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
  12 #include "vfio_ccw_private.h"
  13
  14 static ssize_t vfio_ccw_async_region_read(struct vfio_ccw_private *private,
  15                                           char __user *buf, size_t count,
  16                                           loff_t *ppos)
  17 {
  18         unsigned int i = VFIO_CCW_OFFSET_TO_INDEX(*ppos) - VFIO_CCW_NUM_REGIONS;
  19         loff_t pos = *ppos & VFIO_CCW_OFFSET_MASK;
  20         struct ccw_cmd_region *region;
  21         int ret;
  22
  23         if (pos + count > sizeof(*region))
  24                 return -EINVAL;
  25
  26         mutex_lock(&private->io_mutex);
  27         region = private->region[i].data;
  28         if (copy_to_user(buf, (void *)region + pos, count))
  29                 ret = -EFAULT;
  30         else
  31                 ret = count;
  32         mutex_unlock(&private->io_mutex);
  33         return ret;
  34 }
  35
  36 static ssize_t vfio_ccw_async_region_write(struct vfio_ccw_private *private,
  37                                            const char __user *buf, size_t count,
  38                                            loff_t *ppos)
  39 {
  40         unsigned int i = VFIO_CCW_OFFSET_TO_INDEX(*ppos) - VFIO_CCW_NUM_REGIONS;
  41         loff_t pos = *ppos & VFIO_CCW_OFFSET_MASK;
  42         struct ccw_cmd_region *region;
  43         int ret;
  44
  45         if (pos + count > sizeof(*region))
  46                 return -EINVAL;
  47
  48         if (!mutex_trylock(&private->io_mutex))
  49                 return -EAGAIN;
  50
  51         region = private->region[i].data;
  52         if (copy_from_user((void *)region + pos, buf, count)) {
  53                 ret = -EFAULT;
  54                 goto out_unlock;
  55         }
  56
  57         vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_ASYNC_REQ);
  58
  59         ret = region->ret_code ? region->ret_code : count;
  60
  61 out_unlock:
  62         mutex_unlock(&private->io_mutex);
  63         return ret;
  64 }
  65
  66 static void vfio_ccw_async_region_release(struct vfio_ccw_private *private,
  67                                           struct vfio_ccw_region *region)
  68 {
  69
  70 }
  71
  72 static const struct vfio_ccw_regops vfio_ccw_async_region_ops = {
  73         .read = vfio_ccw_async_region_read,
  74         .write = vfio_ccw_async_region_write,
  75         .release = vfio_ccw_async_region_release,
  76 };
  77
  78 int vfio_ccw_register_async_dev_regions(struct vfio_ccw_private *private)
  79 {
  80         return vfio_ccw_register_dev_region(private,
  81                                             VFIO_REGION_SUBTYPE_CCW_ASYNC_CMD,
  82                                             &vfio_ccw_async_region_ops,
  83                                             sizeof(struct ccw_cmd_region),
  84                                             VFIO_REGION_INFO_FLAG_READ |
  85                                             VFIO_REGION_INFO_FLAG_WRITE,
  86                                             private->cmd_region);
  87 }