1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_VIRTIO_FEATURES_H
3 #define _LINUX_VIRTIO_FEATURES_H
4
5 #include <linux/bits.h>
6 #include <linux/bug.h>
7 #include <linux/string.h>
8
9 #define VIRTIO_FEATURES_U64S 2
10 #define VIRTIO_FEATURES_BITS (VIRTIO_FEATURES_U64S * 64)
11
12 #define VIRTIO_BIT(b) BIT_ULL((b) & 0x3f)
13 #define VIRTIO_U64(b) ((b) >> 6)
14
15 #define VIRTIO_DECLARE_FEATURES(name) \
16 union { \
17 u64 name; \
18 u64 name##_array[VIRTIO_FEATURES_U64S];\
19 }
20
virtio_features_chk_bit(unsigned int bit)21 static inline bool virtio_features_chk_bit(unsigned int bit)
22 {
23 if (__builtin_constant_p(bit)) {
24 /*
25 * Don't care returning the correct value: the build
26 * will fail before any bad features access
27 */
28 BUILD_BUG_ON(bit >= VIRTIO_FEATURES_BITS);
29 } else {
30 if (WARN_ON_ONCE(bit >= VIRTIO_FEATURES_BITS))
31 return false;
32 }
33 return true;
34 }
35
virtio_features_test_bit(const u64 * features,unsigned int bit)36 static inline bool virtio_features_test_bit(const u64 *features,
37 unsigned int bit)
38 {
39 return virtio_features_chk_bit(bit) &&
40 !!(features[VIRTIO_U64(bit)] & VIRTIO_BIT(bit));
41 }
42
virtio_features_set_bit(u64 * features,unsigned int bit)43 static inline void virtio_features_set_bit(u64 *features,
44 unsigned int bit)
45 {
46 if (virtio_features_chk_bit(bit))
47 features[VIRTIO_U64(bit)] |= VIRTIO_BIT(bit);
48 }
49
virtio_features_clear_bit(u64 * features,unsigned int bit)50 static inline void virtio_features_clear_bit(u64 *features,
51 unsigned int bit)
52 {
53 if (virtio_features_chk_bit(bit))
54 features[VIRTIO_U64(bit)] &= ~VIRTIO_BIT(bit);
55 }
56
virtio_features_zero(u64 * features)57 static inline void virtio_features_zero(u64 *features)
58 {
59 memset(features, 0, sizeof(features[0]) * VIRTIO_FEATURES_U64S);
60 }
61
virtio_features_from_u64(u64 * features,u64 from)62 static inline void virtio_features_from_u64(u64 *features, u64 from)
63 {
64 virtio_features_zero(features);
65 features[0] = from;
66 }
67
virtio_features_equal(const u64 * f1,const u64 * f2)68 static inline bool virtio_features_equal(const u64 *f1, const u64 *f2)
69 {
70 int i;
71
72 for (i = 0; i < VIRTIO_FEATURES_U64S; ++i)
73 if (f1[i] != f2[i])
74 return false;
75 return true;
76 }
77
virtio_features_copy(u64 * to,const u64 * from)78 static inline void virtio_features_copy(u64 *to, const u64 *from)
79 {
80 memcpy(to, from, sizeof(to[0]) * VIRTIO_FEATURES_U64S);
81 }
82
virtio_features_andnot(u64 * to,const u64 * f1,const u64 * f2)83 static inline void virtio_features_andnot(u64 *to, const u64 *f1, const u64 *f2)
84 {
85 int i;
86
87 for (i = 0; i < VIRTIO_FEATURES_U64S; i++)
88 to[i] = f1[i] & ~f2[i];
89 }
90
91 #endif
92