virtio_features.h

 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
21static 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
36static 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
43static 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
50static 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
57static inline void virtio_features_zero(u64 *features)
58{
59	memset(features, 0, sizeof(features[0]) * VIRTIO_FEATURES_U64S);
60}
61
62static inline void virtio_features_from_u64(u64 *features, u64 from)
63{
64	virtio_features_zero(features);
65	features[0] = from;
66}
67
68static 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
78static inline void virtio_features_copy(u64 *to, const u64 *from)
79{
80	memcpy(to, from, sizeof(to[0]) * VIRTIO_FEATURES_U64S);
81}
82
83static 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