;
  44         int ret;
  45
  46         if (pos + count > sizeof(*region))
  47                 return -EINVAL;
  48
  49         if (!mutex_trylock(&private->io_mutex))
  50                 return -EAGAIN;
  51
  52         region = private->region[i].data;
  53         if (copy_from_user((void *)region + pos, buf, count)) {
  54                 ret = -EFAULT;
  55                 goto out_unlock;
  56         }
  57
  58         vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_ASYNC_REQ);
  59
  60         ret = region->ret_code ? region->ret_code : count;
  61
  62 out_unlock:
  63         mutex_unlock(&private->io_mutex);
  64         return ret;
  65 }
  66
  67 static void vfio_ccw_async_region_release(struct vfio_ccw_private *private,
  68                                           struct vfio_ccw_region *region)
  69 {
  70
  71 }
  72
  73 static const struct vfio_ccw_regops vfio_ccw_async_region_ops = {
  74         .read = vfio_ccw_async_region_read,
  75         .write = vfio_ccw_async_region_write,
  76         .release = vfio_ccw_async_region_release,
  77 };
  78
  79 int vfio_ccw_register_async_dev_regions(struct vfio_ccw_private *private)
  80 {
  81         return vfio_ccw_register_dev_region(private,
  82                                             VFIO_REGION_SUBTYPE_CCW_ASYNC_CMD,
  83                                             &vfio_ccw_async_region_ops,
  84                                             sizeof(struct ccw_cmd_region),
  85                                             VFIO_REGION_INFO_FLAG_READ |
  86                                             VFIO_REGION_INFO_FLAG_WRITE,
  87                                             private->cmd_region);
  88 }