1 /*
2  * Copyright 2014 Advanced Micro Devices, Inc.
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a
5  * copy of this software and associated documentation files (the "Software"),
6  * to deal in the Software without restriction, including without limitation
7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8  * and/or sell copies of the Software, and to permit persons to whom the
9  * Software is furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice shall be included in
12  * all copies or substantial portions of the Software.
13  *
14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
17  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
18  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
19  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
20  * OTHER DEALINGS IN THE SOFTWARE.
21  */
22 
23 #include <linux/slab.h>
24 #include <linux/types.h>
25 #include "kfd_priv.h"
26 
27 static unsigned long *pasid_bitmap;
28 static unsigned int pasid_limit;
29 static DEFINE_MUTEX(pasid_mutex);
30 
31 int kfd_pasid_init(void)
32 {
33 	pasid_limit = KFD_MAX_NUM_OF_PROCESSES;
34 
35 	pasid_bitmap = kcalloc(BITS_TO_LONGS(pasid_limit), sizeof(long),
36 				GFP_KERNEL);
37 	if (!pasid_bitmap)
38 		return -ENOMEM;
39 
40 	set_bit(0, pasid_bitmap); /* PASID 0 is reserved. */
41 
42 	return 0;
43 }
44 
45 void kfd_pasid_exit(void)
46 {
47 	kfree(pasid_bitmap);
48 }
49 
50 bool kfd_set_pasid_limit(unsigned int new_limit)
51 {
52 	if (new_limit < pasid_limit) {
53 		bool ok;
54 
55 		mutex_lock(&pasid_mutex);
56 
57 		/* ensure that no pasids >= new_limit are in-use */
58 		ok = (find_next_bit(pasid_bitmap, pasid_limit, new_limit) ==
59 								pasid_limit);
60 		if (ok)
61 			pasid_limit = new_limit;
62 
63 		mutex_unlock(&pasid_mutex);
64 
65 		return ok;
66 	}
67 
68 	return true;
69 }
70 
71 inline unsigned int kfd_get_pasid_limit(void)
72 {
73 	return pasid_limit;
74 }
75 
76 unsigned int kfd_pasid_alloc(void)
77 {
78 	unsigned int found;
79 
80 	mutex_lock(&pasid_mutex);
81 
82 	found = find_first_zero_bit(pasid_bitmap, pasid_limit);
83 	if (found == pasid_limit)
84 		found = 0;
85 	else
86 		set_bit(found, pasid_bitmap);
87 
88 	mutex_unlock(&pasid_mutex);
89 
90 	return found;
91 }
92 
93 void kfd_pasid_free(unsigned int pasid)
94 {
95 	if (!WARN_ON(pasid == 0 || pasid >= pasid_limit))
96 		clear_bit(pasid, pasid_bitmap);
97 }
98