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 }
88