1 files changed, 88 insertions, 0 deletions
diff --git a/include/linux/virtio_features.h b/include/linux/virtio_features.h
new file mode 100644
index 000000000000..f748f2f87de8
--- /dev/null
+++ b/include/linux/virtio_features.h
@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_VIRTIO_FEATURES_H
+#define _LINUX_VIRTIO_FEATURES_H
+
+#include <linux/bits.h>
+
+#define VIRTIO_FEATURES_DWORDS	2
+#define VIRTIO_FEATURES_MAX	(VIRTIO_FEATURES_DWORDS * 64)
+#define VIRTIO_FEATURES_WORDS	(VIRTIO_FEATURES_DWORDS * 2)
+#define VIRTIO_BIT(b)		BIT_ULL((b) & 0x3f)
+#define VIRTIO_DWORD(b)		((b) >> 6)
+#define VIRTIO_DECLARE_FEATURES(name)			\
+	union {						\
+		u64 name;				\
+		u64 name##_array[VIRTIO_FEATURES_DWORDS];\
+	}
+
+static inline bool virtio_features_chk_bit(unsigned int bit)
+{
+	if (__builtin_constant_p(bit)) {
+		/*
+		 * Don't care returning the correct value: the build
+		 * will fail before any bad features access
+		 */
+		BUILD_BUG_ON(bit >= VIRTIO_FEATURES_MAX);
+	} else {
+		if (WARN_ON_ONCE(bit >= VIRTIO_FEATURES_MAX))
+			return false;
+	}
+	return true;
+}
+
+static inline bool virtio_features_test_bit(const u64 *features,
+					    unsigned int bit)
+{
+	return virtio_features_chk_bit(bit) &&
+	       !!(features[VIRTIO_DWORD(bit)] & VIRTIO_BIT(bit));
+}
+
+static inline void virtio_features_set_bit(u64 *features,
+					   unsigned int bit)
+{
+	if (virtio_features_chk_bit(bit))
+		features[VIRTIO_DWORD(bit)] |= VIRTIO_BIT(bit);
+}
+
+static inline void virtio_features_clear_bit(u64 *features,
+					     unsigned int bit)
+{
+	if (virtio_features_chk_bit(bit))
+		features[VIRTIO_DWORD(bit)] &= ~VIRTIO_BIT(bit);
+}
+
+static inline void virtio_features_zero(u64 *features)
+{
+	memset(features, 0, sizeof(features[0]) * VIRTIO_FEATURES_DWORDS);
+}
+
+static inline void virtio_features_from_u64(u64 *features, u64 from)
+{
+	virtio_features_zero(features);
+	features[0] = from;
+}
+
+static inline bool virtio_features_equal(const u64 *f1, const u64 *f2)
+{
+	int i;
+
+	for (i = 0; i < VIRTIO_FEATURES_DWORDS; ++i)
+		if (f1[i] != f2[i])
+			return false;
+	return true;
+}
+
+static inline void virtio_features_copy(u64 *to, const u64 *from)
+{
+	memcpy(to, from, sizeof(to[0]) * VIRTIO_FEATURES_DWORDS);
+}
+
+static inline void virtio_features_andnot(u64 *to, const u64 *f1, const u64 *f2)
+{
+	int i;
+
+	for (i = 0; i < VIRTIO_FEATURES_DWORDS; i++)
+		to[i] = f1[i] & ~f2[i];
+}
+
+#endif