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), GFP_KERNEL);
36 	if (!pasid_bitmap)
37 		return -ENOMEM;
38 
39 	set_bit(0, pasid_bitmap); /* PASID 0 is reserved. */
40 
41 	return 0;
42 }
43 
44 void kfd_pasid_exit(void)
45 {
46 	kfree(pasid_bitmap);
47 }
48 
49 bool kfd_set_pasid_limit(unsigned int new_limit)
50 {
51 	if (new_limit < pasid_limit) {
52 		bool ok;
53 
54 		mutex_lock(&pasid_mutex);
55 
56 		/* ensure that no pasids >= new_limit are in-use */
57 		ok = (find_next_bit(pasid_bitmap, pasid_limit, new_limit) ==
58 								pasid_limit);
59 		if (ok)
60 			pasid_limit = new_limit;
61 
62 		mutex_unlock(&pasid_mutex);
63 
64 		return ok;
65 	}
66 
67 	return true;
68 }
69 
70 inline unsigned int kfd_get_pasid_limit(void)
71 {
72 	return pasid_limit;
73 }
74 
75 unsigned int kfd_pasid_alloc(void)
76 {
77 	unsigned int found;
78 
79 	mutex_lock(&pasid_mutex);
80 
81 	found = find_first_zero_bit(pasid_bitmap, pasid_limit);
82 	if (found == pasid_limit)
83 		found = 0;
84 	else
85 		set_bit(found, pasid_bitmap);
86 
87 	mutex_unlock(&pasid_mutex);
88 
89 	return found;
90 }
91 
92 void kfd_pasid_free(unsigned int pasid)
93 {
94 	BUG_ON(pasid == 0 || pasid >= pasid_limit);
95 	clear_bit(pasid, pasid_bitmap);
96 }
97