Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1#ifndef _LINUX_VIRTIO_RING_H
2#define _LINUX_VIRTIO_RING_H
3
4#include <asm/barrier.h>
5#include <linux/irqreturn.h>
6#include <uapi/linux/virtio_ring.h>
7
8/*
9 * Barriers in virtio are tricky. Non-SMP virtio guests can't assume
10 * they're not on an SMP host system, so they need to assume real
11 * barriers. Non-SMP virtio hosts could skip the barriers, but does
12 * anyone care?
13 *
14 * For virtio_pci on SMP, we don't need to order with respect to MMIO
15 * accesses through relaxed memory I/O windows, so virt_mb() et al are
16 * sufficient.
17 *
18 * For using virtio to talk to real devices (eg. other heterogeneous
19 * CPUs) we do need real barriers. In theory, we could be using both
20 * kinds of virtio, so it's a runtime decision, and the branch is
21 * actually quite cheap.
22 */
23
24static inline void virtio_mb(bool weak_barriers)
25{
26 if (weak_barriers)
27 virt_mb();
28 else
29 mb();
30}
31
32static inline void virtio_rmb(bool weak_barriers)
33{
34 if (weak_barriers)
35 virt_rmb();
36 else
37 rmb();
38}
39
40static inline void virtio_wmb(bool weak_barriers)
41{
42 if (weak_barriers)
43 virt_wmb();
44 else
45 wmb();
46}
47
48static inline void virtio_store_mb(bool weak_barriers,
49 __virtio16 *p, __virtio16 v)
50{
51 if (weak_barriers) {
52 virt_store_mb(*p, v);
53 } else {
54 WRITE_ONCE(*p, v);
55 mb();
56 }
57}
58
59struct virtio_device;
60struct virtqueue;
61
62struct virtqueue *vring_new_virtqueue(unsigned int index,
63 unsigned int num,
64 unsigned int vring_align,
65 struct virtio_device *vdev,
66 bool weak_barriers,
67 void *pages,
68 bool (*notify)(struct virtqueue *vq),
69 void (*callback)(struct virtqueue *vq),
70 const char *name);
71void vring_del_virtqueue(struct virtqueue *vq);
72/* Filter out transport-specific feature bits. */
73void vring_transport_features(struct virtio_device *vdev);
74
75irqreturn_t vring_interrupt(int irq, void *_vq);
76#endif /* _LINUX_VIRTIO_RING_H */